Cortisol Studies: Blood, Saliva, Urine


Hydrocortisone, compound F.

To assist in diagnosing adrenocortical insufficiency such as found in Cushing syndrome and Addison disease.

Patient Preparation
Single cortisol level There are no food, fluid, activity, or medication restrictions unless by medical direction. Cortisol peak specimens should be collected between 0600 and 0800 hr; trough specimens should be collected between 2300 and 2400 hr.

Other Cortisol Studies Used in the Diagnosis of Cushing Syndrome
Specimen type/StudyGeneral Instructions
Salivary cortisol
  • Restrict alcohol for 12 hr prior to specimen collection.
  • Restrict food and fluids for 15 min prior to sample collection.
  • Do not collect immediately after any activity that may cause gums to bleed (e.g., brushing, flossing, etc.).
  • Collect sample between 2300 and 2400.
  • Per instructions, place sample in properly labelled saliva collection kit (patient name, date of birth, collection date, collection time).
24 hr urine free-cortisolUrine is collected over a timed (24 hr) interval and stored in a clean plastic container with 10g boric acid as a preservative

Cortisol and adrenocorticotropin hormone (ACTH) studies are often ordered together. In order not to duplicate large amounts of information please refer to the study titled “Adrenocorticotropin Hormone (and Challenge Tests)” for additional detailed information regarding ACTH and cortisol challenge testing.Normal Findings
Method: Electrochemiluminescent immunoassay.

TimeConventional UnitsSI Units (Conventional Units × 27.6)
Birth–1 wk2–11 mcg/dL55–304 nmol/L
1 wk–adult/older adult5–25 mcg/dL138–690 nmol/L
1 wk–adult/older adult3–16 mcg/dL83–442 nmol/L
Long-term use of corticosteroids in patients, especially older adults, may be reflected by elevated cortisol levels (Cushing syndrome). Abrupt cessation of corticosteroids may be reflected in decreased cortisol levels since the body’s normal production of cortisol has been suppressed. Adrenal insufficiency may occur in this case and could be life threatening. Cessation of corticosteroid therapy must always be tapered. After the first week of life, cortisol levels approach adult levels.

Other Cortisol Studies Used in the Diagnosis of Cushing Syndrome
Salivary CortisolConventional UnitsSI Units (Conventional Units × 27.6)
0700–0900100–750 ng/dL2760–20,700 nmol/L
1500–1700Less than 401 ng/dLLess than 11,068 nmol/L
2300–midnightLess than 100 ng/dLLess than 2760 nmol/L
24 hr Urine Free CortisolConventional UnitsSI Units (Conventional Units × 27.6)
  3–8 yr1.4–20 mcg/24 hr38.6–552 nmol/L
  9–12 yr2.6–37 mcg/24 hr71.8–1021 nmol/L
  13–17 yr4–56 mcg/24 hr110.4–1545.6 nmol/L
  18 yr–adult3.5–45 mcg/24 hr96.6–1242 nmol/L

Critical Findings and Potential Interventions

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