The correct answer is:
This could be Renal Osteodystrophy, however the age of the child and severity of the bone changes make this less likely. Also normal calcium and phosphorus make this much less likely as the cause. The etiology of renal rickets is that damage to the glomerulus causes retention of phosphorus while tubular injury reduces the production of 1,25 vit D. Hyperphosphatemia further suppresses the production of 1,25 vit D and inhibits renal reabsorption and GI absorption of Ca. Renal osteodystrophy is characterized by rickets, osteitis fibrosa (severe lysis of the skeleton due to secondary hyperparathyroidism), osteosclerosis (20%),and ectopic calcification.
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