PHOSPHATE DEFICIENCY AS A RARE CAUSE OF OSTEOMALACIA - CASE-REPORT OFPARENTERAL-FEEDING AND ANTACID TREATMENT

History and clinical findings: Floor-of-the-mouth cancer had been diag nosed and surgically treated in a 55-year-old man 4 years before the l atest admission, For the last 3 years he had been fed through a percut aneous endoscopic gastrostomy (PEG). Since then he had experienced ref lux oesophagitis which was being treated with aluminium-containing ant acids, He was hospitalized for the surgical treatment of bilateral fra ctures of the neck of the femur, A surgical biopsy revealed osteomalac ia but no metastasis. Investigations: The serum phosphate level was si gnificantly reduced (0.21 mmol/l) and there was no detectable phosphat e excretion in the 24-hour urine. Serum calcium concentration was unre markable, but there was hypercalciuria (34.4 mmol/d). Alkaline phospha te activity was significantly raised (393 U/l) and parathormone level reduced (7 ng/l). Vitamin D concentration was unremarkable. Treatment and course; The phosphate content in the parenteral feed was at first increased and additional phosphate was given by mouth. The calcium and phosphate levels slowly became normal only after medication had been changed from antacids to Hz-blockers. Conclusions: In this case osteom alacia was caused not by vitamin D deficiency but by a lack of phospha te, The reduced intestinal phosphate absorption by the antacids only p artially explains the pronounced clinical signs. if antacids are taken over long periods the phosphate balance should be carefully monitored to avoid osteomalacia.