Phosphate excretion in reflex sympathetic dystrophy syndrome before and after a single infusion of pamidronate

To clarify the relations between reflex sympathetic dystrophy syndrome and moderate phosphate diabetes, we prospectively determined urinary phosphate excretion parameters (clearance, renal tubular reabsorption of phosphate and threshold of tubular reabsorption of phosphate) in 37 patients with reflex sympathetic dystrophy syndrome before and after treatment with 60 mg of pamidronate (n = 23) and in 35 age- and sex-matched controls. Urinary phosphate excretion parameters were identical in cases and in controls. Fourteen of the 23 cases treated by pamidronate were improved after one to two months. Pamidronate had no effect on phosphate excretion. Four cases versus only one control had phosphate diabetes (X2 = 0.18). Three of the four cases with phosphate diabetes failed to respond to pamidronate therapy but improved under phosphate and 1,25-diOH vitamin D3 therapy.