Application Value of Random Urine Potassium-to-Creatinine Ratio in Diagnosing Renal Potassium Loss

  Objective   To analyze the value of applying random urine potassium-to-creatinine ratio (rUK/Ucr) in diagnosing renal potassium loss.

  Methods   patients diagnosed with hypokalemia, including 373 cases of renal potassium loss, 83 cases of non-renal potassium loss , and 358 cases of normal serum potassium, between 2017 and 2021 were enrolled. The clinical data of the patients were collected and the correlation between rUK/Ucr and 24-hour urine potassium (24 hUK) in the three groups was analyzed. The receiver operating characteristic (ROC) curve was used to analyze the value of applying rUK/Ucr in diagnosing renal potassium loss.

  Results   Serum potassium decreased in the normal serum potassium group, the renal potassium loss group, and the non-renal renal potassium loss group (P<0.01). The 24 hUK and the rUK/Ucr of the renal potassium loss group were higher than those of the non-renal potassium loss group and normal serum potassium group (P<0.01). rUK/Ucr showed low to moderate correlation with 24 hUK. The AUC of 24 hUK and rUK/Ucr for determining renal potassium loss were 0.73 and 0.71, respectively. When the optimal cutoff point of rUK/Ucr for determining renal potassium loss was 3.4, the sensitivity was 67.6% and the specificity was 67.5%.

  Conclusion   rUK/Ucr shows a moderate correlation with 24 hUK and its accuracy in determining renal potassium loss is comparable to that of 24 hUK. When 24-hour urine samples cannot be obtained, it is recommended that rUK/Ucr be used instead of 24 hUK to determine whether renal potassium loss exists, with the optimal cutoff point for diagnosis being 3.4.