Detecting the early stages of osteomalacia with the intravenous vitamin D test.

Studies of calcium levels in 400 elderly patients in a hospital geriatric unit showed that many patients (42 percent) had hypocalcemia when referred to the unit and that the incidence of hypocalcemia rises proportionately with advancing age; however, in men, the frequency decreases after age 90. Although hypocalcemia is caused by vitamin D deficiency in a number of patients, in most it is caused by malnutrition. The intravenous vitamin D tests is a simple and reliable procedure for differentiating hypocalcemia due to specific vitamin D deficiency from that due to other causes. We suggest that a 15 percent rise in the serum phosphate level after the intravenous administration of 40,000 units of vitamin D3 indicates the presenceof osteomalacia. Little is known about the sequence of development of detectable bone changes and disturbance of serum calcium, phosphate, and alkaline phosphatase levels in the natural course of osteomalacia. Early treatment of osteomalacia is simple and very rewarding. No effort should be spared in detecting it as soon as possible.