Influence of three different types of hypercalciuria on bone

Abstract

 The relationship between bone mineral status and hypercalciuria is controversial. The effect on bone composition of different forms of hypercalciuria was studied in female rats made hypercalciuric by 7-week administration of oral furosemide (F, n=12), intraperitoneal 1,25-dihydroxy vitamin D (VD, n=11), or oral ammonium chloride (AC, n=12). Seven untreated rats served as controls (C). Hypercalciuria (mg/100 g per 24 h, mean ±SEM) of F (4.3±0.2), VD (4.1±0.4), and AC (3.9±0.3) groups was of similar intensity (C rats 1.3±0.1, P<0.01). Weight and length gains and serum CO₂, sodium, potassium, calcium, and phosphate were no different among the four groups. Bone was studied by dual-energy X-ray absorptiometry of left tibiae. AC rats had significantly less bone area (1.505±0.018 cm²) than VD and C (1.602±0.020 and 1.587±0.019 cm²). Bone mineral content was decreased in F (0.357±0.007 g) and AC (0.362±0.006 g) compared with VD (0.407±0.008 g) and C (0.389±0.009 g) groups. Bone mineral density was different between F (0.231±0.002 g/cm²) and VD and C rats (0.254±0.004 and 0.245±0.003 g/cm²), and also between AC (0.240±0.003 cm²) and VD rats. In these rat models, hypercalciuria of renal origin (F) and hypercalciuria caused by acid load (AC) adversely impaired bone mass.