Abstract
Four patients had symptomless osteomalacia at the time of starting regular haemodialysis. After 21-40 months they became hypophosphataemic and developed disabling skeletal symptoms. In each case an exacerbation of histological osteomalacia was shown. Symptoms improved after measures designed to raise serum inorganic phosphate concentrations or vitamin D administration, or both. Patients undergoing maintenance haemodialysis should have their serum phosphate and alkaline phosphatase levels monitored every month. Predialysis phosphate levels below 1 mmol/1 (3 mg/100 ml) and rising serum alkaline phosphatase concentrations are danger signals. If the diagnosis is confirmed early aggressive treatment should be started.