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Test ID: CINP Cortisol, Mass Spectrometry, Serum

Reporting Name

Cortisol, S, LC-MS/MS

Useful For

Second-order testing when cortisol measurement by immunoassay (eg, CORT / Cortisol, Serum) gives results that are not consistent with clinical symptoms, or if patients are known to, or suspected of, taking exogenous synthetic steroids. For confirming the presence of synthetic steroids, order SGSS / Synthetic Glucocorticoid Screen, Serum.


An adjunct in the differential diagnosis of primary and secondary adrenal insufficiency


An adjunct in the differential diagnosis of Cushing syndrome


This test is not recommended for evaluating response to metyrapone; DOC / 11-Deoxycortisol, Serum is more reliable.

Clinical Information

Cortisol, the main glucocorticoid (representing 75%-95% of the plasma corticoids), plays a critical role in glucose metabolism and in the body's response to stress. Both hypercortisolism and hypocortisolism can cause disease.


Cortisol levels are regulated by adrenocorticotropic hormone (ACTH), which is synthesized by the pituitary in response to corticotropin releasing hormone (CRH). CRH is released in a cyclic fashion by the hypothalamus, resulting in diurnal peaks (6-8 a.m.) and troughs (11 p.m.) in plasma ACTH and cortisol levels.


The majority of cortisol circulates bound to corticosteroid-binding globulin and albumin. Normally, less than 5% of circulating cortisol is free (unbound). Free cortisol is the physiologically active form and is filterable by the renal glomerulus.


Pathological hypercortisolism due to endogenous or exogenous glucocorticoids is termed Cushing syndrome. Signs and symptoms of pathological hypercortisolism may include central obesity, hypertension, hyperglycemia, hirsutism, muscle weakness, and osteoporosis. However, these symptoms and signs are not specific for pathological hypercortisolism. The majority of individuals with some or all of the symptoms and signs will not suffer from Cushing syndrome.


When Cushing syndrome is present, the most common cause is iatrogenic, due to repeated or prolonged administration of, mostly, synthetic corticosteroids. Spontaneous Cushing syndrome is less common and results from either primary adrenal disease (adenoma, carcinoma, or nodular hyperplasia) or an excess of ACTH (from a pituitary tumor or an ectopic source). ACTH-dependent Cushing syndrome due to a pituitary corticotroph adenoma is the most frequently diagnosed subtype; most commonly seen in women in the third through fifth decades of life. The onset is insidious and usually occurs 2 to 5 years before a clinical diagnosis is made.


Hypocortisolism most commonly presents with nonspecific lassitude, weakness, hypotension, and weight loss. Depending on the cause, hyperpigmentation may be present. More advanced cases and patients submitted to physical stress (ie, infection, spontaneous or surgical trauma) also may present with abdominal pain, hyponatremia, hyperkalemia, hypoglycemia, and in extreme cases, cardiovascular shock and renal failure.


The more common causes of hypocortisolism are:


Primary adrenal insufficiency:

-Addison disease

-Congenital adrenal hyperplasia, defects in enzymes involved in cortisol synthesis


Secondary adrenal insufficiency:

-Prior, prolonged corticosteroid therapy

-Pituitary insufficiency

-Hypothalamic insufficiency


See Steroid Pathways in Special Instructions.


In primary adrenal insufficiency, adrenocorticotropic hormone (ACTH) levels are increased, and cortisol levels are decreased; in secondary adrenal insufficiency both ACTH and cortisol levels are decreased.


When symptoms of glucocorticoid deficiency are present and the 8 a.m. plasma cortisol value is <10 mcg/dL (or the 24-hour urinary free cortisol value is <50 mcg/24 hours), further studies are needed to establish the diagnosis. The 3 most frequently used tests are the ACTH (cosyntropin) stimulation test, the metyrapone test, and insulin-induced hypoglycemia test. First, the basal plasma ACTH concentration should be measured, and the short cosyntropin stimulation test performed.


Cushing syndrome is characterized by increased serum cortisol levels. However, the 24-hour urinary free cortisol excretion is the preferred screening test for Cushing syndrome, specifically CORTU / Cortisol, Free, 24 Hour, Urine that utilizes liquid chromatography-tandem mass spectrometry. A normal result makes the diagnosis unlikely.


Symptoms or signs of Cushing syndrome in a patient with low serum and urine cortisol levels suggest possible exogenous synthetic steroid effects.

Testing Algorithm

See Steroid Pathways in Special Instructions.

Special Instructions

Report Available

2 to 5 days

Day(s) Performed

Monday through Friday

Clinical Reference

1. Lin CL, Wu TJ, Machacek DA, Jiang NS, Kao PC: Urinary free cortisol and cortisone determined by high-performance liquid chromatography in the diagnosis of Cushing's syndrome. J Clin Endocrinol Metab. 1997;82:151-155. doi: 10.1210/jcem.82.1.3687. 

2. Findling JW, Raff H: Diagnosis and differential diagnosis of Cushing's syndrome. Endocrinol Metab Clin North Am. 2001;30(3):729-747. doi: 10.1016/s0889-8529(05)70209-7.

3. Buchman Al: Side effects of corticosteroid therapy. J Clin Gastroenterol. 2001;33(4):289-297. doi: 10.1097/00004836-200110000-00006.

4. Dodds HM, Taylor PJ, Cannell GR, Pond SM: A high-performance liquid chromatography-electrospray-tandem mass spectrometry analysis of cortisol and metabolites in placental perfusate. Anal Biochem. 1997;247:342-347. doi: 10.1006/abio.1997.2074.

Method Name

Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)

Specimen Type

Serum Red

Ordering Guidance

The preferred screening test for Cushing syndrome is the 24-hour urinary free cortisol excretion, order CORTU / Cortisol, Free, 24 Hour, Urine.


When patients are not taking, or are not suspected to be taking, exogenous glucocorticoids, order CORT / Cortisol, Serum.

Specimen Required

Collection Container/Tube: Red top (serum gel/SST are not acceptable)

Specimen Volume: 0.6 mL

Submission Container/Tube: Plastic vial

Collection Instructions:

1. Morning (8 a.m.) and afternoon (4 p.m.) specimens are preferred.

2. Include time of collection.

3. Centrifuge and aliquot serum into a plastic vial.

Additional Information: If multiple specimens are collected, send a separate order for each specimen.

Specimen Minimum Volume

0.25 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Red Refrigerated (preferred) 28 days
  Ambient  28 days
  Frozen  28 days

Reference Values

5-25 mcg/dL (a.m.)

2-14 mcg/dL (p.m.)

Pediatric reference ranges are the same as adults, as confirmed by peer-reviewed literature. 


Petersen KE: ACTH in normal children and children with pituitary and adrenal diseases. I. Measurement in plasma by radioimmunoassay-basal values. Acta Paediatr Scand. 1981;70:341-345

Test Classification

This test was developed, and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
CINP Cortisol, S, LC-MS/MS 87429-7


Result ID Test Result Name Result LOINC Value
84279 Cortisol, S, LC-MS/MS 2143-6
23606 AM Cortisol 9813-7
23607 PM Cortisol 9812-9
Mayo Clinic Laboratories | Endocrinology Catalog Additional Information: