title: Circadian rhythm of serum cortisol in Cushing's disease.
abstract: Two women with typical clinical and biochemical features of pituitary-dependent Cushing's disease each underwent hourly blood sampling for 24 h on two separate occasions for measurement of serum cortisol. The 24-h mean serum cortisol concentrations (17.7 and 15.4 micrograms/dl in patient 1; 19.0 and 15.8 micrograms/dl in patient 2) were elevated (normal level, less than 12.5 micrograms/dl), as expected. Cosinor analysis of the patients' serum cortisol patterns revealed statistically significant circadian rhythms on all four profiles. The amplitude of the rhythm on both occasions in patient 1 (5.8 and 6.6 micrograms/dl) and on one of two occasions in patient 2 (7.2 and 10.5 micrograms/dl) fell in the range for the amplitude of the cortisol circadian rhythm in normal subjects (2.2-8.6 micrograms/dl). In contrast to commonly held belief, some patients with Cushing's disease may exhibit circadian variation of serum cortisol.
mesh_terms: D000328:Adult; D002940:Circadian Rhythm; D003480:Cushing Syndrome / Q000097:blood* / Q000652:urine; D003907:Dexamethasone; D005260:Female; D005938:Glucocorticoids / Q000652:urine; D006801:Humans; D006854:Hydrocortisone / Q000097:blood*
chemical_list: D005938:Glucocorticoids; D003907:Dexamethasone; D006854:Hydrocortisone