Cortisol
About Test
The Cortisol test measures the level of cortisol, a hormone produced by the adrenal glands, in the blood. Cortisol is crucial for regulating various bodily functions, including metabolism, immune response, and the body's stress response. It is often referred to as the "stress hormone" because its levels typically rise in response to stress and help the body manage and recover from stressful situations.
This test is commonly used to diagnose and monitor conditions related to abnormal cortisol production, such as Cushing's syndrome, characterised by excessive cortisol levels, and Addison's disease, associated with insufficient cortisol production. Cortisol levels follow a daily rhythm, typically peaking in the morning and declining throughout the day, so the timing of the test can be important for accurate diagnosis.
Monitoring cortisol levels helps healthcare providers assess adrenal function, guide treatment for adrenal or hormonal disorders, and manage conditions linked to hormonal imbalances, ensuring effective and personalised patient care.
Sample Requirements
Gold SST Tube
Stability
Serum: 24 hours at 20-25 °C, 4 days at 2-8 °C,
12 months at -20 °C (± 5°C).
Turnaround Time
4 hours
Assay Interferences
Recovery within ± 10 %
Bilirubin: ≤ 428 μmol/L or ≤ 25 mg/dL
Hemoglobin: Hb ≤ 0.311 mmol/L or ≤ 0.5 g/dL
Intralipid: ≤ 1500 mg/dL
Biotin: ≤ 123 nmol/L or ≤ 30 ng/mL
Rheumatoid Factors: No interference was observed from rheumatoid factors up to a concentration of 600 IU/mL
Others: IgG ≤ 50 g/L, IgA ≤ 10 g/L and IgM ≤ 10 g/L
Reference Range (nmol/L):
9:00 AM cortisol
Suggests adrenal insufficiency: <100
Unlikely adrenal insufficiency: >450
Consider a short synacthen test: 100 - 400
Midnight cortisol Excludes endogenous Cushing's:
<50
Critical Value:
Not applicable