Unstimulated:
Premature:
Premature 26-28w 3.2 - 39.7 nmol/L
Premature 29-36w 2.0 - 13.1 nmol/L
Term neonate:
Day 3-8
0.7- 34.6 nmol/L
Day 13-15 0.70 - 3.6 nmol/L
Day 16-29 0.5 - 4.7 nmol/L
Full term (1-5mo) 0.3 - 5.8 nmol/L
6-11m 0.3 - 8.0 nmol/L
1-3 years 0.2 -7.1 nmol/L
4-6 years 0.2 - 8.4 nmol/L
>6 years Male <3 nmol/L (Frederiksen, Kunz)
Female <2.2 nmol/L
Uncertainty of measurement: 20% at 2 nmol/L, 10% at >10 nmol/L
Overnight metyrapone stimulation test (30mg/kg orally, max 3g) taken at 2300-2400hr.
If 0800-0900hr plasma cortisol the next morning is <200nmol/L, metyrapone inhibition of cortisol synthesis and subsequent ACTH stimulation has been adequate.
11-deoxycortisol >200 nmol/L -normal (adequate hypothalamic/pituitary response)
<200 nmol/L -secondary adrenal insufficiency
Liquid chromatography mass spectrometry (LCMS)
Measurement of 11-deoxycortisol is mostly performed in one of two clinical settings:
Congenital Adrenal Hyperplasia: 11-deoxycortisol is raised in 11-hydroxylase deficiency, an uncommon inherited enzyme defect in steroidogenesis. This enzyme is the final enzymatic step in the synthesis of cortisol. In affected patients the lack of cortisol feedback stimulation of pituitary ACTH secretion leads to increased ACTH stimulation of steroidogenesis, with increased levels of 11-deoxycortisol, the final intermediate before the block. Levels of 11-deoxycortisol are not raised in patients with the most common form of congenital adrenal hyperplasia, 21-hydroxylase deficiency (which affects the step before 11-hydroxylase).
Metyrapone test: This test is used in the evaluation of suspected insufficiency of the hypothalamic-pituitary-adrenal axis. However, it does not clearly distinguish between primary/secondary causes in possible combined deficiency, and carries the rare potential risk of precipitating adrenal crisis in primary adrenal insufficiency. This test should only be requested by an Endocrinologist. See related information under metyrapone test entry.
Following the administration of metyrapone (30mg/kg at 11PM), 11-deoxycortisol normally increases the next morning. A normal response is a rise in 11-deoxycortisol to at least 200nmol/L, with a fall in cortisol to <200nmol/L indicating adequate enzyme block. Failure of the 11-deoxycortisol to rise to >200nmol/L indicates secondary adrenal insufficiency (assuming the cortisol is <100nmol/L).
Measurement may also uncommonly be performed to test the degree of chronic enzyme block in patients with adrenal tumours on long-term metyrapone treatment to block the production of excess cortisol (as medical therapy for Cushing's syndrome).
The method does not cross-react with 11-deoxycorticosterone, which is converted to corticosterone in the mineralocorticoid pathway leading to the synthesis of aldosterone. This pathway may also be stimulated with an enzyme deficiency or block of 11-hydroxylase. It also does not cross-react with corticosterone or 21-deoxycortisol, other closely related metabolites in steroid synthesis pathways.
The chemical pathology team can be reached via email: chemicalpathologist@adhb.govt.nz or via Lablink (09) 307 4949 ext 22000 or 09-3078995
Emails will receive priority attention from the on-call chemical pathologist. Include the patients NHI.
After-hours: contact Lablink (Auckland City Hospital ext. 22000 or 09-3078995) or hospital operator for on duty staff after hours .
- Dr Samarina Musaad (Clinical Lead) : SamarinaM@adhb.govt.nz ext. 22402
- Dr Cam Kyle : CampbellK@adhb.govt.nz ext 22052
- Dr Weldon Chiu : WeldonC@adhb.govt.nz ext. 23427
- Dr Campbell Heron : CHeron@adhb.govt.nz ext. 23427
- Dr Sakunthala Jayasinghe Saku.Jayasinghe@adhb.govt.nz
- Dr Owen Yi WenyiYi@adhb.govt.nz
| Sample |
Serum - Plain EDTA Plasma (SST and Heparin tubes are NOT suitable) |
| Sample Preparation |
Centrifuge and aliquot - 500uL Freeze |
| Sample Stability |
Room temperature up to 24 hours Refrigerated up to 4 days Freeze if more than 4 days |
| Transport to LabPlus |
Send refrigerated up to 4 days Send frozen if more than 4 days |