Cortisol, Serum (Morning Sample)

Normal cortisol levels in the blood:

·         6 to 8 a.m.: 10 to 20 µg/dL

·         Around 4 p.m.: 3 to 10 µg/dL

·         Around 12 a.m.: Less than 5 µg/dL

Normal cortisol levels may vary among individuals. Increased or decreased cortisol levels can be assessed only if the cortisol level in blood does not follow the diurnal pattern as it should.

Cortisol levels may fall outside the normal range for the time of day due to diseases or due to lifestyle factors such as irregular sleeping times.

Reference range may vary from lab to lab*

Causes of increased cortisol levels:

·    Long-term treatment with glucocorticosteroid hormones like prednisone, dexamethasone, etc.

·       Pituitary tumors that increase ACTH production

·       ACTH-producing tumors in other parts of the body

·       Adrenal tumors that increase cortisol secretion

·      Congenital Adrenal Hyperplasia, a disease which causes excessive growth of adrenal gland cells

·    Recent surgery, illness, injury, or sepsis

·        CRH-producing tumors in rare cases

Causes of decreased cortisol levels:

·         Reduced cortisol production due to damage or diseases of the adrenal gland (primary adrenal insufficiency) like Addison’s disease

·         Reduced ACTH production due to reduced activity of the pituitary gland or pituitary tumors (secondary adrenal insufficiency)