Diuretic Urine Test Offers Clarity on Kidney Recovery

Published: June 8, 2025

If you're wondering whether urine can tell us more than just hydration status — science says yes, especially when kidneys are involved. A new study out of Critical Care finds that a dose of furosemide (a common diuretic) may be the crystal ball nephrologists need to predict which patients can safely stop kidney replacement therapy.

From Output to Outlook: What the Study Found

Researchers tested a concept called the furosemide stress test (FST) on critically ill patients with acute kidney injury (AKI) who were already receiving kidney replacement therapy (KRT). Patients had to be producing at least 400 mL of urine on their own in a 24-hour period without any help from diuretics. After that, they received IV furosemide — and the team watched closely.

A “positive” result? That meant producing over 200 mL of urine in just 2 hours. And the implications were big. Patients who passed the test had a much lower chance (14.5%) of needing to resume KRT in the following week. Those who didn’t pass? Over 72% were back on therapy within days. The urine was speaking loud and clear.

The AUC is Not Just a Fancy Acronym

Statistically speaking, the test held its own. The area under the curve (AUC) — a way to measure the accuracy of a test — came in at 0.87. That’s considered pretty strong. The conclusion? If a critically ill patient with AKI is making urine, the FST is a powerful predictor for successful short-term recovery.

Why It Matters

While it might not make headlines like celebrity drama or billion-dollar lawsuits, this finding could change how doctors manage one of the most high-stakes aspects of critical care. Knowing when to stop dialysis isn’t just a clinical decision — it’s often a race against time, side effects, and rising costs. And as it turns out, urine might just be the unexpected hero of kidney rehab.

Read the full summary via Physicians Weekly.