The syndrome of hyperostosis and hyperphosphatemia.

Six children, five girls and one boy, presented with recurrent episodes of swelling, pain, and tenderness of the long bones. On roentgenographic examination all had cortical hyperostosis of the affected areas. Serum phosphate concentration was persistently elevated, and calcium values were normal. Bone biopsy and histologic examination in three patients revealed periosteal new bone formation. The Ellsworth-Howard test was performed on three patients; all had a normal phosphaturic response and an increase in urinary c'AMP to exogenous PTH. The EDTA test, performed on one patient, demonstrated significant phosphaturic response, but a minimal drop in serum phosphate concentration. These findings suggest that the association of cortical hyperostosis and hyperphosphatemia is a distinct clinical entity, and that hyperphosphatemia results from decreased renal excretion of phosphate.