A COMPARISON OF DIFFERENT METHODS FOR DIAGNOSING ACROMEGALY

OBJECTIVE The present study was designed to assess the diagnostic valu e of different single measurements in comparison to the classic time-c onsuming method, the oral glucose tolerance test (OGTT), in acromegaly . DESIGN, PATIENTS AND MEASUREMENTS IGF-I, free IGF-I, 24-hour-urinary GH (uGH), serum IGFBP-3 and 24-hour-urinary IGFBP-3 (ulGFBP-3) were m easured in 12 patients with untreated active acromegaly, in 29 patient s who had been treated but were not cured, in 13 patients with cured a cromegaly and in 14 healthy control subjects, and compared with the re sults of the OGTT. RESULTS In all patients with active acromegaly, whe ther they had been treated or not, nadir GH in OGTT was >3 mU/l, where as nadir GH was <1.8 mU/l in the cured patients and the control subjec ts. In patients with untreated active acromegaly IGF-I, free IGF-I, UG H and IGFBP-3, but not ulGFBP-3, were significantly higher than in hea lthy individuals (P < 0.0001). Only IGF-I values did not overlap with the control group. In those patients with acromegaly who had been trea ted but not cured these parameters overlapped with the control group. In patients with acromegaly there was a significant correlation betwee n nadir GH levels in OGTT and IGF-I (r = 0.71), free IGF-I (r = 0.76), IGFBP-3 (t = 0.73) and uGH (r = 0.81) (P < 0.0001), but no correlatio n with ulGFBP-3. CONCLUSIONS Only be means of the OGTT could patients with active acromegaly be completely distinguished from the control su bjects and from cured patients. IGF-I, free IGF-I, IGFBP-3 and uGH wer e useful in the diagnosis of acromegaly, but of limited value in the f ollow-up of acromegalic patients after treatment. The determination of free IGF-I, which has yet not been investigated in acromegaly, offere d no advantage over that of total IGF-I and IGFBP-3; ulGFBP-3 was not useful in the diagnosis of acromegaly.