WARD INSTRUCTIONS WEBSITE

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1 DEPARTMENT OF CLINICAL CHEMISTRY NEW CROSS HOSPITAL WOLVERHAMPTON WARD INSTRUCTIONS WEBSITE Edition 1.1 SOP E1.120P.CHE Date issued: June 2016 Review interval: Authorised copy: Printed copies Author Location of printed copies Number of pages including the front page Biennial Q-pulse document and intranet R. Gama Q-pulse document and Hospital Intranet 18 Document number: E1.120P.CHE Page: 1 of 16

2 CONTENTS 1. ORAL GLUCOSE TOLERANCE TEST FOR DIAGNOSIS OF GROWTH HORMONE (GH) EXCESS 2. LACTOSE TOLERANCE TEST 3. OVERNIGHT DEXAMETHASONE SUPPRESSION TEST 4. SHORT SYNACTHEN TEST FOR LATE ONSET CONGENITAL ADRENAL HYPERPLASIA 5. SHORT SYNACTHEN TEST FOR ADRENOCORTICAL INSUFFICIENCY 6. WATER DEPRIVATION TEST Document number: E1.120P.CHE Page: 2 of 16

3 1.0 ORAL GLUCOSE TOLERANCE TEST FOR DIAGNOSIS OF GROWTH HORMONE (GH) EXCESS 1.0 Test Utility Diagnosis of acromegaly 2.0 Patient Selection Test indicated in patients with suspected acromegaly 3.0 Contra-indications None 4.0 Cautions Known diabetics: Should only be used in mild diabetes otherwise consider measuring only serum IGF-1 and random GH 5.0 Preparation 5.1 Fast for 12 hours, drink water only. (Prescribed medicines are allowed unless they must be taken with food). 5.2 Order Polycal (Nutricia Clinical) from pharmacy 5.4 Other requirements: intravenous cannula, normal saline to keep cannula patent, serum gel brown top and fluoride EDTA yellow top sample tubes. 6.0 Test Protocol 6.1 Confirm that the patient has fasted, 6.2 Insert an intravenous cannula (optional) 6.3 Take a baseline venous blood sample for GH and IGF-1 into a serum gel tube brown top bottle and for glucose into a fluoride EDTA yellow top bottle 6.4 If cannulated: Inject normal saline to keep cannula patent 6.5 For adults give 113 ml chilled Polycal (Nutricia Clinical), to which ml water has been added. Use a clean measuring cylinder. The patient should consume within 5 minutes 6.6 If cannulated: collect 1ml of blood and discard prior to collection of blood samples and after collection of blood samples inject normal saline to keep cannula patent 6.7 Take further venous blood samples for growth hormone into a serum gel tube brown top bottle and for glucose into a fluoride EDTA yellow top bottle 30, 60, 90 and 120, minutes after consumption of Polycal. Document number: E1.120P.CHE Page: 3 of 16

4 6.8 Make sure that patient s name, hospital number, DoB and time of sample are written on samples and request form 6.9 Send completed test to laboratory in one bag. 7.0 Interpretation 7.1 Normal Response GH normally suppresses to less than 0.4 ug/l after a glucose load. Serum IGF-1 concentrations are sex and age dependent. Fasting glucose <7.0 and 2 hour <7.8 mmol/l 7.2 Abnormal response Failure of GH to suppress below 0.4 ug/l is highly suggestive of active acromegaly. The combination of GH non-suppression and an unequivocally elevated IGF-1 is virtually diagnostic of active acromegaly Acromegaly may be complicated by impaired glucose tolerance (IGT) or diabetes Diabetes: Fasting glucose 7.0 or 2 hour 11.1 mmol/l IGT: Fasting < 7.0 and 2 hour mmol/l Document number: E1.120P.CHE Page: 4 of 16

5 2.0 LACTOSE TOLERANCE TEST (LTT) 1.0 Test Utility Investigation of lactose intolerance Day 1: Lactose tolerance test Day 2: Glucose tolerance test if LTT abnormal 2.0 Patient Selection Test indicated in patients with suspected lactose intolerance 3.0 Contra-indications Patients with periodic hypokalaemic paralysis 4.0 Cautions 4.1 Don t perform the LTT or GTT during acute illness (including infection and less than 2 weeks after major surgery). 3.2 Drugs known to affect glucose tolerance include beta blockers, corticosteroids, diazoxide, loop diuretics, thiazide diuretics, nicotinic acid, oestrogens, progesterone, phenytoin and metformin. Day Preparation 5.1 Fast for 12 hours, drink water only. (Prescribed medicines are allowed unless they must be taken with food). 5.2 Order 50g lactose solution from pharmacy 5.4 Other requirements: intravenous cannula, normal saline to keep cannula patent, fluoride EDTA yellow top sample tubes. 6.0 Test Protocol 6.10 Confirm that the patient has fasted, 6.11 Warn the patient of possible gastrointestinal side-effects including nausea, abdominal pain and diarrhoea 6.12 Insert an intravenous cannula (optional) 6.13 Take a baseline venous blood sample for glucose into a fluoride EDTA yellow top bottle 6.14 If cannulated: Inject normal saline to keep cannula patent 6.15 Give solution containing 50g of lactose. The patient should consume within 5 minutes Document number: E1.120P.CHE Page: 5 of 16

6 6.16 If cannulated: collect 1ml of blood and discard prior to collection of blood samples and after collection of blood samples inject normal saline to keep cannula patent 6.17 Take further venous blood samples for glucose into a fluoride EDTA yellow top bottle 30, 60, 90 and 120, minutes after consumption of lactose 6.18 Symptoms must be recorded at each time point if asymptomatic write none 6.19 Make sure that patient s name, hospital number, DoB and time of sample are written on samples and request form 6.20 Send completed test to laboratory in one bag. 8.0 Interpretation Normal Response A rise in plasma glucose >1.1 mmol/l An average glucose increase of 2.7 mmol/l occurs in normal subjects Abnormal response: A failure in glucose to rise following lactose and abdominal symptoms (pain, borborygmi, diarrhoea) is consistent with lactose intolerance. Proceed to GTT Day Preparation 8.1 Fast for 12 hours, drink water only. (Prescribed medicines are allowed unless they must be taken with food). 8.2 Order Polycal (Nutricia Clinical) from pharmacy 8.3 Other requirements: intravenous cannula, normal saline to keep cannula patent, fluoride EDTA yellow top sample tubes. 9.0 Test Protocol 9.1 Confirm that the patient has fasted 9.2 Insert an intravenous cannula (optional) 9.3 Take a baseline venous blood sample for glucose into a fluoride EDTA yellow top bottle 9.4 If cannulated: Inject normal saline to keep cannula patent 9.5 Give 113 ml chilled Polycal (Nutricia Clinical), to which ml water has been added. Use a clean measuring cylinder. The patient should consume within 5 minutes. The patient should consume within 5 minutes 9.6 If cannulated: collect 1ml of blood and discard prior to collection of blood samples and after collection of blood samples inject normal saline to keep cannula patent 9.7 Take further venous blood samples for glucose into a fluoride EDTA yellow top bottle 30, 60, 90 and 120, minutes after consumption of polycal Document number: E1.120P.CHE Page: 6 of 16

7 9.8 Make sure that patient s name, hospital number, DoB and time of sample are written on samples and request form 9.9 Send completed test to laboratory in one bag. 10 Interpretation Normal Response A rise in plasma glucose >1.1 mmol/l Abnormal response: Day 1: A failure in glucose to rise following lactose and abdominal symptoms (pain, borborygmi, diarrhoea) is consistent with lactose intolerance and Day 2: Either A normal response following glucose (and abnormal LTT) is highly suggestive of primary lactose intolerance. Or A failure in glucose to rise in GTT (and LTT) suggests lactose intolerance due to generalised malabsorption. 11. Notes 11.1 On day 1: Patient should be kept in department until results available to book, if appropriate, a GTT 11.2 No need to proceed to day 2 tests if normal response to lactose ingestion. Document number: E1.120P.CHE Page: 7 of 16

8 3.0 OVERNIGHT DEXAMETHASONE SUPPRESSION TEST 1.0 Test Utility Screening test for Cushing s Syndrome 2.0 Patient Selection Test indicated in patients with suspected Cushing s Syndrome 3.0 Contra-indications None 4.0 Cautions None 5.0 Preparation 5.1 Order 2mg of dexamethasone from pharmacy 5.2 Serum gel brown top sample tube. 6.0 Test Protocol 6.21 Outpatient test 6.22 The patient takes 2mg of dexamethasone orally at 23.00h Collect a venous blood sample for cortisol into a serum gel tube brown top bottle at exactly the next morning Make sure that patient s name, hospital number, DoB and time of sample are written on sample and request form 6.25 Send completed test to laboratory in one bag. 9.0 Interpretation 7.1 Normal Response Cortisol normally suppresses to less 50 nmol/l 7.2 Abnormal response Failure of cortisol to suppress <50nmol/L is suggestive of Cushing s Syndrome and warrants further investigation. False positives may occur in: Patients on hepatic enzyme inducing drugs e.g. anticonvulsants and rifampicin which may rapidly metabolise dexamethasone Document number: E1.120P.CHE Page: 8 of 16

9 In women on oestrogen therapy including oral contraceptives, tamoxifen, serum cortisol may fail to suppress due to increased cortisol binding globulin Stress and depression (due to the development of reversible glucocorticoid resistance), and chronic alcohol abuse. Document number: E1.120P.CHE Page: 9 of 16

10 4.0 SHORT SYNACTHEN TEST FOR LATE ONSET CONGENITAL ADRENAL HYPERPLASIA 1.0 Test Utility Assessment of virilism 2.0 Patient Selection Test indicated in patients suspected of late-onset congenital adrenal hyperplasia 3.0 Contra-indications Allergy to synacthen 4.0 Cautions None 5.0 Preparation 5.1 Preferably commence test at 09.00h 5.2 If applicable perform test in early follicular phase of menstrual cycle. 5.3 Ensure patient is not on steroids or cyproterone acetate 5.3 Order 250 µg of synacthen (1 ampoule) from pharmacy 5.4 Other requirements: intravenous cannula, normal saline to keep cannula patent, serum gel brown top sample tubes 6.0 Test Protocol 6.26 Insert an intravenous cannula (optional) 6.27 Take a baseline venous blood sample for cortisol, 17-hydroxyprogesterone, progesterone, testosterone, SHBG, androstenedione, dehydroepiandrostenedione sulphate, prolactin, TFTs, LH, FSH and oestradiol into two serum gel tube brown top bottles 6.28 If cannulated: inject normal saline to keep cannula patent 6.29 Administer 250 µg Synacthen IV (or IM) at 0 minutes 6.30 If cannulated: Collect 1ml of blood and discard prior to collection of blood samples and after collection of blood samples inject normal saline to keep cannula patent 6.31 Take further venous blood samples for cortisol, 17-hydroxyprogesterone, progesterone, into two serum gel tube brown top bottles 30 and 60 minutes after administration of synacthen 6.32 Make sure that patient s name, hospital number, DoB and time of sample are written on samples and request form Document number: E1.120P.CHE Page: 10 of 16

11 6.33 Send completed test to laboratory in one bag Interpretation 7.1 Normal Response Cortisol: Incremental increase of at least 160 nmol/l over baseline. Peak response of at least 450 nmol/l L 17 Hydroxyprogesterone: Basal less than 10nmol/L. Peak response less than 35 nmol/l 7.2 Abnormal response Exaggerated 17OH-Progesterone responses with or without blunted cortisol responses to synacthen are compatible with a diagnosis of late-onset congenital adrenal hyperplasia. Document number: E1.120P.CHE Page: 11 of 16

12 5.0 SHORT SYNACTHEN TEST FOR ADRENOCORTICAL INSUFFICIENCY 1.0 Test Utility Assessment of adrenocortical reserve 2.0 Patient Selection Test indicated in patients suspected of adrenal failure 3.0 Contra-indications Allergy to synacthen 4.0 Cautions None 5.0 Preparation 5.1 Patients should not be on steroids (see notes below). 5.3 Order 250 µg of synacthen (1 ampoule) from pharmacy 5.4 Other requirements: intravenous cannula, normal saline to keep cannula patent, serum gel brown top sample tubes 6.0 Test Protocol 6.34 Preferably commence test at 09.00h 6.35 Insert an intravenous cannula (optional) 6.36 Take a baseline venous blood sample for cortisol into a serum gel tube brown top bottle 6.37 If cannulated: inject normal saline to keep cannula patent 6.38 Administer 250 µg Synacthen IV (or IM) at 0 minutes 6.39 If cannulated: Collect 1ml of blood and discard prior to collection of blood samples and after collection of blood samples inject normal saline to keep cannula patent 6.40 Take further venous blood sample for cortisol into a serum gel tube brown top bottle 30 and 60 minutes after administration of synacthen 6.41 Make sure that patient s name, hospital number, DoB and time of sample are written on samples and request form 6.42 Send completed test to laboratory in one bag Interpretation 7.1 Normal Response Incremental increase of 160 nmol/l. Document number: E1.120P.CHE Page: 12 of 16

13 Peak response of at least 450 nmol/l L 7.2 Abnormal response Failure to respond to synacthen indicates primary or secondary adrenal failure or suppression of the hypothalamic-pituitary-adrenal (HPA) axis due to exogenous steroids. Further investigations are then indicated to differentiate between primary and secondary adrenal failure. 8.0 NOTES 8.1 Detailed history of steroid therapy required to evaluate possibility of HPA axis suppression. 8.2 The patient must not be on hydrocortisone or related steroids (e.g. prednisolone) as these cross-react in the cortisol assay. Stop low dose replacement dose steroids 24hours prior to synacthen test. May resume steroids after completion of test. When steroids cannot be stopped, e.g. patients on large doses of steroids or impending addisonian crisis, the Synacthen test should be performed under equivalent dosage dexamethasone cover at least two days before the test. 8.3 Acute secondary adrenal failure may be associated with normal cortisol responses to synacthen 8.4 False positives may occur in patients with low cortisol binding globulin such as in critically patients. Document number: E1.120P.CHE Page: 13 of 16

14 6.0 WATER DEPRIVATION TEST 1.0 Test Utility In the differential diagnosis of unexplained polyuria 2.0 Patient Selection Test indicated in patients with suspected diabetes insipidus 3.0 Contra-indications 3.1 Dehydrated patient check paired serum and urine osmolalities 3.2 Spot urine osmolality >750 mmol/kg 4.0 Cautions 4.1 Exclude other causes of polyuria (and urinary frequency) including diabetes mellitus, hypercalcaemia, hypokalaemia, hypothyroidism, urinary infections, chronic renal failure and therapy with carbamazepine, chlorpropamide or lithium therapy. 4.2 Ensure glucocorticoid replete 4.3 Ensure normal thyroid function or adequately replaced with thyroxine 5.0 Preparation 5.1 Inform the laboratory at least one 1 week prior to undertaking the test. 5.2 If on desmopressin, it should be stopped 24h prior to test 5.3 Patients must be advised not to smoke or consume caffeine (tea and coffee) on the morning of the test. 5.4 Order desmopressin from pharmacy 5.5 Other requirements: intravenous cannula, normal saline to keep cannula patent, serum gel brown top sample tubes and white top universal bottle, accurate weighing scales and measuring cylinders 6.43 Test Protocol Water deprivation 6.44 Test must be clinically supervised to ensure compliance with fluid deprivation 6.45 No food or water except for dry lunch throughout Document number: E1.120P.CHE Page: 14 of 16

15 6.46 Collect 10 mls of urine into universal white bottle and discard the remainder 6.47 Insert an intravenous cannula 6.48 Take a baseline venous blood sample for osmolality and U&Es into a serum gel tube brown top bottle 6.49 Inject normal saline to keep cannula patent 6.50 Weigh the patient and record 95% of weight (5% weight loss) 6.51 Commence fluid restriction for 8 hours but may be terminated early (see below) 6.52 Then every hour measure and record urine volume, collect 10 ml aliquot of urine into universal white bottle, collect baseline venous blood sample for osmolality and U&Es into a serum gel tube brown top bottle and then weigh the patient 6.53 Make sure that patient s name, hospital number, DoB and time of collection of urine and blood samples are written on samples and request form and send urine and blood samples test to the laboratory in one RED Urgent bag 6.54 If patient loses >5% body weight during water deprivation measure plasma osmolality. If plasma osmolality >300 mmol/l give desmopressin (see below) and allow patient to drink If patient loses >5% body weight during water deprivation measure plasma osmolality. If plasma osmolality <295 mmol/l patient was probably fluid overloaded prior to test. Consider continuing with fluid deprivation but seek advice from requesting Consultant or Duty Biochemist If plasma osmolality >300 mmol/l give desmopressin (see below) and allow patient to drink If urine osmolality >750mOsm/kg on two consecutive occasions during water deprivation terminate test as normal response Desmopressin Test 6.58 After 8 hours or when patient dehydrated (serum osmolality >300mmol/L) inappropriately dilute urine (urine osmolality < 600mOsm/kg) give 2 µg desmopressin IM Allow access to fluid up to 1.5 times the volume of urine passed during dehydration phase Then every hour for the next 4 hours measure and record urine volume, collect 10 ml aliquot of urine into universal white bottle, collect baseline venous blood sample for osmolality and U&Es into a serum gel tube brown top bottle 12.0 Interpretation 7.1 Normal Response Urine osmolality rises and urine volume falls during water deprivation. Urine osmolality will concentrate to >600mOsm/kg and urine flow rate will fall to <0.5ml/min. The U:P osmolality ratio will be >2 at the end of the test. Plasma osmolality remains <295 mmol/l. Document number: E1.120P.CHE Page: 15 of 16

16 7.2 Abnormal response Cranial diabetes insipidus: Urine osmolality remains inappropiately low and urine volume inappropriately high in the presence of plasma hyperosmolality. Urine concentrates normally after desmopressin Nephrogenic diabetes insipidus: Urine osmolality remains inappropiately low and urine volume inappropriately high in the presence of plasma hyperosmolality. Urine fails to concentrate after desmopressin. Primary polydipsia: Low or low/normal serum sodium and osmolality on a random sample is suggestive of primary polydispsia Normal responses providing adequate hydration is achieved during test. Many patients however are fluid overloaded at the start of the test, fluid deprivation of >8h may be required Notes With prolonged polyuria renal urine concentrating ability may be impaired due to wash out of osmotic gradient within the renal medulla. Document number: E1.120P.CHE Page: 16 of 16