METABOLIC BONE-DISEASE IN BLACK TEENAGERS WITH GENU-VALGUM OR GENU-VARUM WITHOUT RADIOLOGIC RICKETS - A BONE HISTOMORPHOMETRIC STUDY

Calcium deficiency in black (African) children can cause rickets and o steomalacia with severe limb deformities. It is not known whether blac k teenagers with genu valgum or varum but without radiologic rickets s uffer from a related disorder. To examine this question we studied 26 such patients by iliac crest bone biopsy and serum and urine biochemis try: 12 patients (46%) had osteopenia with normal or low bone turnover , 5 (19%) mildly increased bone turnover, 4 (15%) histologic hyperpara thyroidism, 2 (8%) preosteomalacia, and 3 (12%) osteomalacia (with fea tures of hyperparathyroidism). Radiographs did not reflect the severit y of the bone disease. Serum calcium levels correlated inversely with eroded mineralized surface (p < 0.001), osteoid surface (p < 0.01), os teoid thickness (p < 0.001), mineralization lag time (p < 0.001), and 1,25-(OH)2 vitamin D (p < 0.005), and 1,25-(OH)2 vitamin D correlated positively with osteoid surface (p < 0.05), osteoid thickness (p < 0.0 5), osteoid volume (p < 0.01), eroded surface (p < 0.05), and eroded m ineralized surface (p < 0.0005). Tubular reabsorption of phosphate and 25-OH vitamin 1) levels were normal, and 1,25-(OH)2 vitamin D levels were normal to high. This suggests that calcium deficiency may have ca used the increase in bone turnover and the mineralization defects. The most severe osteomalacia was found in males aged 16-19 years. We cann ot explain the cause of the osteopenia. We conclude that all patients had bone disease.