Aminoaciduria in calcium-deficiency rickets in northern Nigeria

Generalized aminoaciduria is associated with vitamin D-deficiency rickets in humans, but there is little information regarding aminoaciduria in rickets caused by primary calcium deficiency. In contrast to rickets in other parts of the world, this bone disease in Nigeria is caused primarily by inadequate intake of dietary calcium. We conducted a clinical trial in Jos, Nigeria in 10 children with radiographically and biochemically proven rickets; an equal number of non-rachitic healthy children from the same area served as controls. Serum and 24 h urine samples were obtained at baseline and at 24 h, 1 week, 4 weeks, and 12 weeks after initiation of calcium supplementation (1000 mg/day) and were analysed for their content of amino acids. Serum calcium, phosphorus, intact parathyroid hormone (PTH), 25-hydroxyvitamin D, and 1,25-dihydroxyvitamin D were also measured at each time point. In the rachitic subjects urinary amino acid concentrations were elevated from 2- to 16-fold at baseline, while serum amino acid levels increased 1.5- to 3.8-fold compared to controls. After 12 weeks of calcium supplementation, serum and urine amino acids decreased. There was no correlation between the degree of aminoaciduria and serum PTH or 1,25-dihydroxyvitamin D concentrations. We conclude that the aminoaciduria in these rachitic children was related to their calcium status and not to their vitamin D or PTH status.