Loop diuretics are K+-sparing in the presence of a low-Na+, high-K+ diet.

Under most conditions, loop diuretics are K+-wasting, requiring potassium supplementation. In this issue, Wang and colleagues demonstrate that in mice fed a low-Na+, high-K+ diet, loop diuretics, in contrast, are K+-sparing. This observation suggests that possible elevations in plasma K+ should be monitored when using a loop diuretic with a low-Na+, high-K+ diet, particularly when in combination with a potassium supplement.