IGFBP-3 is a poor parameter for assessment of clinical activity in acromegaly.
OBJECTIVE
Elevated serum IGF-I and IGF binding protein-3 (IGFBP-3) levels have been found in patients with active acromegaly. We have studied the relative diagnostic merits of measurements of IGFBP-3 compared with IGF-I as a parameter of disease activity in these patients.


METHODS
Thirty untreated patients with acromegaly were compared with 30 healthy adults.


METHODS
Twenty-four-hour sampling for serum GH in patients with acromegaly, serum IGF-I and IGFBP-3.


RESULTS
Mean IGF-I levels were 22.0 nmol/l (range 6.5-38.4) in the healthy adults and 118.7 nmol/l (range 67.7-206.0) in patients with acromegaly. Mean IGFBP-3 levels were 3.5 mg/l (range 2.1-4.8) in controls and 5.4 mg/l (range 4.2-6.6) in patients with acromegaly. Mean IGF-I/IGFBP-3 ratios were 6.5 nmol/mg (range 1.9-14.5) in the healthy adults and 22.0 nmol/mg (range 14.3-32.7) in patients with acromegaly. There was a considerable overlap for IGFBP-3 levels but not for IGF-I levels, between normals and acromegalics. The IGF-I/IGFBP-3 ratio also showed overlap between normals and acromegalics. There was a significant correlation between the mean 24-hour GH and IGFBP-3 levels (P = 0.036) and between the IGF-I and IGFBP-3 levels (P < 0.002) in acromegaly. In patients with acromegaly, the IGFBP-3 levels showed a decrement, but the IGF-I/IGFBP-3 ratio did not change significantly with age.


CONCLUSIONS
IGFBP-2 has no additional discriminatory value over IGF-1 measurements for the assessment of clinical activity in acromegaly. In acromegaly, IGFBP-3 decreases with increasing age. In acromegaly, IGFBP-3 levels significantly correlate with mean 24-hour GH levels and IGF-I levels.
de Herder
W W
WW
Department of Internal Medicine III, University Hospital, Rotterdam, The Netherlands.
van der Lely
A J
AJ
Janssen
J A
JA
Uitterlinden
P
P
Hofland
L J
LJ
Lamberts
S W
SW
D000172:Acromegaly / Q000097:blood*; D000328:Adult; D000367:Age Factors; D000368:Aged; D015415:Biomarkers / Q000097:blood; D005260:Female; D013006:Growth Hormone / Q000097:blood; D006131:Growth Inhibitors / Q000097:blood*; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000032:analysis*; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D008297:Male; D008875:Middle Aged; D013002:Somatomedins / Q000032:analysis*
D015415:Biomarkers; D006131:Growth Inhibitors; D018972:Insulin-Like Growth Factor Binding Protein 3; D013002:Somatomedins; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone