Cortisol In Serum

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Contents 1 Reference-interval 2 Increases 3 Decreases 4 Methods 5 Interferences 6 Notes 7 More General Terms 8 References

Reference-interval

• 10-25 ug/ dL, 8 AM (normal AM cortisol)
• 5-12 ug/ dL, 10 PM

• diurnal variation; AM > PM cortisol
• serum level at 10 PM is generally 50% of that at 8 AM

• acute stress: 20-120 ug/ dL
• random cortisol of > 18-20 ug/ dL makes adrenal insufficiency unlikely

Increases

• hypoglycemia
• stress
• ether narcosis
• pregnancy
• obesity
• depression
• hyperthyroidism
• Cushing' syndrome

Decreases

• hypothyroidism
• cirrhosis
• hepatitis
• adrenal insufficiency

Methods

• Radioimmunoassay ( RIA)
• other competitive binding assays with fluorescent detection

Interferences

• in vivo

• agents that increase serum cortisol levels

• amphetamines, corticotropins, cortisone acetate, estrogens, ethanol, hydrocortisone, interferon gamma, methoxamine, metoclopramide, naloxone, nicotine, oral contraceptives, vasopressin

• agents that decreased serum cortisol levels

• aminoglutethimide, beclomethasone, betamethosone, danazol, desoximetasone, dexamethasone, etomidate, ketoconazole, levodopa, lithium carbonate, methylprednisolone (depot), metyrapone, morphine, phenytoin (women), trilostane

• chemical interferences

• RIA: estrogen, prednisolone, prednisone
• fluorescence: mepacrine, quinacrine, spironolactone
• other increases [3]: chlordiazepoxide, dexamethsone, digoxin, methenamine, thorazine

Notes

• serum levels are influenced by clearance rates, thus serum levels may be normal when cortisol secretion is increased or decreased

• * Most serum cortisol is bound to corticosteroid-binding globulin & albumin. Thus free cortisol is the physiologically active form. Diminished total, but not free cortisol may be a result of diminished serum albumin. [4]
• Cortisol secretion is not influenced by age.

More General Terms

• special chemistry test

References

1. Guide to Clinical Laboratory Tests, 3rd ed, NW Teitz (ed) WB Saunders, 1995
2. Medical Knowledge Self Assessment Program (MKSAP) 11, American College of Physicians, Philadelphia 1998
3. Clinical Diagnosis & Management by Laboratory Methods, 19th edition, J.B. Henry (ed), W.B. Saunders Co., Philadelphia, PA. 1996, pg 10
4. Journal Watch 24(10):77, 2004 Hamrahian AH, Oseni TS, Arafah BM. Measurements of serum free cortisol in critically ill patients. N Engl J Med. 2004 Apr 15;350(16):1629-38. PMID: [1]

cortisol in serum