Imperial Collage Healthcare

Cortisol (urine)

Test Background
Cortisol is secreted in a diurnal pattern with peak values occurring in the early morning. Random serum cortisol may be difficult to interpret. The diurnal rhythm may be disrupted or lost in Cushing’s syndrome. Free cortisol measured in a 24 hour urine collection may be a more useful diagnostic tool in some patients.

Clinical Indications
Most specific diagnostic indicator of Cushing’s syndrome Differential diagnosis of phaeochromocytoma and Conn’s syndrome

Reference Range
50-270 nmol/L

Sample Required
24 hour urine collection

Sample Collection
Please include time and volume for the 24 hour collection.

Sample Volume
1 mL


Stable at 2-8oC for 24 hours. Please freeze pending dispatch for analysis.

Can be sent by first class post.

Turnaround Time
2 weeks

Acidified samples are unsuitable for this assay.

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