1. The histological appearances of cancellous bone from the ilium have been quantified in thirteen patients with osteomalacia due to chronic renal failure. 2. There was an excess of osteoid tissue and a reduction in the extent of the calcification front in that osteoid lamella lying next to calcified bone. 3. Administration of calcium compounds orally produced an increase of punctate calcification within the osteoid, but there was no change in the extent of the calcification front. 4. Administration of vitamin D produced a marked rise in the extent of the calcification front but no increase of punctate calcification within the osteoid. 5. This rise in the extent of the calcification front was not dependent on a rise in plasma calcium × plasma phosphorus product. 6. It is concluded that vitamin D has a direct action on the bone in patients with the osteomalacia of chronic renal failure.
1. Iliac bone biopsies were obtained from nine patients 3 months to 6 years after bilateral nephrectomy. 2. In eight of the nine patients no histological evidence of vitamin D abnormality was seen in the bones after bilateral nephrectomy. 3. One patient showed histological evidence of osteomalacia before bilateral nephrectomy which improved but did not disappear after bilateral nephrectomy. 4. The biospies of all nine patients showed evidence of hyperparathyroidism. 5. It is concluded that normal bone mineralization can take place in the absence of the kidneys.