Urine protein excretion in acute pancreatitis.

The mechanism of the increased renal clearance of amylase and the amylase to creatinine clearance ratio (CAM/CCR) in acute pancreatitis remains controversial with both renal tubular dysfunction and altered glomerular permeability being invoked as explanations. To differentiate between these mechanisms, we investigated the quantity and character of protein excretion in 10 patients with pancreatitis. For a short period of time, seven of 10 patients had mild proteinuria with a mean protein excretion rate of 230 +/- 154 mg/24 hr. Proteinuria decreased in 9/9 survivors to 17 +/- 18 mg/24 hr. Albumin excretion rate initially was minimally increased in 10/10 patients with a mean of 61 +/- 40 mg/24 hr, decreasing during recovery in 8/9 survivors to 10.9 +/- 10.4 mg/24 hr (P less than 0.01). Electrophoresis of urine obtained during the acute phase consistently showed a low molecular weight proteinuria pattern that cleared with recovery. Twenty-one of 22 urinary samples with an elevated CAM/CCR had a low molecular weight protein pattern. All the above findings can be explained by alterations in renal tubular reabsorption of proteins without changes in glomerular permeability. In 2/4 patients a low molecular weight protein was present in urine specimens from the acute phase that was not present in highly concentrated urine specimens from the recovery period. This raises the possibility that an abnormal low molecular weight protein enters the serum in acute pancreatitis, which, after glomerular filtration, produces the renal tubular malfunction found in acute pancreatitis.