Objective: This study aimed to evaluate the relevance of ratios of urinary potassium to urinary sodium + potassium (U(K)/U(Na + K)) to edema status in minimal-change nephrotic syndrome (MCNS).
Methods: We retrospectively studied 26 adults with newly diagnosed MCNS with significant pitting edema. On the basis of mean value (0.46±0.21) of U(K)/U(Na + K) determined from spot urine samples on admission, patients were classified into 2 groups.
Results: On admission, 12 of 26 patients had U(K)/U(Na + K) >0.46 (0.65±0.16, Group H), 14 patients had U(K)/U(Na + K) <0.46 (0.29±0.08, Group L). The level of serum albumin was similarly decreased in these 2 groups. Noteworthy were lower urine volume, fractional excretion of sodium (FENa), serum sodium, and higher hematocrit in the group H as compared with the group L. The group H had a shorter mean time required from onset of edema to hospitalization, and tended to have a longer mean time to complete remission than group L. High U(K)/U(Na + K) levels in group H decreased significantly after remission, eventually becoming equal to those of group L (0.24±0.05 vs. 0.25±0.05).
Conclusion: U(K)/U(Na + K) determined from spot urine sample on admission relates to laboratory or clinical indices to distinguish edema status in adult patients with MCNS.