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9 AM Cortisol

Morning Cortisol Basal Cortisol 9am Serum Cortisol
Serum (SST; must be taken 08:00–09:00) nmol/L

About this test

Diurnal peak of cortisol secretion occurs at 8–9 AM. Used as a screening test for adrenal insufficiency; a result >450 nmol/L essentially excludes Addison's disease.

Reference Ranges

Sex Age Range Notes
All ≥ 18 yrs 171 – 536 Adult 9 AM (varies by assay; >450 excludes adrenal insufficiency; <100 is diagnostic of insufficiency)

Clinical Interpretation

Low / Decreased
Low (<100 nmol/L) — adrenal insufficiency likely; proceed to Short Synacthen Test. Grey zone 100–450 — SST indicated.
High / Increased
Elevated — Cushing's syndrome (poorly helpful in isolation; 24h UFC or overnight DST preferred).

Related Tests

ACTH
Specimen
Serum (SST; must be taken 08:00–09:00)
Reporting Unit
nmol/L
Category
⚗️ Endocrinology

⚠ Clinical Note
Reference ranges are indicative. Always interpret results in the context of the individual patient and local laboratory reference intervals, which may vary.