Establishing the diagnosis of Cushing's syndrome

Transcription

1 Page 1 of 16 Official reprint from UpToDate Print Back Establishing the diagnosis of Cushing's syndrome Author Lynnette K Nieman, MD Section Editor Andre Lacroix, MD Deputy Editor Kathryn A Martin, MD Last literature review for version 17.1: January 1, 2009 This topic last updated: November 26, 2008 INTRODUCTION The possible presence of Cushing's syndrome is suggested by certain symptoms and signs. Unfortunately, none of these are pathognomonic, and many are nonspecific (eg, obesity, hypertension, menstrual irregularity, and glucose intolerance). As a result, the diagnosis must be confirmed by biochemical tests. The laboratory diagnostic evaluation to determine if the patient has hypercortisolism (Cushing's syndrome), will be reviewed here. The approach to the differential diagnosis of established hypercortisolism is discussed separately. (See "Establishing the cause of Cushing's syndrome"). EXCLUDE EXOGENOUS GLUCOCORTICOIDS Before evaluation for possible Cushing's syndrome, it is essential that a careful history has excluded exogenous glucocorticoid intake. Ingestion of glucocorticoids may take two forms: The most common cause of hypercortisolism is ingestion of prescribed prednisone, usually for nonendocrine disease. However, Cushing's syndrome also can be caused by other oral, injected, topical, and inhaled glucocorticoids [1-3], and by medroxyprogesterone acetate, a progestin with some intrinsic glucocorticoid activity [4]. The clearance of some inhaled steroids may be delayed by ritonovir, leading to Cushing's syndrome [5]. Cushing's syndrome may also be caused by the use of glucocorticoid-containing creams or herbal preparations [6,7]. Factitious Cushing's syndrome is a rare disorder that refers to surreptitious intake of a glucocorticoid, often by patients who are close to the health professions [8,9]. All glucocorticoids, including potent inhaled and topical glucocorticoids such as beclomethasone and fluocinolone, inhibit ACTH secretion if given in sufficient doses. Thus, plasma ACTH and serum cortisol concentrations and urinary 17-hydroxycorticosteroid and cortisol excretion (unless cortisol or cortisone is the steroid administered) may all be low [9]. In contrast, urinary cortisol excretion may be falsely elevated with vulvovaginal application of hydrocortisone [10]. Factitious Cushing's syndrome is responsible for less than 1 percent of patients with Cushing's syndrome, but even a careful history may fail to detect this disorder and it may be difficult to exclude with laboratory tests [8,11,12]. Important clues to the diagnosis are low or erratic values for urinary cortisol, suggesting ingestion of a synthetic glucocorticoid or intermittent ingestion of cortisol or cortisone [8], or excessive urinary cortisol values relative to serum cortisol concentrations, suggesting the addition of hydrocortisone to urine specimens [12]. The most

2 Page 2 of 16 valuable laboratory test is the detection of synthetic glucocorticoids in the urine by high-pressure liquid chromatography [8,9,11]. PSEUDO-CUSHING'S SYNDROME Further complicating the diagnosis is the fact that hypercortisolism can occur in several disorders other than Cushing's syndrome. Examples include: Patients who are physically stressed, such as by a severe bacterial infection. Patients with severe obesity, especially those with visceral obesity or polycystic ovary syndrome. Patients with psychological stress, especially patients with a severe major depressive disorder and melancholic symptoms. Rarely, patients with chronic alcoholism. When such patients present with clinical features consistent with Cushing's syndrome, they are referred to as having pseudo-cushing's syndrome. However, the distinction is not always simple because patients with Cushing's syndrome can have serious infections, are frequently depressed (although it is often an atypical, agitated depression) [13,14], and presumably have a prevalence of chronic alcoholism similar to that of the general population. The psychiatric literature suggests that as many as 80 percent of patients with major depressive disorders have increased cortisol secretion [15-17]. However, cortisol hypersecretion, when present, is usually minimal. Furthermore, even severely depressed patients with substantial cortisol hypersecretion rarely develop clinical Cushing's syndrome. However, some depressed patients may be difficult to distinguish clinically or biochemically from those with Cushing's disease. Their abnormal cortisol secretion presumably results from hypothalamic-pituitary-adrenal axis hyperactivity [16] and disappears after remission of depression [18]. Chronic alcoholism is an even more uncommon cause of pseudo-cushing's syndrome [19], about three dozen patients with clinical or biochemical manifestations of Cushing's syndrome having been reported [20]. Most had liver dysfunction, although the hormonal changes did not correlate closely with the degree of abnormality in liver function. In addition to liver dysfunction, these patients probably have transiently increased secretion of corticotropin-releasing hormone (CRH) or impaired hypothalamic or pituitary responsiveness to cortisol. However, their peripheral and petrosal sinus plasma CRH concentrations are normal [21]. The hormonal abnormalities disappear rapidly during abstinence from alcohol. Clinically, patients with pseudo-cushing's syndrome seldom have the cutaneous (ie, easy bruising, thinning, and friability) or muscle (ie, proximal muscle atrophy and weakness) signs of Cushing's syndrome [22]. ADRENAL INCIDENTALOMAS AND SUBCLINICAL CUSHING'S Subclinical Cushing's syndrome, mild hypercortisolism without clinical manifestations of Cushing's syndrome, is the most frequent hormonal abnormality detected in patients with adrenal incidentalomas. Some adrenal incidentalomas secrete sufficient cortisol to suppress ACTH, at least partially. Although these patients lack many of the usual stigmata of overt Cushing's syndrome, they may have one or more of the effects of endogenous cortisol over-secretion such as obesity, hypertension,

3 Page 3 of 16 glucose intolerance or diabetes, dyslipdemia, osteoporosis. Depending on the importance of cortisol secretion by primary adrenal tumors, the spectrum of biochemical abnormalities will vary: milder cases will present normal 24-hour urinary cortisol levels with slightly elevated midnight salivary cortisol, incompletely suppressed morning serum cortisol following 1-mg dexamethasone suppression test (DST) and partially suppressed plasma ACTH levels, while in more severe cases, urinary free cortisol, midnight salivary cortisol, and serum cortisol following 1 mg DST will be clearly elevated and plasma ACTH may be undetectable. This topic is reviewed in detail separately (See "The adrenal incidentaloma"). DOES THE PATIENTS HAVE CUSHING'S SYNDROME? The initial diagnostic tests for hypercortisolism should be highly sensitive, even though the diagnosis may be excluded later by more specific tests [22,23]. We agree with the approach outlined by the evidence-based 2008 Endocrine Society Clinical Guidelines [24]: We recommend that at least two first-line tests should be abnormal to establish the diagnosis of Cushing's syndrome [24]. We suggest late night salivary cortisol, urinary cortisol, and the low-dose dexamethasone suppression tests as first line tests. We suggest using conservative criteria to interpret the tests to maximize sensitivity. Urinary and salivary cortisol measurements should be obtained at least twice. The urinary cortisol excretion should be unequivocally increased (threefold above the upper limit of normal for the assay), or the diagnosis of Cushing's syndrome is uncertain and other tests should be performed. The diagnosis of Cushing's syndrome is confirmed when two tests are unequivocally abnormal. The patient should undergo additional evaluation if the test results are discordant or only slightly abnormal. If test results are normal, the patient does not have Cushing's syndrome unless it is extremely mild or cyclic. We do not suggest additional evaluation unless symptoms progress or cyclic Cushing's syndrome is suspected. Diagnostic tests Daily urinary cortisol excretion Twenty-four-hour urinary cortisol excretion provides a direct and reliable practical index of cortisol secretion [25,26]. (See "Measurement of urinary excretion of endogenous and exogenous glucocorticoids"). ACTH and cortisol are secreted in discrete bursts, not only in normal subjects but also in most patients with Cushing's disease [27-29]; in addition, cortisol is secreted episodically by some adrenal tumors (show figure 1) [28]. Twenty-four hour urinary cortisol excretion is an integrated measure of the serum free cortisol concentration (ie, cortisol that is not bound to cortisol-binding globulin [CBG, transcortin] or other serum proteins). The two most important factors in obtaining a valid result are collection of a complete 24-hour specimen and a reliable reference laboratory. The former can usually be obtained by carefully explaining to the patient how to collect the specimen (see "Patient

4 Page 4 of 16 information: Collection of a 24-hour urine specimen") and by measuring urinary creatinine excretion. In adults under the age of 50 years, daily creatinine excretion should be 20 to 25 mg/kg (177 to 221 µmol/kg) lean body weight in men and 15 to 20 mg/kg (133 to 177 µmol/kg) lean body weight in women. From the ages of 50 to 90, there is a progressive 50 percent decline in creatinine excretion (to about 10 mg/kg in men), due primarily to a decline in muscle mass. Urinary cortisol may be detected by antibody-based techniques (immunoassays) or by structurally-based techniques (eg, high performance liquid chromatography, mass spectrometry, and combinations thereof). The former assays may be less specific since antibodies may crossreact with steroids that are similar to cortisol, but can be distinguished by the structurally based techniques. As a result, the normal range is often higher in the immunoassays. (See "Measurement of urinary excretion of endogenous and exogenous glucocorticoids").with respect to laboratory accuracy, some reference laboratories cannot measure urinary cortisol reliably. As a result, it is sometimes more efficient to rely upon a reputable specialized endocrine laboratory for measuring not only urinary cortisol, but also serum cortisol and plasma ACTH. A number of studies have evaluated the utility of urine cortisol as a screening test, using the upper limit of the normal range for different assays as the test criterion: A systematic review and meta-analysis of studies of diagnostic tests for Cushing's syndrome was performed in conjunction with the 2008 Endocrine Society Guidelines [30]. In their pooled analysis, tests with a high likelihood ratio for a positive (abnormal) test indicated tests that help rule in Cushing's syndrome, while those with a very low likelihood ratio for a negative (normal) test indicated tests that help rule it out. For urinary cortisol, they identified 14 studies including 646 patients with Cushing's syndrome and 5226 patients who did not have Cushing's syndrome. It reported a likelihood ratio of 10.6 (95% CI ) for an abnormal result and a likelihood ratio for Cushing's syndrome of 0.16 (95% CI ) for a normal result [30]. However, in another study of 58 patients evaluated prospectively because of mildly abnormal cortisol excretion or response to dexamethasone, 19 had pseudo-cushing's syndrome, suggesting that the false positive rate may be high in patients evaluated because of clinical suspicion of Cushing's syndrome [31]. In this study, all patients with pseudo-cushing's syndrome had urine cortisol excretion equal to or less than three times the upper limit of the normal range. In a study of 105 children with Cushing's syndrome, urine cortisol had a sensitivity of 88 percent (95% CI: 79%-93%) [32]. It may be easier for the patient to collect an overnight urine sample from 10 PM to 8 AM, rather than a 24-hour sample, as the initial test. When cortisol excretion is expressed as a function of urinary creatinine excretion, this test appears to give results as reliable as the 24-hour collection. In one series, 30 patients with Cushing's syndrome (21 Cushing's disease, 7 adrenal adenoma, 2 ectopic ACTH syndrome) excreted 44 to 5200 µg cortisol/g creatinine (14 to 1639 nmol cortisol/mmol creatinine) as compared with 4 to 68 µg cortisol/g creatinine (1.5 to 21.2 nmol cortisol/mmol creatinine) in 150 obese control subjects [33]. This promising test requires additional confirmation.

5 Page 5 of 16 The patient can be assumed to have Cushing's syndrome if basal urinary cortisol excretion is more than three times the upper limit of normal (which may vary somewhat in different assays) and one other test is abnormal. The patient should then be evaluated for the cause of the hypercortisolism. (See "Establishing the cause of Cushing's syndrome"). On the other hand, patients with equivocally raised values (above normal but less than three times the upper reference value) may have pseudo-cushing's syndrome and should either be reevaluated after several weeks or be subjected to one or more of the tests described next, depending upon the level of clinical suspicion. In a study of 426 patients with Cushing's syndrome, for example, 47 percent of 288 patients with Cushing's disease, 31 percent of 80 patients with adrenal adenoma, 21 percent of 25 patients with ectopic ACTH or CRH secretion, and 5 percent of 24 patients with adrenal carcinoma had at least one 24-hour urinary cortisol value in this equivocal range [34]. Up to 40 percent of patients with severe depression or polycystic ovary syndrome may have slightly high 24-hour urinary cortisol excretion [8,35]. People who drink very large volumes of liquid also excrete more cortisol (64 percent more cortisol excreted with an intake of five liters per day), while excretion of creatinine and 17-hydroxycorticosteroids remains unaltered [36]. Modest increases of urinary cortisol excretion in patients with urine volumes of more than three liters should be interpreted with caution. When choosing amongst the diagnostic tests, it may be argued that urine cortisol determinations are unnecessary, because late evening serum or salivary cortisol values have similar diagnostic utility and are more convenient. If it is not convenient to collect urine as a second test, then the dexamethasone suppression test should be used in combination with a late night cortisol test. UFC may not be the ideal test in patients with mild Cushing's syndrome caused by an adrenal incidentaloma, who may have normal urine cortisol values but an elevated evening cortisol concentration [24]. Conversely, if urinary cortisol excretion is indeterminate and the late evening serum cortisol concentrations are normal, the patient does not have Cushing's syndrome unless it is cyclic or mild [37,38]. These examples illustrate the need for complementary tests, and careful consideration of the tests that are chosen. Low-dose dexamethasone suppression tests Exogenous dexamethasone substitutes for endogenous cortisol in suppressing ACTH release. The dexamethasone dosages used should reliably suppress ACTH secretion by the normal pituitary gland, leading to suppression of cortisol secretion and subsequent reductions in serum cortisol concentrations and urinary excretion of cortisol and cortisol metabolites. There are two forms of the low-dose dexamethasone suppression test [13]. (See "Dexamethasone suppression tests" for a complete discussion of the different tests). The low-dose dexamethasone suppression tests are standard screening tests to differentiate patients with Cushing's syndrome of any cause from patients who do not have Cushing's syndrome. The high-dose dexamethasone suppression tests were used to distinguish patients with Cushing's disease (Cushing's syndrome caused by pituitary hypersecretion of corticotropin [ACTH]) from most patients with the ectopic ACTH syndrome (Cushing's syndrome caused by nonpituitary ACTH-secreting tumors). (See "Dexamethasone suppression tests" and see "Establishing the cause of Cushing's syndrome").

6 Page 6 of 16 The dexamethasone suppression tests are not a good choice for patients in whom CBG levels may be abnormal or in those taking medications that may alter the metabolism of the drug [39]. These patients may have either a falsely positive or negative result. Overnight 1 mg test The overnight test consists of administration of 1.0 mg of dexamethasone at 11 PM to 12 AM, and measurement of serum cortisol at 8 AM the next morning. Using current specific immunoassays, most normal individuals have an 8 AM serum cortisol value of less than 2 mcg/dl (55 nmol/l) [39]. (See "Measurement of cortisol in serum and saliva"). The 2008 Endocrine Society Guidelines suggest a diagnostic cortisol criterion of 1.8 mcg/dl (50 nmol/l), recognizing that this choice will optimize sensitivity but decrease specificity. Despite use of this stringent criterion for sensitivity, in one study 8 percent of patients with Cushing's disease showed suppression to less than 2 mcg/dl (55 nmol/l) [40]. The low-dose dexamethasone tests should not be used as the sole criterion for the diagnosis of Cushing's syndrome. At least one additional test should be done to establish or exclude the diagnosis. The 1 mg dexamethasone test is described in greater detail separately. (See "Dexamethasone suppression tests"). Standard two-day 2 mg test The two-day 2 mg test consists of administering 0.5 mg of dexamethasone every six hours for eight doses, and measurement of serum cortisol either two or six hours after the last dose. Because the sensitivity and specificity using urine corticosteroids are low, these endpoints are not recommended. The same criteria for normal suppression (< 1.8 mcg/dl (<50 nmol/l) used for the 1 mg dexamethasone test are used for the two-day 2 mg test. The 2-day 2 mg dexamethasone test is described in greater detail separately. (See "Dexamethasone suppression tests"). Diagnostic accuracy In the meta-analysis described above, the 1 mg dexamethasone test and the 2-day 2 mg test were both accurate diagnostic tests, but the 2 mg test had slightly less diagnostic accuracy [30]. (See "Daily urinary cortisol excretion" above): For the 1 mg test, 14 studies including 249 patients with Cushing's syndrome out of 5305 undergoing testing (using various diagnostic criteria), there was a likelihood ratio of 16.4 (CI ) for an abnormal result and 0.06 ( ) for a normal result. For the 2-day 2 mg test, 8 studies were identified, including 136 patients with Cushing's syndrome out of 323 who were tested. It found a likelihood ratio of 7.3 (CI ) for an abnormal result and 0.18 (CI ) for a normal result. Serum collected at the time of cortisol measurement should be retained for measurement of dexamethasone, to clarify otherwise confusing results caused by noncompliance and individual variability in, and drug effects on, dexamethasone metabolism [41,42]. The choice of commercial assays for dexamethasone should be based on the availability of a nomogram for expected results. It is possible that some patients with "normal" suppressibility to dexamethasone are slow metabolizers of the agent so that the effective dose is larger. This is inferred if the dexamethasone level is above the expected range. It should be possible to measure salivary dexamethasone in conjunction with salivary cortisol to validate suppression of cortisol secretion, but the normal

7 Page 7 of 16 range for salivary dexamethasone during these tests has not been determined. There are some patients in whom an unequivocal conclusion cannot be reached after measurement of two tests. Another first-line test may be useful in identifying patients in this group who have Cushing's syndrome. Late evening salivary cortisol Measurements of morning serum or salivary cortisol concentrations in patients suspected of having Cushing's syndrome have no diagnostic value unless they are extremely elevated. Measurement of serum or salivary cortisol in the late evening is based upon the fact that the normal evening nadir in serum cortisol is preserved in obese and depressed patients but not in those with Cushing's syndrome. (See "Measurement of cortisol in serum and saliva"). A late evening salivary cortisol concentration can be used to establish the diagnosis of Cushing's syndrome [43-50]. Saliva is easily collected and cortisol is stable in saliva even at room temperature for several days. Saliva collection has the distinct advantage of being noninvasive, and can be performed by the patient at home. It is especially useful for patients suspected of having cyclical or intermittent Cushing's syndrome, who can collect many samples over an extended period of time and return the accumulated samples to the physician at one time. As with other cortisol assays, it is useful to evaluate at least three samples from different days. The criteria used to interpret salivary cortisol results differ among studies, perhaps because of assay or collection differences. As a result, published reference ranges are not appropriate for all commercial assays [51] (show table 1). (See "Measurement of cortisol in serum and saliva"). In addition, a study of older men (mean age 61 years), some with co-morbidities of diabetes and/or hypertension, showed poor specificity. Twenty percent of the participants had a late night salivary cortisol value above the upper limit of normal (1.6 ng/ml, 4.3 nmol/l) when measured by enzyme immunoassay [52]. In the meta-analysis described above, midnight salivary cortisol was an accurate diagnostic test. A meta-analysis of six studies included 136 patients with Cushing's syndrome out of 323 tested [30]. It found a likelihood ratio of 9.5 (CI ) for an abnormal result and a likelihood ratio of 0.09 (CI ) for a normal result. (See "Daily urinary cortisol excretion" above). Thus, while a late evening salivary cortisol measurement is a useful test for the diagnosis of Cushing's syndrome, appropriate assay-specific and perhaps age-specific normative values must be used for its interpretation. In some situations, other second line tests may be used. These tests may be chosen because of site-specific constraints, lack of access to salivary cortisol assays, or preferences based on experience. Late evening serum cortisol Measurement of serum or salivary cortisol in the late evening is based upon the fact that the normal evening nadir in serum cortisol is preserved in obese and depressed patients but not in those with Cushing's syndrome. (See "Measurement of cortisol in serum and saliva").

8 Page 8 of 16 One study achieved 100 percent sensitivity and specificity in 20 normal individuals and 150 patients with Cushing's syndrome using an exclusion criterion of <2 mcg/dl (50 nmol/l) [53]. Three of the patients who had Cushing's disease had serum cortisol concentrations below 2 mcg/dl (50 nmol/l) after a two-day low-dose dexamethasone suppression test. In a subsequent study of 198 patients with Cushing's disease, 27 patients with the ectopic ACTH syndrome, 15 patients with primary adrenal Cushing's syndrome and 23 patients with pseudo-cushing's syndrome, a single midnight serum cortisol concentration >7.5 mcg/dl (207 nmol/l) correctly identified 225 of the patients with Cushing's syndrome and all 23 patients with pseudo-cushing's (96 percent sensitivity, 100 percent specificity) [54]. When the lower criterion (2 mcg/dl, or 50 nmol/l) was applied to these patients, it resulted in 99.6 percent sensitivity, but only 26 percent specificity, presumably because the earlier comparison group was normal subjects, rather than patients with pseudo-cushing's syndrome. Thus, the higher criterion is recommended [24]. One study of 105 children with Cushing's syndrome found that a single midnight cortisol level of 4.4 mcg/dl (121 nmol/l) gave a sensitivity of 99% (95% CI: 94%-100%) while no child without the condition had a higher value [32]. This test has usually been performed in the hospital, and one group obtains the blood after the patient appears to be asleep [53]. However, sleeping versus awake results have not been evaluated systematically, and our experience is that the test can reliably be performed on an ambulatory basis. This can be done by inserting a heparin-lock earlier in the day to avoid stressinduced cortisol released caused by the anticipation of or pain caused by venipuncture, and asking the patient tp return between 11 PM and midnight for blood drawing. We try to obtain samples on at least two evenings. Patients with intermediate values should be reevaluated after several weeks. (See "Measurement of cortisol in serum and saliva"). CRH after dexamethasone test The CRH after dexamethasone test exploits the greater sensitivity of ACTH secretion to dexamethasone suppression in depressed patients [55] and their blunted serum cortisol response to exogenous CRH as compared with patients with Cushing's syndrome [17]. However, neither of these responses alone provides a reliable method for distinguishing depressed patients from those with Cushing's syndrome [31]. In one report, for example, the serum cortisol concentration was <1.4 mcg/dl (38 nmol/l) 15 minutes after CRH (given two hours after the last 0.5 mg dexamethasone dose in the standard two-day low-dose dexamethasone test) in all 19 patients with pseudo-cushing's syndrome versus none of 35 patients with Cushing's disease, none of two with ectopic ACTH secretion, and none of two with primary adrenal disease (100 percent sensitivity and 100 percent specificity for Cushing's syndrome) [31]. However, only the 15-minute sample was accurate, and a serum cortisol concentration <1.4 mcg/dl (38 nmol/l) two hours after the last dexamethasone dose had 90 percent sensitivity and 100 percent specificity without the administration of CRH. This test needs further evaluation to confirm its efficacy. It can give false positive results in patients with anorexia nervosa and in endurance-trained men [56,57]; while it is unlikely that patients with anorexia

9 Page 9 of 16 nervosa would be screened for Cushing's syndrome, these results should be considered when testing patients who exercise vigorously. (See "Corticotropin-releasing hormone stimulation test"). Two smaller studies of about 40 patients being evaluated for Cushing's syndrome did not confirm the improved diagnostic accuracy of the CRH after dexamethasone test when compared to the low-dose dexamethasone test alone [58,59]. It is not clear whether these differences reflect differences in dexamethasone metabolism, as dexamethasone levels were not evaluated, or differences in the cortisol assays. In a third study, the test performed as well as repeated examination of routine tests in six patients with appropriate dexamethasone levels in whom the diagnosis was initially unclear [60]. Other tests Other tests have been developed for the diagnosis of Cushing's syndrome, but have not been widely adopted. The naloxone test is based upon the assumption that endogenous CRH secretion is suppressed in patients with Cushing's disease and that the opioid antagonist, naloxone (250 mcg/kg body weight intravenously), releases endogenous CRH [61]. Naloxone probably also releases some CRH in patients with Cushing's disease [62], but the increases in plasma ACTH and serum cortisol concentrations are less than those in depressed patients [63]. The insulin-induced hypoglycemia test utilizes the fact that the hypercortisolism of depression is usually mild and of short duration and suppression of the hypothalamicpituitary axis is therefore incomplete. As a result, serum cortisol concentrations increase in response to insulin-induced hypoglycemia in depressed patients with pseudo-cushing's syndrome, but not in patients with Cushing's syndrome [64]. This test is not recommended, because it can be unpleasant for the patient and should be avoided in those with a history of seizure disorder or coronary heart disease. (See "Insulin-induced hypoglycemia test"). Cortisol production rate The twenty-four hour cortisol production rate (CPR), measured by infusion of tracer amounts of nonradioactive cortisol isotopes, is high in patients with Cushing's syndrome. However, in a study of 28 patients with suspected Cushing's syndrome who had equivocal biochemical findings, this measurement did not offer any diagnostic advantage over existing tests such as 24-hour urinary cortisol excretion [65]. INFORMATION FOR PATIENTS Educational materials on this topic are available for patients. (See "Patient information: Cushing's syndrome" and see "Patient information: Cushing's syndrome treatment"). We encourage you to print or these topics, or to refer patients to our public web site which includes these and other topics. SUMMARY AND RECOMMENDATIONS Although there is seldom either clinical or laboratory ambiguity in patients with florid Cushing's disease, the diagnosis can be elusive in patients with early, mild disease. We agree with the 2008 Endocrine Society Guidelines and suggest the following approach [24]: We recommend that at least two first-line tests should be abnormal to establish the

10 Page 10 of 16 diagnosis of Cushing's syndrome [39]. We suggest late night salivary cortisol, urinary cortisol, and the low-dose dexamethasone suppression tests as first line tests. We suggest using conservative criteria to interpret the tests to maximize sensitivity. Urinary and salivary cortisol measurements should be obtained at least twice. The urinary cortisol excretion should be unequivocally increased (threefold above the upper limit of normal for the assay), or the diagnosis of Cushing's syndrome is uncertain and other tests should be performed. The diagnosis of Cushing's syndrome is confirmed when two tests are unequivocally abnormal. The patient should undergo additional evaluation if the test results are discordant or only slightly abnormal. If test results are normal, the patient does not have Cushing's syndrome unless it is extremely mild or cyclic. We do not suggest additional evaluation unless symptoms progress or cyclic Cushing's syndrome is suspected. Use of UpToDate is subject to the Subscription and License Agreement. REFERENCES 1. Weber, SL. Cushing's syndrome attributable to topical use of Lotrisone. Endocr Pract 1997; 3: Nutting, CM, Page, SR. Iatrogenic Cushing's syndrome due to nasal betamethasone: a problem not to be sniffed at!. Postgrad Med J 1995; 71: Hughes, JM, Hichens, M, Booze, GW, Thorner, MO. Cushing's syndrome from the therapeutic use of intramuscular dexamethasone acetate. Arch Intern Med 1986; 146: Mann, M, Koller, E, Murgo, A, et al. Glucocorticoid-like activity of megestrol. A summary of Food and DrugAdministration experience and a review of the literature. Arch Intern Med 1997; 157: Samaras, K, Pett, S, Gowers, A, et al. Iatrogenic Cushing's syndrome with osteoporosis and secondary adrenal failure in human immunodeficiency virus-infected patients receiving inhaled corticosteroids and ritonavir-boosted protease inhibitors: six cases. J Clin Endocrinol Metab 2005; 90: Olumide, YM, Akinkugbe, AO, Altraide, D, et al. Complications of chronic use of skin lightening cosmetics. Int J Dermatol 2008; 47: Oldenburg-Ligtenberg, PC, van der, Westerlaken MM. A woman with Cushing's syndrome after use of an Indonesian herb: a case report. Neth J Med 2007; 65: Cizza, G, Nieman, LK, Doppman, JL, et al. Factitious Cushing syndrome. J Clin Endocrinol Metab 1996; 81: Quddusi, S, Browne, P, Hirsch, IB. Cushing syndrome due to surreptitious glucocorticoid administration. Arch Intern Med 1998; 158: Kelly, CJ, Ogilvie, A, Evans, JR, et al. Raised cortisol excretion rate in urine and contamination by topical steroids. BMJ 2001; 322: Lin, C-L, Wu, T-J, Machacek, DA, et al. Urinary free cortisol and cortisone determined by high performance liquid chromatography in the diagnosis of Cushing's syndrome. J

11 Page 11 of 16 Clin Endocrinol Metab 1997; 82: Workman, RJ, Nicholson, WE, McCammon, DK. Factitious hypercortisoluria. J Clin Endocrinol Metab 1995; 80: Liddle, GW. Tests of pituitary-adrenal suppressibility in the diagnosis of Cushing's syndrome. J Clin Endocrinol Metab 1960; 20: Loosen, PT, Chambliss, B, DeBold, CR, et al. Psychiatric phenomenology in Cushing's disease. Pharmacopsychiatry 1992; 25: Pfohl, B, Sherman, B, Schlechte, J, Winokur, G. Differences in plasma ACTH and cortisol between depressed patients and normal controls. Biol Psychiatry 1985; 20: Pfohl, B, Sherman, B, Schlechte, J, Stone, B. Pituitary-adrenal axis rhythm disturbances in psychiatric depression. Arch Gen Psychiatry 1985; 42: Gold, PW, Loriaux, DL, Roy, A, et al. Responses to corticotropin-releasing hormone in the hypercortisolism of depression and Cushing's disease. Pathophysiologic and diagnostic implications. N Engl J Med 1986; 314: Amsterdam, JD, Maislin, G, Winokur, A, et al. The ocrh stimulation test before and after clinical recovery from depression. J Affect Disord 1988; 14: Kirkman, S, Nelson, DH. Alcohol-induced pseudo-cushing's disease: a study of prevalence with review of the literature. Metabolism 1988; 37: Groote Veldman, R, Meinders, AE. On the mechanism of alcohol-induced pseudo- Cushing's syndrome. Endocr Rev 1996; 17: Yanovski, JA, Nieman, LK, Doppman, JL, et al. Plasma levels of corticotropin-releasing hormone in the inferior petrosal sinuses of healthy volunteers, patients with Cushing's syndrome, and patients with pseudo-cushing's states. J Clin Endocrinol Metab 1998; 83: Arnaldi, G, Angeli, A, Atkinson, AB, et al. Diagnosis and complications of Cushing's syndrome: a consensus statement. J Clin Endocrinol Metab 2003; 88: Newell-Price, J, Trainer, P, Besser, M, Grossman, A. The diagnosis and differential diagnosis of Cushing's syndrome and pseudo-cushing's states. Endocr Rev 1998; 19: Nieman, LK, Biller, BM, Findling, JW, et al. The diagnosis of Cushing's syndrome: an Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab 2008; 93: Crapo, L. Cushing's syndrome: a review of diagnostic tests. Metabolism 1979; 28: Mengden, T, Hubmann, P, Muller, J, et al. Urinary free cortisol versus 17- hydroxycorticosteroids: a comparative study of their diagnostic value in Cushing's syndrome. Clin Investig 1992; 70: Hellman, L, Weitzman, ED, Roffwarg, H, et al. Cortisol is secreted episodically in Cushing's syndrome. J Clin Endocrinol Metab 1970; 30: Sederberg-Olsen, P, Binder, C, Kehlet, H, et al. Episodic variation in plasma corticosteroids in subjects with Cushing's syndrome of differing etiology. J Clin Endocrinol Metab 1973; 36: Van Cauter, E, Refetoff, S. Evidencefor two subtypes of Cushing's disease based on the analysis of episodic cortisol secretion. N Engl J Med 1985; 312: Elamin, MB, Murad, MH, Mullan, R, et al. Accuracy of diagnostic tests for Cushing's syndrome: a systematic review and metaanalyses. J Clin Endocrinol Metab 2008; 93: Yanovski, JA, Cutler, GB Jr, Chrousos, GP, Nieman, LK. Corticotropin-releasing hormone stimulation following low-dose dexamethasone administration: a new test to distinguish Cushing's syndrome from pseudo-cushing's states. JAMA 1993; 269: Batista, DL, Riar, J, Keil, M, Stratakis, CA. Diagnostic tests for children who are referred for the investigation of Cushing syndrome. Pediatrics 2007; 120:e Corcuff, JB, Tabarin, A, Rashedi, M, et al. Overnight urinary free cortisol determination: a screening test for the diagnosis of Cushing's syndrome. Clin Endocrinol 1998; 48:503.

12 Page 12 of Invitti, C, Giraldi, FP, De Martin, M, et al. Diagnosis and management of Cushing's syndromes: results of an Italian multicentre study. J Clin Endocrinol Metab 1999; 84: Carroll, BJ, Curtis, GC, Davies, BM, et al. Urinary free cortisol excretion in depression. Psychol Med 1976; 6: Mericq, MV, Cutler, GB Jr. High fluid intake increases urine free cortisol excretion in normal subjects. J Clin Endocrinol Metab 1998; 83: Kidambi, S, Raff, H, Findling, JW. Limitations of nocturnal salivary cortisol and urine free cortisol in the diagnosis of mild Cushing's syndrome. Eur J Endocrinol 2007; 157: Meinardi, JR, Wolffenbuttel, BH, Dullaart, RP. Cyclic Cushing's syndrome: a clinical challenge. Eur J Endocrinol 2007; 157: Blethen, SL, Chasalow, FI. Overnight dexamethasone suppression test: normal responses and the diagnosis of Cushing's syndrome. Steroids 1989; 54: Findling, JW, Raff, H, Aron, DC. The low-dose dexamethasone suppression test: a reevaluation in patients with Cushing's syndrome. J Clin Endocrinol Metab 2004; 89: Meikle, AW. Dexamethasone suppression tests: usefulness of simultaneous measurement of plasma cortisol and dexamethasone. Clin Endocrinol 1982; 16: Borcherding, SM, Baciewicz, AM, Self, TH. Update on rifampin drug interactions, II. Arch Intern Med 1992; 152: Castro, M, Elias, PC, Quidute, AR, et al. Out-patient screening for Cushing's syndrome: the sensitivity of the combination of circadian rhythm and overnight dexamethasone suppression salivary cortisol tests. J Clin Endocrinol Metab 1999; 84: Laudat, MH, Cerdas, S, Fournier, C, et al. Salivary cortisol measurement: a practical approach to assess pituitary-adrenal function. J Clin Endocrinol Metab 1988; 66: Bonnin, R, Villabona, C, Rivera, A, et al. Is salivary cortisol a better index than free cortisol in serum or urine for diagnosis of Cushing syndrome? Clin Chem 1993; 39: Raff, H, Raff, JL, Findling, JW. Late-night salivary cortisol as a screening test for Cushing's syndrome. J Clin Endocrinol Metab 1998; 83: Putignano, P, Toja, P, Dubini, A, et al. Midnight salivary cortisol versus urinary free and midnight serum cortisol as screening tests for Cushing's syndrome. J Clin Endocrinol Metab 2003; 88: Papanicolaou, DA, Mullen, N, Kyrou, I, Nieman, LK. Nighttime salivary cortisol: a useful test for the diagnosis of Cushing's syndrome. J Clin Endocrinol Metab 2002; 87: Yaneva, M, Mosnier-Pudar, H, Dugue, MA, et al. Midnight salivary cortisol for the initial diagnosis of Cushing's syndrome of various causes. J Clin Endocrinol Metab 2004; 89: Viardot, A, Huber, P, Puder, JJ, et al. Reproducibility of nighttime salivary cortisol and its use in the diagnosis of hypercortisolism compared with urinary free cortisol and overnight dexamethasone suppression test. J Clin Endocrinol Metab 2005; 90: Raff, H, Homar. PJ, Burns. EA. Comparison of two methods for measuring salivary cortisol. Clin Chem 2002; 48: Liu, H, Bravata, DM, Cabaccan, J, et al. Elevated late-night salivary cortisol levels in elderly male type 2 diabetic veterans. Clin Endocrinol (Oxf) 2005; 63: Newell-Price, J, Trainer, P, Perry, L, et al. A single sleeping midnight cortisol has 100 percent sensitivity for the diagnosis of Cushing's syndrome. Clin Endocrinol 1995; 43: Papanicolaou, DA, Yanovski, JA, Cutler, GB Jr, et al. A single midnight serum cortisol measurement distinguishes Cushing's syndrome from pseudo-cushing states. J Clin Endocrinol Metab 1998; 83:1163.

13 Page 13 of O'Brien, JT, Ames, D, Schweitzer, I. HPA axis function in depression and dementia: a review. Int J Geriatr Psychiatry 1993; 8: Duclos, M, Corcuff, JB, Pehourcq, F, Tabarin, A. Decreased pituitary sensitivity to glucocorticoids in endurance-trained men. Eur J Endocrinol 2001; 144: Duclos, M, Corcuff, JB, Roger, P, Tabarin, A. The dexamethasone-suppressed corticotrophin-releasing hormone stimulation test in anorexia nervosa. Clin Endocrinol (Oxf) 1999; 51: Martin, NM, Dhillo, WS, Banerjee, A, et al. Comparison of the dexamethasonesuppressed corticotropin-releasing hormone test and low-dose dexamethasone suppression test in the diagnosis of Cushing's syndrome. J Clin Endocrinol Metab 2006; 91: Gatta, B, Chabre, O, Cortet, C, et al. Reevaluation of the combined dexamethasone suppression-corticotropin-releasing hormone test for differentiation of mild cushing's disease from pseudo-cushing's syndrome. J Clin Endocrinol Metab 2007; 92: Reimondo, G, Bovio, S, Allasino, B, et al. The combined low-dose dexamethasone suppression corticotropin-releasing hormone test as a tool to rule out Cushing's syndrome. Eur J Endocrinol 2008; 159: Jackson, RV, Grice, JE, Jackson, AJ, Hockings, GI. Naloxone-induced ACTH release in man is inhibited by clonidine. Clin Exp Pharmacol Physiol 1990; 17: Torpy, DJ, Jackson, RV, Grice, JE, et al. Naloxone stimulation of ACTH secretion during petrosal sinus sampling in Cushing's syndrome. Clin Exp Pharmacol Physiol 1993; 20: Davis, BC, Gaitan, D, Loosen, PT, Orth, DN. Naloxone test distinguishes pituitary ACTHdependent Cushing's disease (CD) from major depressive disorder (MDD) and chronic alcoholism (ALC). J Invest Med 1995; 43(Suppl):259A. 64. Besser, GM, Edwards, CRW. Cushing's syndrome. Clin Endocrinol Metab 1972; 1: Samuels, MH, Brandon, DD, Isabelle, LM, et al. Cortisol production rates in subjects with suspected Cushing's syndrome: assessment by stable isotope dilution methodology and comparison to other diagnostic methods. J Clin Endocrinol Metab 2000; 85:22.

14 Page 14 of 16 GRAPHICS Episodic cortisol secretion in Cushing's syndrome Serum cortisol concentrations throughout the day in patients with different forms of Cushing's syndrome. There is episodic hormone release in both ACTH-dependent and ACTH-independent (adrenal adenoma) forms of the syndrome. To convert serum cortisol to nmol/l, multiply by 27.6). Data from Sederberg-Olsen, P, Binder, C, Kehlet, H, et al. J Clin Endocrinol Metab 1973; 36:906.

15 Page 15 of 16 Salivary cortisol concentrations in normal subjects, according to analytic method Radioimmunoassay of unextracted saliva Men (7 AM) 5.0 ± 0.4 Women (7 AM) 5.8 ± 0.5 Men and women (11 PM) 0.4 ± 0.1 Mean (SE), ng/ml Radioimmunoassay of unextracted saliva Men and women (9 AM) 6.0 ± Men and women (11 PM) 1.0 ± Obese men and women (9 AM) 5.3 ± Obese men and women (11 PM) 1.3 ± Range, ng/ml To convert salivary cortisol values to nmol/l multiply by Data from: Raff, H, Raff, JL, Findling, JW, J Clin Endocrinol Metab 1998; 83:2681 and Castro, M, Elias, PC, Quidute, AR, et al, J Clin Endocrinol Metab 1999; 84:878.

16 Page 16 of UpToDate, Inc. All rights reserved. Subscription and License Agreement Support Tag: [ecapp0604p.utd.com be8c9592e-6] Licensed to: Blanca Peruzzi