Vitamin D-resistant hypophosphatemic osteomalacia associated with 1, 25(OH)2D3 deficiency, hyperphosphaturia, renal pan-aminoaciduria and glucosuria in a 27 year old woman was cured by resection of a benign osteoblastoma in her knee, with concomitant correction of these abnormalities. Correction of serum 1, 25(OH)2D concentration by oral 1α(OH)D3 administration alone raised serum phosphorus level and %TRP, but not to normal levels.
A tumor-derived substance is postulated to cause reversible impairment of proximal renal functions, leading to hypophosphatemia due to impaired reabsorption and to 1, 25(OH)2D3 deficiency due to impaired formation, both of which caused osteomalacia.
Both intramuscular injections of tumor-homogenate and intravenous infusion of the patient's pre-operative urine in rats increased urinary phosphate excretion significantly. Thus, phosphaturic substance was proved to exist both in the tumor and urine, which supports the above mentioned hypothesis.
