[The frequency and mechanisms of urolithiasis in acromegaly]

It is generally accepted that acromegaly is often associated with hypercalciuria, but there are few reports on the frequency and the mechanisms of urolithiasis. Recently we consecutively experienced 2 cases of acromegaly with urolithiasis, and these experiences made us investigate the association between urolithiasis and acromegaly. Among 18 acromegalies from 1977 to March 1990 (10 males, 8 females, 24-64 years old), 13 cases (72%) fulfilled the criteria of hypercalciuria (urinary calcium (u-Ca) greater than or equal to 200 mg/day or u-Ca/urinary creatinine (u-Ca/u-Cr) greater than or equal to 0.15), and 7 cases (39%) suffered from urolithiasis that was diagnosed by KUB (4 cases) or X-ray computed tomography (CT) (3 cases). Especially in the last 2 years, 5 out of 7 cases (71%) were complicated with urolithiasis and all 7 cases were associated with hypercalciuria. These results suggest that hypercalciuria and urolithiasis are both much more frequent than previously reported. In 6 cases who were treated by pituitary adenomectomy from 1988-1989 (4 males, 2 females, 24-59 years old), we examined Ca metabolism before and after operation. Before operation, the levels of serum growth hormone (GH), u-Ca (mg/day), u-Ca/u-Cr (in all cases) and plasma somatomedin-C (Sm-C) (in 4 cases) were increased above the normal range. To determine the etiology of hypercalciuria, we performed the oral Ca load test under restriction of Ca (400 mg/day) and P (650 mg/day) intake. The results suggested that the hypercalciuria might be mainly due to the increased absorption of Ca from the intestine (so-called "Absorptive hypercalciuria"). However, the levels of serum vitamin D (Vit. D) metabolites were all within the normal range before operation. After operation, GH and u-Ca/u-Cr (in 5 cases) and u-Ca (mg/day) (in all cases) decreased significantly compared with before operation, and the levels of Sm-C (in all cases), serum 25-(OH)D3, 1 alpha, 25-(OH)2D3 (in 4 cases) and 24,25-(OH)2D3 (in 3 cases) were also reduced after operation. Surprisingly, u-Ca and u-Ca/u-Cr normalized only in 4 cases who showed a reduction in 1 alpha, 25-(OH)2D3 levels after operation, although there were no correlations between u-Ca (mg/day) or u-Ca/u-Cr and 1 alpha, 25-(OH)2D3. Significant correlations were found between u-Ca (mg/day) or u-Ca/u-Cr and Sm-C. The parathyroid function evaluated by the rapid Ca infusion test or nephrogenous cyclic adenosine monophosphate (NcAMP) was normal before and after operation.(ABSTRACT TRUNCATED AT 400 WORDS)