CHOLESTEROL IS THE PRECURSOR OF STERIOD HORMONES

Transcription

1 HORMONES OF ADRENAL CORTEX R. Mohammadi Biochemist (Ph.D.) Faculty member of Medical Faculty

2 CHOLESTEROL IS THE PRECURSOR OF STERIOD HORMONES

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4 CONVERSION OF CHOLESTROL TO PREGNENOLONE

5 MINERALOCORTICOCOIDES

6 Progesteron 21-Hydroxylase 11-Deoxycorticosteron 11-Hydroxylase Corticosterone 18-Hydroxylase 18-Hydroxycorticosteron Aldosteron 18-Hydroxysteroid Dehydrgenase

7 FUNCTION Enhanced Reabsorption of Na + Enhanced K + Excretion Enhanced H + Excretion

8 REGULATION Renin - Angiotensin System Potassium Sympathic System

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10 HYPERALDOSTERONISM Primary Aldosterone producing adenoma (Conn s syndrome) Idiopathic adrenal hyperplasia Secondary Decreased renal perfusion

11 DIAGNOSIS OF HYPERALDOSTERONISM Increased urinary potassium excretion, despite of hypokalemia, and presence of hypertension

12 DIFFERENTIATION OF PRIMARY AND SECONDARY HYPERALDOSTERONISM Plasma Aldosterone (PA) Plasma Renin Activity (PRA) PA / PRA Ratio Primary Secondary Plasma Aldosterone (PA) High High Plasma Renin Activity (PRA) Low High PA / PRA Ratio > 25 < 25 Captopril Suppression Test 1 mg/kg (50 mg) captopril is given PA / PRA Ratio is determined before and 3h after

13 GLUCOCORTICOIDES

14 Progesteron 17-Hydroxylase 17-Hydroxy Progesteron 21-Hydroxylase 11-Deoxycortisol Cortisol 11-Hydroxylase

15 FUNCTION Increased Blood Glucose Increased Protein Catabolism Inhibition of Amino Acid Uptake Supression of Immune System

16 REGULATION By CRH and ACTH

17 HYPERCORTISOLISM (Cushing Syndrome) Primary Hypercortisolism Adenoma, Carcinoma, Nodular Hyperplasia Secondary Hypercortisolism Pituitary Adenoma (Cushing Disease) Nonpituitary neoplasm (Ectopic ACTH) Tertiarty Hpercortisolism Ectopic CRH Syndrome Exogenous Glucocorticoides Pseudo-Cushing s s syndrome Stress, Chronic disease, Obesity, Alcoholism,

18 LABORATORY DIAGNOSIS Screening Tests Confirmatory Tests Differential Diagnosis

19 Plasma or Serum Cortisol 80-90% is in bound form and 10-20% as free 70-80% to CBG and 10-20% to Alb Has severe fluctuation due to circadian and ultradian secretion Reference interval: 8-10 AM 5-23 ug/dl and 4-6 PM 3-13 ug/dl So, random or morning serum cortisol measuring is not useful for screening of Cushing syndrome

20 SCREENING TESTS Low-dose Overnight DST Urinary Free Cortisol Midnight Salivary Cortisol

21 SCREENING TESTS Low-Dose Overnight DST (Dexamethazone Stimulation Test) 1 mg dexamethazone at PM orally Blood collection for serum cortisol at 8-9 9AM Normal : < 5 ug/dl (Recently criteria : < 1.8 ug/dl) Has 30% FP, so positive results so needs confirmaton Drugs (phenobarbital, dilantin), Malabsorption, Estrogen, Pseudo- Cushing syndrome Has 2% FN, so suspicious cases needs other screening tests

22 SCREENING TESTS 24h Urinary Free Cortisol (UFC) 1-2% is excreted as free cortisol It is reflection of free cortisol in circulation which freely filtered by the glomerulus Urinary cortisol excretion is increased when plasma cortisol concentration exceeds mg/dl UFC also increases in pseudo-cushing, starvation, hydratation, and pregnancy Urinary cortisol excretion decreases by reduction in GFR Reference ranges are method-dependentdependent For HPLC : < 50 ug/24h

23 SCREENING TESTS Salivary Cortisol Its measuring is simple and noninvasive Has good correlation with plasma cortisol and also UFC Reference ranges are assay-dependent By RIA : < 0.15 ug/dl

24 CONFIRMATORY TESTS Midnight Plasma Cortisol 2 Day Low-Dose DST

25 CONFIRMATORY TESTS Plasma or Serum Cortisol Plasma cortisol decrease gradually throughout the day, reaching the nadir in the late evening between 11:00 PM and midnight Concentrations more than 7.5 mg/dl has a diagnostic sensitivity 90-96% 96% and specificity 100%

26 CONFIRMATORY TESTS 2 Day Low-Dose DST Collection of two baseline 24h urine for UFC 0.5 mg dexamethazone is given orally every 6h for the next 2 days Collection of 24h urine for UFC on day two Normal : < 10 ug/24h Diagnostic sensitivity : % Or blood for plasma cortisol after 48h Normal : < 1.8 ug/dl Diagnostic sensitivity and specificity : 95%

27 DIFFERENTIAL DIAGNOSIS 2 Day High-Dose DST High-Dose Overnight DST Plasma ACTH CRH Stimulation Test

28 DIFFERENTIAL TESTS 2 Day High-Dose DST Collection of one baseline 24h urine for UFC 2 mg dexamethazone is given orally every 6h for the next 2 days Collection of 24h urine for UFC during first and second day Cushing disease : > 50% reduction in FUC Adrenal and ectopic : < 50% reduction in FUC Diagnostic sensitivity and specificity : 60-85% Or blood for plasma cortisol before, during and after Cushing disease : > 50% reduction in basal plasma cortisol Adrenal and ectopic : < 50% reduction in basal plasma cortisol

29 DIFFERENTIAL TESTS High-Dose Overnight DST Collection of blood for plasma cortisol at 8:00 AM 8 mg dexamethazone is given orally at 11:00 PM Collection blood for plasma cortisol Cushing disease : < 5 ug/dl

30 DIFFERENTIAL TESTS Morning Plasma ACTH Collection of blood for plasma ACTH at 9:00 AM ACTH Independent : < 10 pg/ml ACTH Dependent : > 20 pg/ml Suspicious : pg/ml CRH Stimulation Test

31 CONFIRMATORY TESTS CRH Stimulation Test Collection of two basal blood 5 minutes apart for cortisol and ACTH Injection of 1ug/kg or 100 ug ocrh intravenously Blood is sampled every 15 minutes for 1 2 hours for cortisol, ACTH Normal : 15-20% increase in cortisol and ACTH Cushing disease : > 50% increase in ACTH ( >10 pg/ml) > 20% increase in cortisol ( > 25 ug/dl) Adrenal disease : Suppressed ACTH ( < 10 pg/ml) High cortisol ( > 25 ug/dl)

32 HYPOCORTISOLISM (Cushing Syndrome) Primary Hypocortisolism Secondary Hypocortisolism Tertiarty Hpocortisolism

33 PLASMA OR SERUM CORTISOL Plasma or Serum Cortisol 8-9 AM serum cortisol less than 3 ug/dl is diagnostic for adrenal insufficiency Stress during blood collection, increases cortosol; so normal value dose not rule out adrenal insufficiency Random serum cortisol above 20 ug/dl and value above 25 ug/dl during stress, rule out adrenal insufficiency

34 DIFFERENTIAL TESTS Plasma or Serum ACTH Blood collection for ACTH at 8-10 AM Primary : > pg/ml Central : < 10 pg/ml

35 DIFFERENTIAL TESTS Short ACTH Stimulation Test Collection of blood for plasma cortisol Fasting is not necessary 250 ug cortrosyn intravascular or intramuscullar Rare allergic reaction Blood collection after 30 to 60 min Normal : > ug/dl Adrenal insufficiecy : No change Central : > 70 ug/dl

36 DIFFERENTIAL TESTS Prolong ACTH Stimulation Test Collection of blood for plasma cortisol Injection of 250 ug cortrosyn osy for 3 sequential days Next, Blood collection for plasma cortisol Normal : increase to 2.5 times of base Adrenal insufficiency : no or little increase Central : severe increase

37 DIFFERENTIAL TESTS Overnight Metyrapon Test Metyrapon inhibits 11-hydroylase which results in elevation of 11-deoxycortisol and decrease in cortisol production 30 mg/kg is given at 11 o1 12 PM Collection of blood for plasma cortisol, 11-deoxycortisol and ACTH Cortisol 11-deoxycortisol ACTH Normal < 5 ug/dl > 70 ug/dl > 100 ng/l Adrenal insufficiency Low Increase Central insufficiency Low No Increase

38 DEFICIENCY Addison s s Disease Congenital Adrenal Hyperplasia Desmolase 3β OHSD & ISOMERASE 17-Hydroxylase 21-Hydroxylase 11-Hydroxylase

39 ADRENAL ANDROGENS

40 Progesteron 17-Hydroxylase 17-Hydroxy Progesteron DHEA DHEA-S Desmolase Sulfokinase

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