What is the reference range for Late-Evening Cortisol (23:00)?

The standard reference range for Late-Evening Cortisol (23:00) is Late evening (23:00): typically <50 nmol/L (<1.8 µg/dL); the nadir of the circadian rhythm.. Reference ranges vary by laboratory and assay platform — interpret in context of the issuing laboratory's stated range.

Which tests measure Late-Evening Cortisol (23:00)?

Late-Evening Cortisol (23:00) is measured in 1 test on BiomarkersLabs.com, including Cortisol, 4 Specimens.

Biomarker Reference · Cortisol Late

What does the Late-Evening Cortisol (23:00) test measure?

Q: What is Late-Evening Cortisol (23:00)?

Late-evening cortisol marks the circadian nadir, coinciding with the onset of melatonin secretion and peak sleep propensity. At this point cortisol output is maximally suppressed, and even mild elevations lose the overlap with physiological stress seen during daytime sampling.

Q: Why is Late-Evening Cortisol (23:00) measured?

Loss of the evening nadir — late-night cortisol persistently above 140 nmol/L (5 µg/dL) or, depending on the assay, >50 nmol/L — is one of the most specific screening findings for Cushing syndrome. It detects autonomous secretion that escapes normal circadian suppression.

Q: Which tests measure Late-Evening Cortisol (23:00)?

Late-Evening Cortisol (23:00) is measured in 1 test on BiomarkersLabs.com, including Cortisol, 4 Specimens.

Late-Evening Cortisol (23:00) (Cortisol Late) is a clinical biomarker used in adrenal-stress assessment. Late-evening cortisol marks the circadian nadir, coinciding with the onset of melatonin secretion and peak sleep propensity. It is measured in 1 laboratory test on BiomarkersLabs.com.

Reference Range: Late evening (23:00): typically <50 nmol/L (<1.8 µg/dL); the nadir of the circadian rhythm.
Units: nmol/L, µg/dL
Measured In: 1 test
Category: Adrenal

Functional medicine optimalLate-evening cortisol should reach a clear nadir, typically below 50 nmol/L; higher values suggest loss of circadian rhythm or cortisol excess.

What is Late-Evening Cortisol (23:00)?

Late-evening cortisol marks the circadian nadir, coinciding with the onset of melatonin secretion and peak sleep propensity. At this point cortisol output is maximally suppressed, and even mild elevations lose the overlap with physiological stress seen during daytime sampling.

Why is Late-Evening Cortisol (23:00) measured?

Loss of the evening nadir — late-night cortisol persistently above 140 nmol/L (5 µg/dL) or, depending on the assay, >50 nmol/L — is one of the most specific screening findings for Cushing syndrome. It detects autonomous secretion that escapes normal circadian suppression.

Reference ranges

Standard reference: Late evening (23:00): typically <50 nmol/L (<1.8 µg/dL); the nadir of the circadian rhythm.
Functional medicine optimal: Late-evening cortisol should reach a clear nadir, typically below 50 nmol/L; higher values suggest loss of circadian rhythm or cortisol excess.
Units: nmol/L, µg/dL

Reference ranges vary by laboratory and assay platform. Interpret in context of the issuing laboratory's stated range.

Tests that measure Late-Evening Cortisol (23:00)

1 test on BiomarkersLabs.com include this biomarker.

BML-ADR-031Comprehensive

Cortisol, 4 Specimens

Late-Evening Cortisol (23:00) reference range in this test: Late evening (23:00): typically <50 nmol/L (<1.8 µg/dL); the nadir of the circadian rhythm.

Related clinical conditions

Related Biomarkers

Frequently measured alongside

Cortisol (morning, ~30 minutes post-waking)Cortisol-AM5 tests Cortisol (midday)Cortisol-MD4 tests Cortisol (afternoon specimen)Cortisol PM4 tests Diurnal Cortisol Slope (Derived)Cortisol Slope3 tests

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