24-hour urine free cortisol

Pick Ordered or Not ordered to see the note.

Indicated when

• —One of three first-line tests for Cushing's syndrome (with late-night salivary cortisol or a 1 mg dexamethasone suppression test), used only in patients with multiple, progressive features compatible with the syndrome, particularly discriminating features (bruising, plethora, proximal myopathy, striae, features unusual for age), or an adrenal incidentaloma [1, 2]

Not indicated when

• —Screening for Cushing's syndrome in obesity or metabolic syndrome alone [1]
• —Investigating fatigue without discriminating features [3]
• —Routine 'adrenal' screening panels [4]

Why not

Even as a first-line test, 24-hour urine free cortisol needs at least two properly collected specimens because of day-to-day variability, can be falsely elevated by high fluid intake, and produces both false positives and false negatives, so a single abnormal result should not be treated as diagnostic without a second, concordant test [1].

Better first step

Confirm discriminating clinical features first; if present, pair 24-hour urine free cortisol with a second first-line test (late-night salivary cortisol or a 1 mg dexamethasone suppression test) rather than relying on either alone [1].

Typical ND rationale

An ND may order 24-hour urine free cortisol as a whole-day measure of cortisol output when investigating fatigue or suspected adrenal dysfunction, reasoning that it avoids the single-time-point limitation of a blood draw.

Ontario coverage & CONO orderability

OHIP status

unverified

The 2026 Schedule's only 'Cortisol' line item (L303) carries no specimen qualifier; this session's review of the Schedule text found no separate 24-hour urine cortisol line item, so it is unverified whether a community lab bills the urine methodology under L303 or offers it under OHIP at all. ND-ordered testing is patient-paid regardless [6, 7].

CONO orderable

Yes — CONO list #147, #148

CONO list items 147 ('Cortisol – bound and unbound, no differentiation,' urine) and 148 ('Cortisol / Cortisone,' urine).

Linked conditions

• Cushing's syndrome ↗
• "Adrenal fatigue" ↗

Counselling script

“Because you don't have the specific signs we look for with Cushing's syndrome — things like unusual bruising, stretch marks, or muscle weakness — a 24-hour urine cortisol isn't likely to give us useful information right now. If those signs show up, I'll order it, usually alongside a second test to be sure.”

Revisit if

• —New bruising, facial plethora, or wide violaceous striae
• —Proximal muscle weakness
• —Adrenal mass found incidentally on imaging

References

1. [1]Endocrine Society (2008). The Diagnosis of Cushing's Syndrome: An Endocrine Society Clinical Practice Guideline. linkolder guideline24-hour urine free cortisol is one of three first-line tests for Cushing's syndrome, only with discriminating features present; collection and interpretation caveats
2. [2]Pituitary Society (2021). Consensus on diagnosis and management of Cushing's disease: a guideline update. link2021 Pituitary Society consensus update on screening and diagnosis of Cushing's disease
3. [3]BMC Endocrine Disorders (2016). Adrenal fatigue does not exist: a systematic review. linkolder guidelineFatigue alone, without discriminating features, is not a validated indication for adrenal cortisol testing
4. [4]College of Family Physicians of Canada / Choosing Wisely Canada (2026). Family Medicine: Fifteen Tests and Treatments to Question. linkDon't do routine screening tests unless directly indicated by the patient's risk profile
5. [5]Ontario Ministry of Health (2026). Ontario Health Insurance Plan: Schedule of Benefits for Laboratory Services (effective April 1, 2026). linkCommunity lab tests are insured only when ordered under the Schedule by an authorized prescriber
6. [6]Government of Ontario (e-Laws) (2026). Health Insurance Act, R.R.O. 1990, Reg. 552: General, s. 22 (insured laboratory services). linkA lab test is insured only when ordered by a physician, midwife, or NP who has clinically assessed the patient
7. [7]Ontario Ministry of Health (2026). Ontario Health Insurance Plan: Schedule of Benefits for Laboratory Services (effective April 1, 2026). linkTests ordered by anyone other than an authorized provider, including NDs, are not insured services