Imperial Collage Healthcare

Cortisol (blood)


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 Required
Serum (red top) or SST (gold top)


Sample Volume
0.5 mL


Turnaround Time
1 day


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