The endocrine diagnostic service. a clinical perspective

Transcription

1 The endocrine diagnostic service from immunoassay to chromatography and mass spectrometry a clinical perspective Sam Vasikaran APFCB Travelling Lecturer PathWest-Royal Perth Hospital Western Australia

2 The Asian and Pacific Federation of Clinical Biochemistry (APFCB) Mission: Working for the common good to advance clinical biochemistry in the Asia-Pacific region APFCB Asian Pacific Federation of Clinical Biochemistry

3 Current Membership 16 ordinary members National and area associations of clinical chemistry and lab medicine 14 Corporate members Population of APFCB members countries: 3.4 billion >50% of world s population APFCB Asian Pacific Federation of Clinical Biochemistry

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5 The endocrine laboratory diagnostic service

6 50% of type 2 diabetes in Australia is undetected 7.4% of Australians >25 years have type 2 diabetes (AusDiab Study) There is one undiagnosed with type 2 diabetes for every diagnosed person (2002 data). Of the undiagnosed type 2 diabetics ~80% have readily identifiable risk factors > 90% visit a doctor each year Yet, they are missed (that is half a million people)

7 The health profession is not good at diagnosing diabetes What is our role in this?

8 Case Study RCPA QAP Patient : 46 year old female Patient Location: GP Clinical Notes: past history of gestational DM Case Details: 75g glucose load given Plasma Glucose Fasting 5.8 mmol/l 60 minutes post glucose load 13.1 mmol/l 120 minutes post glucose load 5.6 mmol/l What is the interpretation of these results?

9 Case Study Patient : 46 year old female Patient Location: GP Clinical Notes: past history of gestational DM Case Details: 75g glucose load given Plasma Glucose Fasting 5.8 mmol/l 60 minutes post glucose load 13.1 mmol/l 120 minutes post glucose load 5.6 mmol/l Interpretation by participants (n ~ 100) Normal GTT Impaired fasting glycaemia Impaired Glucose tolerance (46% of responses) (40% of response) (14% of responses)

10 Case Study Patient : 46 year old female Patient Location: GP Clinical Notes: past history of gestational DM Case Details: 75g glucose load given Plasma Glucose Fasting 5.8 mmol/l 60 minutes post glucose load 13.1 mmol/l 120 minutes post glucose load 5.6 mmol/l Interpretation: Normal glucose tolerance test. Suggest repeat fasting glucose in one year s time MJA 2003; 179 (7):

11 We can measure blood glucose accurately and precisely Are we as good at using the measurement to make the correct diagnosis?

12 Change to HbA1c reporting A major challenge facing us in the immediate future Change over to reporting in IFCC units Educate doctors patients

13 Case Study Patient : 31 year old female Patient Location: GP Clinical Notes: Feeling tired and lethargic Results: Serum TFTs Free T4 20 pmol/l (9-19) TSH 0.02 mu/l ( ) Free T3 5.5 pmol/l ( ) What is the interpretation of these results?

14 Case Study Patient : 31 year old female Patient Location: GP Clinical Notes: Feeling tired and lethargic Results: Serum TFTs Free T4 20 pmol/l (9-19) TSH 0.02 mu/l ( ) Free T3 5.5 pmol/l ( ) What is the interpretation of these results? Δ Hyperthyroidism?

15 Case Study Patient : 31 year old female Patient Location: GP Clinical Notes: Feeling tired and lethargic Results: Serum TFTs Free T4 20 pmol/l (9-19) TSH 0.02 mu/l ( ) Free T3 5.5 pmol/l ( ) What is the interpretation of these results? Δ Hyperthyroidism, unless the patient is pregnant in which case these results may be normal. Repeat TFTs in 6 weeks time

16 First-trimester trimester reference intervals derived from Western Australian women Gilbert RM et al. MJA 2008; 189 (5): Serum TSH and free β-hcg in 1817 antibody-negative women, by week of gestation TSH Reference Interval ( )

17 We can measure TFTs accurately and precisely (most of the time) But, if we do not use the appropriate reference intervals we could get the diagnosis wrong

18 Thyroglobulin Tumour marker for monitoring differentiated thyroid carcinoma post total-thyroidectomy Propensity for interference by TgAb ( false ve) heterophile antibodies ( false +ve) NACB recommendation: When TgAb is present, undetectable Tg by immunoassays should not be reported Method to method bias attributable to standardisation and to assay specificity for circulating Tg isoforms

19 Quantification of Thyroglobulin, a Low-Abundance Serum Protein, by Immunoaffinity Peptide Enrichment and Tandem Mass Spectrometry Hoofnagle AN et al. Clin Chem 2008;54: LCMSMS to quantify tumor antigens and other low-proteins in human serum Immunoaffinity peptide enrichment LCMSMS can detect...thyroglobulin while also digesting the endogenous immunoglobulins that can interfere with immunoassays Detection limit for endogenous thyroglobulin in serum µg/l

20 Thyroglobulin Sensitivity of current immunoassays is a major issue Detectable post operative serum Tg indicates presence of remnant or tumour thyroid tissue However, undetectable serum Tg during does not guarantee disease free status Insensitivity of current assays (functional sensitivity 1-2ug/L) may prevent detection of low, clinically significant Tg concentration TSH stimulated Tg testing is recommended to unmask occult disease in such patients

21 Monitoring Tg in a sensitive immunoassay has comparable sensitivity ity to rhtsh-stimulated Tg in follow-up of DTC patients J Clin Endocrinol Metab Jan;92(1):82-7. When a sufficiently sensitive Tg assay is used, DTC patients with a T4- suppressed serum Tg <0.1 ug/l rarely have a raised TSH-stimulated Tg sensitive serum Tg assays may render TSH stimulation unnecessary. Mazzaferri EL, et al JCEM 2003; 88: 4508 Functional sensitivity 0.1 ug/l Such an automated assay is now available

22 Testosterone in men What is normal? the lower limit of the normal range for total testosterone level in healthy young men is 300 ng/dl (10.4 nmol/l) Testosterone Therapy in Adult Men with Androgen Deficiency Syndromes: An Endocrine Society Clinical Practice Guideline 2006 Testosterone reference interval for reproductively normal men (age, yr) by GC/MS: (nonparametric): nmol/l Ken Sikaris et al J Clin Endocrinol Metab 2005; 90(11):

23 Relationship between age and hormones Wu, F. C. W. et al. J Clin Endocrinol Metab 2008;93: Copyright 2008 The Endocrine Society

24 The Endocrine Society of Australia consensus guidelines for androgen prescribing Biochemical evaluation of the diagnosis of androgen deficiency in men with clinical features consistent with hypogonadism* MJA 2000; 172: Testosterone LH Diagnosis <8 nm High Androgen deficiency (hypergonadotropic hypogonadism ) <8 nm Not high Androgen deficiency (hypogonadotropic hypogonadism ) 8-15 nm High Androgen deficiency (Leydig cell failure) 8-15 nm Not high Androgen deficiency not confirmed >20 nm Any Excludes androgen deficiency >30 nm** High Androgen resistance *There is necessarily an arbitrary component to this type of table. It is based on current experience and should be subject to changes according to further clinical evidence.

25 Serum testosterone nmol/l is equivocal; free T or bioavailable T is recommended Utility, limitations, and pitfalls in measuring testosterone: an Endocrine Society position statement. Rosner W et al, J Clin Endocrinol Metab 2007;92(2):

26 Toward a definition of male hypogonadism: how much testosterone does a man really need? Finkelstein ENDO 09 Abstract RCT 237 healthy men, age Baseline serum T nm Received goserelin 3.6mg/month Randomised to one of 5 treatments: T gel (4 doses) or placebo daily for 16 wks Control group placebo injections and placebo gel. courtesy John Walsh

27 How much testosterone does a man really need? Finkelstein ENDO09 Serum T (Mean ± SE) Group ± 0.1 Group ± 0.4 Group ± 1.0 Group ± 1.1 Group ± 2.1 Controls 20.3 ± 1.0

28 How much testosterone does a man really need? Finkelstein ENDO09 Serum T (Mean ± SE) Group ± 0.1 Group ± 0.4 Group ± 1.0 Group ± 1.1 Group ± 2.1 Controls 20.3 ± 1.0 fat mass <13.9

29 How much testosterone does a man really need? Finkelstein ENDO09 Serum T (Mean ± SE) Group ± 0.1 Group ± 0.4 Group ± 1.0 Group ± 1.1 Group ± 2.1 Controls 20.3 ± 1.0 fat mass <13.9 lean mass <3.5

30 How much testosterone does a man really need? Finkelstein ENDO09 Serum T (Mean ± SE) fat mass lean mass bone resorption Group ± 0.1 Group ± 0.4 Group ± 1.0 Group ± 1.1 <13.9 <3.5 <6.9 Group ± 2.1 Controls 20.3 ± 1.0

31 How much testosterone does a man really need? Finkelstein ENDO09 Serum T (Mean ± SE) fat mass lean mass bone resorption ED Group ± 0.1 Group ± 0.4 Group ± 1.0 Group ± 1.1 <13.9 <3.5 <6.9 <3.5 Group ± 2.1 Controls 20.3 ± 1.0

32 How much testosterone does a man really need? Finkelstein ENDO09 Serum T (Mean ± SE) fat mass lean mass bone resorption ED libido Group ± 0.1 Group ± 0.4 Group ± 1.0 Group ± 1.1 <13.9 <3.5 <6.9 <3.5 Group ± 2.1 Controls 20.3 ± 1.0 <30 The testosterone concentration below which testosterone administration improves outcomes is unknown and may vary among individuals and among target organs Testosterone Therapy in Adult Men with Androgen Deficiency Syndromes: An Endocrine Society Clinical Practice Guideline

33 Patient : 13 year old female Patient Location: GP Clinical Notes: Polymenorrhoea Testosterone in women Case study Serum Ref. Int E2 180 pmol/l Prg 4 nmol/l <2 FSH 7 U/L 2-10 LH 3 U/L 2-10 Testosterone (ICMA) 5.0 nmol/l <2.6 Case Details: Not pregnant. No medications of note. Results not typical of PCOS; DHEAS, 17OHP, androstenedione to follow

34 Case study Patient : 13 year old female Patient Location: GP Clinical Notes: Polymenorrhoea Serum Ref. Int E2 180 pmol/l Prg 4 nmol/l <2 FSH 7 U/L 2-10 LH 3 U/L 2-10 Testosterone (ICMA) 5.0 nmol/l <2.6 Testosterone (LCMSMS) 0.3 nmol/l (< 2.0)

35 More specific testosterone assay = less diagnostic sensitivity? Answer = Hormone profiling?

36 Immunoassays for Testosterone in Women: Better than a Guess? Clin Chem 2003;49: Editorial by David Herold and Robert Fitzgerald In the case of testosterone, the immunoassays do not work in healthy females and fail miserably when used in potentially diseased females

37 Calculated free testosterone(using T and SHBG)..the most useful marker of hyperandrogenaemia in women can be used in concert with clinical endpoints. Utility, limitations, and pitfalls in measuring testosterone: an Endocrine Society position statement. Rosner W et al, J Clin Endocrinol Metab 2007;92(2):

38 18 year old female Location: Medical ward. Case Study Clinical notes: Amenorrhoea, nausea and vomiting. Result Unit RI Prolactin 3145 mu/l <500 mu/l All reproductive hormones were within reference intervals and hcg negative. What is the interpretation of these results?

39 Case Study 18 year old female Location: Medical ward. Clinical notes: Amenorrhoea, nausea and vomiting. Result Unit RI Prolactin 3145 mu/l <500 mu/l Previous Result: (a few days ago in ED) Prolactin 195

40 Case Study 18 year old female Location: Medical ward. Clinical notes: Amenorrhoea, nausea and vomiting. Result Unit RI Prolactin 3145 mu/l <500 mu/l Previous Result: (a few days ago in ED) Prolactin 195 Increase in prolactin due to medication (anti-emetic)

41 Macroprolactin Figure 1. HPLC separation of 3 patients with PEG recovery ranging between 70 % and 90 % Prolactin (mu/l) Figure 2. HPLC separation of 2 patients with PEG precipitation recoveries <10% Volume (ml) Prolactin (mu/l) Volume (ml)

42 GP referral to Endocrinologist This patient has macroprolactinaemia. For appropriate further management

43 Case study Patient : 67 year old male Patient Location: ICU Clinical Notes: Acute abdomen Case Details: Adrenal mass detected incidentally on ultrasound scan

44 Case study Patient : 67 year old male Patient Location: ICU Clinical Notes: Acute abdomen Case Details: Adrenal mass detected incidentally on ultrasound scan Results: Serum cortisol 1180 nmol/l ( ) Etracted RIA method

45 Case study Patient was on intravenous hydrocortisone Prior to undertaking any endocrine investigations consider the impact of medications (ideally interfering medications should be ceased) Drug interference would be present whatever the method

46 Urine cortisol to extract or to not extract? Extracted immunoassay (RI <330 nmol/l) Non extracted Automated immunoassay (Urinary corticoids ) (RI <(900 nmol/l) Kikuchi et al. found that patients with adrenal dependent CS had elevated excretions of 11- deoxycortisol, 18-hydroxycortisol and cortisone metabolites as well as cortisol. Extracted HPLC (RI <170 nmol/l) the question remains whether an accurate and specifc urine cortisol determination, such as that obtained by HPLC, necessarily improves the diagnosis of CS Ching SY et al. Ann Clin Biochem 2006; 43:

47 Diagnosis of primary aldosteronism Screening test Aldosterone Renin Ratio (ARR) Sensitivity / specificity varies with Pre-analytical factors Medications (major issue) Hypokalemia (reduces aldosterone) Diagnostic test?

48 18-hydroxycortisol Useful for differentiating adrenal adenoma (GSH) from bilateral hyperplasia (BAH) Is immunoassay that detects cross-reacting steroid better than GC-MS for discriminating adenoma from BAH? Reynolds RM et al Eur J Endocrinol 205;152:903-7

49 Adrenal vein sampling (AVS) Gold standard to distinguish b/w adenoma and bilateral hyperplasia Involves: collecting samples from adrenal veins Confirm adequate adrenal vein catheterisation by cortisol level Aldo:cortisol ratios used in interpretation Mayo-Smith W W et al. Radiographics 2001;21: by Radiological Society of North America

50 cortisol measurement during adrenal vein sampling to confirm successful catheterisation SITE Cortisol Collection nmol/l Date Time Left Adrenal /12/07 10:30 Peripheral /12/07 10:31 Right Adrenal /12/07 10:32 Peripheral /12/07 10:33 Right Adrenal /12/07 10:34 Peripheral /12/07 10:35

51 Intra procedure cortisol measurement during adrenal vein sampling to confirm successful catheterisation SITE Cortisol Collection nmol/l Date Time Left Adrenal /12/07 10:30 Peripheral /12/07 10:31 Right Adrenal /12/07 10:32 Peripheral /12/07 10:33 Right Adrenal /12/07 10:34 Peripheral /12/07 10:35 Right Adrenal /12/07 11:06 Peripheral /12/07 11:07

52 Adrenal vein sampling to confirm unilateral aldosterone secretion SITE Aldosterone Cortisol Ald/Cor Collection pmol/l nmol/l Ratio Date Time ==== ======== ===== ===== ======== Left Adrenal /12/07 10:30 * Peripheral /12/07 10:31 Right Adrenal /12/07 10:32 Peripheral /12/07 10:33 Right Adrenal /12/07 10:34 Peripheral /12/07 10:35 Right Adrenal /12/07 11:06 * Peripheral /12/07 11:07 High IVC /12/07 11:18 Peripheral /12/07 11:19 Low IVC /12/07 11:22 Peripheral /12/07 11:23

53 PLASMA FREE METANEPHRINE COMMENTS FOR BORDERLINE RESULTS Increases in plasma free metanephrines of this magnitude are not typical of pheochromocytoma/paraganglioma. Diet (caffeine, patient non-fasting), drugs (beta blockers, tricyclic antidepressants, phenoxybenzamine) and stress may increase plasma free metanephrines levels. Repeat plasma metanephrines 2 weeks after withdrawal of possible interfering substances.

54 How often are patients with borderline plasma mets retested? * 20%-30% of patients with phaeochromocytoma have borderline-elevated plasma free metanephrine results WAS PLASMA METS REPEATED? Not Stated 7% YES 21% NO 72% Audit of borderline raised plasma free metanephrines (n=134) in Perth to examine how many of them undergo repeat testing to exclude phaeochromocytoma.

55 A misunderestimated comment? Increases in plasma free metanephrines of this magnitude are not typical of pheochromocytoma/paraganglioma. Diet (caffeine, patient non-fasting), drugs (beta blockers, tricyclic antidepressants, phenoxybenzamine) and stress may increase plasma free metanephrines levels. Repeat plasma metanephrines 2 weeks after withdrawal of possible interfering substances. A better comment? Paheochromocytoma not excluded. 20% of patients with phaeochromocytoma have borderline elevated levels. However, diet (caffeine, patient non-fasting), drugs (beta blockers, tricyclic antidepressants, phenoxybenzamine) and stress may increase plasma free metanephrines levels. Repeat plasma metanephrines 2 weeks after withdrawal of possible interfering substances.

56 Case study Patient : 71 year old female Patient Location: Endocrine Clinic Clinical Notes: Borderline elevated mets. To exclude phaeo Clonidine suppression test Pre Post Plasma nor-metadrenaline (free) pmol/l (< 780) Plasma metadrenaline (free) pmol/l (< 300)

57 PTH Intact assays used Automated assays available and popular Issues: Standardisation Reference interval needs to be set appropriately For the assay For the population (including age, sex, etc) Using vitamin D replete population

58 Establishing a PTH reference range Effect of age on normal PTH DPC Immulite 2000 (old) PTH assay Reference interval based on 2.5 & 97.5 percentiles All cases All ages < 55 years years

59 Establishing PTH reference interval Effect of vitamin D status of reference population DPC Immulite 2000 (old) PTH assay 14 All subjects (n=224) PTH pmol/l 8 6 PTH Ref Interval all subjects [224] Ref Interval 25D replete subjects-69% [25 D > 50 nmol/l] Vit D nmol/l Vitamin D status and redefining serum PTH reference range in the elderly JCEM 2001; 7:

60 Vitamin D measurement HPLC DiaSorin IDS Nichols Advantage Bias between different assays Underlined figure indicates suggested assay specific cut-off for vitamin D deficiency. Glendenning et al Ann Clin Biochem 2006;43:23-30

61 Whole PTH assay Claimed to: accurately measure the biologically active PTH (1-84) and not the 7-84 fragment recognised by intact assays will be especially useful in renal failure Journal of Bone and Mineral Research 2001; 16: Quantification of human 1-84 PTH in serum and plasma by immunocapture-in-situ digestion LC-MS/MS Ravinder singh

62 New use for an old assay OSTEOCALCIN Uncarboxylated osteocalcin, a bone formation marker secreted by osteoblasts, regulates insulin production and insulin sensitivity in the body Both in vitro studies and in vivo studies on knockout mice show that osteocalcin stimulates beta cells to produce insulin and promotes the growth of new beta cells in the pancreas Karsenty G et al. Osteocalcin signals adipocytes to produce adiponectin, a metabolic hormone that regulates insulin sensitivity

63 Major analytical issue with immunoassays for osteocalcin Stability, fragments/different forms Standardisation of assays/recognition of fragments Someone somewhere is working on a LCMSMS assay for osteocalcin