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A 53-year-old man on hemodialysis suffered from short bowel syndrome after subtotal colectomy and partial resection of the small intestine. Laboratory tests showed multiple electrolyte disorders and enlarged sodium and chloride ion (Cl(−)) gaps despite treatment with large volume of sodium chloride replacement via central venous infusion. Blood gas analysis showed slightly high bicarbonate ion levels and metabolic alkalosis was suspected, which is uncommon in end stage kidney disease. The measurement of electrolytes in feces from ileostomy showed relatively high Cl(−) excretion. The loss of Cl(−) to feces may have caused the metabolic alkalosis; thus, additional Cl(−) replacement may have been necessary.

Selectivity index (SI) of proteinuria, calculated using the clearance ratio of immunoglobulin G to transferrin, predicts the response to glucocorticoids in patients with nephrotic syndrome. However, there is disagreement regarding the suitability of SI. Therefore, alternate indices should be considered. This study investigated whether or not selectivity index protein fraction (SIPF) was inferior to SI for the prediction of the response to glucocorticoids.Forty-nine patients with nephrotic syndrome were evaluated. On the basis of molecular weight and protein fraction, as an inexpensive substitute for SI, the clearance ratio of the albumin to γ fractions measured in serum and urine protein fractions was defined as SIPF. The quality of SIPF was examined. Moreover, the best cutoff value of SIPF was determined; and SIPF distribution, according to histopathological diagnosis by renal biopsy, was examined.SIPF was strongly correlated with SI (r = 0.79, P 0.001). The area under the receiver operating characteristic (ROC) curve of SIPF and SI was not significantly different (P = 0.18). The best cutoff value of SIPF was 0.45. In the group with SIPF 0.45, only two patients with minimal change disease (MCD) achieved complete remission. In the group with SIPF ≤ 0.45, all patients with MCD achieved complete remission, although eight patients with other histopathological diagnoses did not achieve complete remission.Analysis of protein fractions as a substitute for SI may be useful for predicting response to glucocorticoids in patients with nephrotic syndrome.