Remission criteria for the follow-up of patients with acromegaly

Abstract

Objective: The aim was to evaluate the validity of current remission criteria in acromegaly, a random GH level of ,2.5 mg/l, a glucose-suppressed GH level of , 1 mg/l and a normal IGF-I level. Design: In forty-one patients treated for acromegaly (23 males and 18 females, 20-69 years) and 94 healthy subjects (50 males and 44 females, 20-78 years), basal GH and IGF-I levels and nadir GH levels after 75 g oral glucose were evaluated in decade blocks; these were assayed by sensitive immunoradiometric assays. Results: Basal GH levels varied widely from 0.022 to 10.4 in healthy subjects and were .2.5 mg/l in 19%. The mean post-glucose GH nadir was 0.067^0.009 mg/l (range 0.003 -0.4 mg/l) and the upper limit of the GH nadir was 0.26 mg/l (means þ 2 S.D.) in healthy subjects. Thirty-five patients with acromegaly had high-for-age IGF-I levels in relation to our healthy subjects. In this group, 15 (42.9%) patients had basal GH levels of , 2.5 mg/l, 14 (40%) patients had nadir GH levels of , 1 mg/l, and three (8.6%) patients had GH suppression to , 0.26 mg/l which was defined as normal GH suppression in our healthy subjects. Only six patients with acromegaly had normal-forage IGF-I levels and all of these patients had basal GH levels of , 2.5 mg/l and all but one had nadir GH levels of ,0.26 mg/l. Conclusions: A basal or random GH level of ,2.5 mg/l is not a reliable criterion for remission in acromegaly and the currently accepted normal upper limit of 1 mg/l for post-glucose GH suppression is too high. Post-glucose nadir GH levels, measured with sensitive assays, can be , 1.0 mg/l in 40% and basal GH levels can be , 2.5 mg/l in 43% of the active acromegalic patients. IGF-I levels appeared to correlate better with a nadir GH cut-off of 0.26 mg/l rather than 1 mg/l in the determination of disease activity. European Journal of Endocrinology 150 465-471

Effect of Sex and Assay Method on Serum Concentrations of Growth Hormone in Patients with Acromegaly and in Healthy Controls

“…In the consensus statement issued in 2000 (2 ), a nadir concentration of 1 g/L in the OGTT, as measured by a sensitive immunometric assay, was used to define normalization of GH secretion, but this limit has recently been criticized for being too high (15 ). Differences in basal serum GH concentrations between healthy men and women have been observed in several studies (16 -20 ), but the nadir value during the OGTT has differed in some (18,19,21 ) but not in other studies (5,20 ).…”

Measurement of basal GH in the diagnosis of acromegaly

“…(3) reported basal GH levels > 5 µg/L in only 10% and > 10 µg/L in < 3% of 213 subjects aged 20 to 76 years, with a predominance of females (69%). These cut-off values (5 µg/L for men and 10 µg/L for women) also show high specificity when GH is measured with other currently available assays (3,(6)(7)(8)(9). It is important to note that the specificity of basal GH measurement using the cut-off values cited above is as high as the specificity of nadir GH in the OGTT considering the currently proposed cut-off of 0.4 µg/L (3,4,6).…”

Limited utility of oral glucose tolerance test in biochemically active acromegaly

“…While some of them have suggested that the 1 mg/l cut-off level was satisfactory (4,5,7,13,14), others have suggested that lower cutoffs should be utilized to better define remission of acromegaly (8,9,(15)(16)(17)(18). We show here that the utility of OGTT is determined by the degree of endogenous GH hypersecretion: 100% of clinically and biochemically active acromegalic patients with 'high' GH profiles have postglucose GHn higher than 1 mg/l, while over 50% of the active 'low' GH acromegalic patients have ostensibly normal GH suppressibility by the same criterion.…”