Vitamin D3 metabolism in idiopathic osteonecrosis of femoral head.

Eighteen cases of idiopathic osteonecrosis of the femoral head were studied. Serum concentrations of 25(OH)D3, 24, 25(OH)2D3 and 1,25(OH)2D3 were 19.4 +/- 8.7 ng/ml, 1.04 +/- 0.44 ng/ml and 16.7 +/- 7.9 pg/ml (mean +/- SD) respectively. These values were significantly lower than those of control (26.5 +/- 15.5 ng/ml, 1.91 +/- 0.77 ng/ml and 26.9 +/- 13.7 pg/ml, respectively) (p less than 0.01). Abnormal values of serum calcium (Ca) were detected in two cases, inorganic phosphate (iP) in two cases and alkaline phosphatase (Al-Pase) in two others with no other abnormal values in blood biochemistry. Histological findings in nine cases of iliac bone were those of osteomalacia in five cases and those of osteoporosis in four cases. These results suggest the possibility of bone metabolism abnormalities due to abnormal vitamin D3 metabolism as a background of osteonecrosis of the femoral head.