Pathology tests database

Sample and container requirements

Plain 24 hr Urine

Minimum volume required

500 µL urine

Special requirements

The volume, dates & times of collection should be noted.

Patient preparation

Samples from patients receiving high biotin doses (i.e. >5 mg/day) should be taken at least 8 hours post-dose. Pregnancy, contraceptives and oestrogen therapy give rise to elevated cortisol concentrations. Samples from patients treated with prednisolone, methyl-prednisolone or prednisone may give falsely elevated concentrations of cortisol.

Sample viability

Turnaround time

14 days

Reference range

<130 nmol/24hr (Source: locally derived)

Clinical guidance

Please refer to LabTestsOnlineUK to learn more about cortisol. https://labtestsonline.org.uk/tests/cortisol-test

Notes

Due to problems with incomplete urinary collections and the false positives in UFC which occur in obesity and stressful illness, many clinicians may prefer an overnight or low dose dexamethasone suppression test to UFC measurement.