Lack of diurnal rhythm of low molecular weight insulin-like growth factor binding protein in patients with Cushing's disease.
A specific radioimmunoassay with antibodies raised against the 25 kD insulin-like growth factor binding protein (25 kD IGFBP) in amniotic fluid was used to measure levels of cross-reacting protein in human serum and plasma. Plasma samples collected continually at 20-min intervals during 24-h in 6 healthy adults revealed a distinct diurnal rhythm in the concentration of 25 kD IGFBP. The lowest levels (9-13 micrograms/l) were found between 13.00 and 24.00 h with a rise after midnight to maximum levels (23-71 micrograms/l) between 03.00 and 09.00 h. There was no relation between the patterns of GH and 25 kD IGFBP. In 3 patients with active Cushing's disease, the levels of 25 kD IGFBP in plasma samples collected during 12 h, 19.00-07.00 h, were generally low and without nocturnal variations. One of the patients studied after extirpation of a pituitary adenoma displayed a nocturnal rhythm with maximum levels of 25 kD IGFBP between 03.00 and 07.00 h. Eight patients treated with stereotactic pituitary irradiation owing to Cushing's disease also showed a distinct nocturnal increase of 25 kD IGFBP. The results indicate the existence of a diurnal rhythm of 25 kD IGFBP in adults. Further, low levels and lack of diurnal rhythm of 25 kD IGFBP are demonstrated in Cushing's disease.
Degerblad
M
M
Department of Endocrinology, Karolinska Hospital, Stockholm, Sweden.
Póvoa
G
G
Thorén
M
M
Wivall
I L
IL
Hall
K
K
D000328:Adult; D001786:Blood Glucose / Q000032:analysis; D002096:C-Peptide / Q000097:blood; D002352:Carrier Proteins / Q000097:blood*; D002940:Circadian Rhythm; D003480:Cushing Syndrome / Q000097:blood*; D005260:Female; D013006:Growth Hormone / Q000097:blood; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D018969:Insulin-Like Growth Factor Binding Proteins; D008297:Male; D008970:Molecular Weight
D001786:Blood Glucose; D002096:C-Peptide; D002352:Carrier Proteins; D018969:Insulin-Like Growth Factor Binding Proteins; D013006:Growth Hormone; D006854:Hydrocortisone