LAUSR

Due to inconvenience of a 24-hour urinary collection, spot urine-based diagnostic approaches are increasingly popular. Spot urine sodium measurements are potential replacement for 24-hour urinary sodium excretion (24hUNa), considered a surrogate measure of dietary sodium intake. Spot urine-based approaches to estimating 24hUNa and 24-hour urinary potassium excretion (24hUK) are potentially useful in hypertensives, for example to identify increased urinary potassium excretion in patients with primary aldosteronism and high dietary sodium intake in patients with resistant hypertension. In the present review, we have summarized our research on spot urine-based estimation of 24hUNa, 24hUK, and 24-hour urinary creatinine excretion (24hUCr) to avoid the need for a 24-hour urine collection in hypertensives. We found that the PAHO formula was generally the best for predicting average 24hUNa and 24hUK in hospitalized hypertensive patients, while the Kawasaki equation was inferior for estimating 24hUNa, and the Tanaka equation was inferior for estimating 24hUK. However, all three equations were imprecise in terms of estimating individual 24hUNa or 24hUK. We also confirmed general utility of the 24hUCr-estimating equations in hypertensives but with significant differences between various equations, the best formulas being the CKD-EPI and Rule equations. Compared to the combined PAHO/CKD-EPI formula, the Tanaka and Kawasaki equations underestimated increased 24hUNa and/or 24hUK and thus the combined PAHO/CKD-EPI formula might be the best for identifying increased 24hNa and 24hUK in hypertensive patients.