Endocrine Abstracts

In acromegaly bone mineral density depends on gonadal function

M Kochman, W Zgliczynski, W Misiorowski, P Zdunowski, L Papierska & S Zgliczynski

Dept. of Endocrinology, Medical Center of Postgraduate Education, Warsaw, Poland.

The aim of the study was to evaluate factors determining bone mineral density (BMD) and serum concentrations of osteocalcin (OC) and carboxyterminal telopeptide of type I collagen (ICTP) in acromegaly. Material consisted of 121 patients with active acromegaly, aged 23–80 years. In the whole group BMD, assessed by DXA, was: 0.35±0.15 at L₂–L₄, 0.60±0.11 at femoral neck, 0.05±0.12 at Ward’s triangle and 0.59±0.13 at trochanter and was higher than normal at all sites excluding Ward’s. Mean serum OC was 31.7±2.2 ng/ml, and ICTP – 7.3±0.5 μg/l. OC and ICTP were higher than normal and positively correlated with each other and with IGF-I concentration. IGF-I was the main factor determining OC. For ICTP and Z-scores the most important were gonadal status and gender. ICTP negatively correlated with Z-scores. One third of the acromegalics were eugonadal, whereas 2/3 were hypogonadal. Z-scores in eugonadal group were higher than normal. Hypogonadal subjects had significantly lower Z-scores and higher ICTP than eugonadal ones. Of hypogonadal patients: 27% had osteopenia and 7% – osteoporosis. When compared to females, males had lower Z-scores and higher ICTP concentrations. Postmenopausal subjects had lower Z-scores than eugonadal females. In the group of women with gonadal function adequate to age the main factor determining Z-scores was estrogen deficiency.

Conclusions: GH-excess in acromegaly leads to increase of BMD, by stimulation of IGF-I-dependent bone turnover, with prevailing synthesis. In hypogonadal acromegalics (2/3 of the population), high bone resorption may cause a decrease of BMD and osteoporosis. Acromegalic males have relatively higher bone resorption and lower BMD than females. The influence of GH on BMD in acromegalic females with preserved gonadal function is stronger than in postmenopausal acromegalics. This suggests synergic effect of GH and estrogens on bone.

Endocrine Abstracts (2006) 11 OC52