Urinary oxalate on a high-oxalate diet as a clinical test of malabsorption.

100 g of spinach a day was added to the hospital diet of fifty-four patients with suspected malabsorption. Hyperoxaluria was found in thirty-eight patients; all of them had steatorrhoea. No patient with steatorrhoea had a urinary oxalate excretion of less than 40 mg a day. Ten other patients had hyperoxaluria, but the faecal fat determinations were regarded as unreliable in almost all and malabsorption could not be confirmed. It is suggested that in clinical practice determination of urinary oxalate after an oral load of oxalate could replace faecal fat determination in most patients with suspected malabsorption.