Insulin-like growth factor (IGF) I and II and IGF binding protein (IGFBP) 1, 2 and 3 in serum from patients with Cushing's syndrome.
In the present study of twenty-two patients with Cushing's syndrome, serum insulin-like growth factor (IGF)-I concentrations were normal to high with an increased mean IGF-I concentration, 40% above that of healthy subjects of the same age (p < 0.001). Serum IGF-II concentrations were normal. The morning serum IGF binding protein (IGFBP)-1 concentrations were within the range of healthy controls. IGFBP-1 was inversely correlated to the IGF-I concentration (p < 0.001) and to the 24 h urinary cortisol excretion (p < 0.005) with a combined R squared value of 0.58. In contrast to IGFBP-1, serum IGFBP-2 and IGFBP-3 concentrations were elevated by 1.89 +/- 1.78 SD and 0.92 +/- 0.78 SD (mean +/- 2 SD), respectively. Although increased, the serum IGFBP-2 concentration was inversely correlated to the IGF-I concentration (r = -0.67, p < 0.001). Immunoreactive IGFBP-3 was increased in proportion to IGF-I and the molar ratio [IGFBP-3]:[IGF-I] + [IGF-II] was close to unity (1.04 +/- 0.14), as that of healthy subjects. In serum from patients with Cushing's syndrome, with increased immunoreactive IGFBP-3, there was a corresponding increase in intact glycosylated 40-43 kDa IGFBP-3 as determined by Western ligand blotting. Neutral size chromatography of serum from patients with Cushing's syndrome showed that IGF-I and IGFBP-3 immunoreactivity were predominantly found at the elution volume of the ternary 150 kDa IGF-I/IGFBP-3/acid labile subunit complex and a similar pattern was displayed by normal serum.(ABSTRACT TRUNCATED AT 250 WORDS)
Bang
P
P
Department of Endocrinology, Karolinska Hospital, Stockholm, Sweden.
Degerblad
M
M
Thorén
M
M
Schwander
J
J
Blum
W
W
Hall
K
K
D000328:Adult; D000368:Aged; D015153:Blotting, Western; D002096:C-Peptide / Q000097:blood; D002352:Carrier Proteins / Q000097:blood / Q000737:chemistry; D002850:Chromatography, Gel; D003480:Cushing Syndrome / Q000097:blood*; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000652:urine; D018970:Insulin-Like Growth Factor Binding Protein 1; D018971:Insulin-Like Growth Factor Binding Protein 2; D018969:Insulin-Like Growth Factor Binding Proteins; D007334:Insulin-Like Growth Factor I / Q000032:analysis* / Q000737:chemistry; D007335:Insulin-Like Growth Factor II / Q000032:analysis* / Q000737:chemistry; D008297:Male; D008875:Middle Aged; D008970:Molecular Weight; D011863:Radioimmunoassay; D012044:Regression Analysis; D013002:Somatomedins / Q000032:analysis* / Q000737:chemistry
D002096:C-Peptide; D002352:Carrier Proteins; D018970:Insulin-Like Growth Factor Binding Protein 1; D018971:Insulin-Like Growth Factor Binding Protein 2; D018969:Insulin-Like Growth Factor Binding Proteins; D013002:Somatomedins; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D006854:Hydrocortisone