Cortisol (blood)
| Category | Biochemistry >> Endocrinology |
|---|---|
| Test background |
Cortisol is the major glucocorticoid. Synthesis and secretion are stimulated by ACTH and are subject to a diurnal rhythm, with peak values occurring in the early morning. Excess cortisol occurs in Cushing’s syndrome; causes include: hypersecretion of ACTH, adrenal hyperplasia or neoplasia, and exogenous corticosteroid administration. Common causes of decreased cortisol synthesis include CAH, autoimmune and iatrogenic-mediated adrenal destruction, amyloidosis, hypopituitarism and occasionally sepsis. Dynamic function tests, eg. synacthen stimulation tests or dexamethasone suppression tests, may be used in the differential diagnosis of hypo- and hyper-secretion respectively. |
| Clinical Indications |
Inadequate cortisol levels/Addison’s disease: weight loss, muscle weakness, fatigue, low blood pressure or abdominal pain. Stress can induce an adrenal crisis that requires immediate medical attention (Addisonian crisis) Cushing’s syndromes: hypertension, hyperglycaemia, obesity, fragile skin, hyperpigmentation, muscle weakness and osteoporosis Presentation of irregular menses (women) or delayed development/short stature (children) |
| Reference range | 9am: 160-550 nmol/L |
| Sample & container required | Serum (red top) or SST (gold top) |
| Sample volume | 0.5 mL |
| Turnaround time | 1 day |