Can people with chronic kidney disease take retatrutide?

Only inside a clinical trial, because retatrutide is not FDA approved. The first phase 2 trials excluded people with eGFR below 45. TRANSCEND-CKD and TRANSCEND-T2D-3 were set up to study people with reduced kidney function.

Does retatrutide damage the kidneys?

The phase 2 trials did not show a clear kidney injury signal, and serious events were rare. The unusual rise in eGFR in people with obesity is not yet understood. Dehydration from vomiting or diarrhea is a known kidney risk for this drug class.

Why would a weight-loss drug lower urine protein?

Weight loss, lower blood pressure and better blood sugar can all ease strain on the kidney filters. Researchers also think the glucagon part of retatrutide may act on the kidney directly. The exact mechanism has not been proven.

Should my kidney labs be read differently if I lose a lot of weight?

Possibly. Creatinine comes mostly from muscle, and cystatin C is made mainly by fat tissue, so big weight changes can shift both. The retatrutide researchers suggested cystatin C may be the better marker, but this needs confirmation.

Is retatrutide better for the kidneys than semaglutide?

No one knows. Semaglutide has a completed kidney outcome trial, FLOW, that showed a 24% lower risk of the main kidney and heart composite outcome. Retatrutide has only marker data so far, with outcome results expected from TRIUMPH-Outcomes.

How Does Retatrutide Affect Kidney Function?

The short answer: In phase 2 trials, higher doses of retatrutide lowered urine albumin by about 28% to 37% compared with placebo. Estimated kidney filtration (eGFR) dipped at first, then rose above baseline in people with obesity. Nobody knows yet if that rise is good or harmful, and no trial has shown that retatrutide protects the kidneys. Retatrutide is investigational and not FDA approved.

What do eGFR and UACR tell you about the kidneys?

Doctors use two main blood and urine tests to track kidney health. Both appear in the retatrutide research.

eGFR (estimated glomerular filtration rate): an estimate of how much blood the kidneys filter each minute. The NIDDK calls it a key marker for chronic kidney disease. It is usually calculated from creatinine, cystatin C, or both.
UACR (urine albumin-to-creatinine ratio): a measure of the protein albumin in urine. MedlinePlus explains that healthy kidneys let only trace amounts through. Damaged kidneys can leak large amounts.

A lower UACR is generally a good sign. The meaning of a change in eGFR depends on why it changed, and that question sits at the center of the retatrutide story.

What did the retatrutide trials show for kidney markers?

The main published data come from a 2025 analysis in Kidney International Reports. Researchers from the University Medical Center Groningen and Eli Lilly looked back at two phase 2 trials. One enrolled 281 adults with type 2 diabetes. The other enrolled 338 adults with overweight or obesity but no diabetes.

Key results compared with placebo:

Type 2 diabetes, 36 weeks: the 12 mg group had UACR about 37% lower. eGFR was unchanged.
Obesity, 48 weeks: UACR was 28% lower on 8 mg and 31.5% lower on 12 mg.
Obesity, 48 weeks: creatinine-based eGFR was higher by 5.3 (8 mg) and 8.5 (12 mg) mL/min/1.73 m².

The authors note that a drop in albuminuria of more than 30% is linked with a high chance of reducing kidney outcomes. Still, most people in these trials had normal albumin levels at the start. Median baseline UACR was only 13 mg/g in the diabetes trial and 7 mg/g in the obesity trial. So the absolute change was small.

These numbers come from trial doses studied under close monitoring. They are not a guide to how anyone should use the drug.

Why does eGFR dip and then rise on retatrutide?

eGFR dropped in the first 12 weeks in both trials. This early dip also happens with GLP-1 and GIP/GLP-1 drugs, such as semaglutide and tirzepatide. The authors link it to lower blood pressure, better blood sugar and weight loss, which can ease pressure inside the kidney filters.

What came next was new. In people with obesity, eGFR climbed 5 to 10 points above baseline with creatinine, and 10 to 15 points with cystatin C. The authors wrote that this pattern had not been seen with any other drug, to their knowledge. Most of the rise went away within 4 weeks of stopping the drug.

The likely driver is the glucagon part of retatrutide. Retatrutide acts on GIP, GLP-1 and glucagon receptors (see how a triple agonist works). The TRANSCEND-CKD design paper notes that glucagon infusion raises filtration in rodents and humans.

Is a higher eGFR a good sign or a warning sign?

It is not yet known. There are two competing readings.

Benign reading: the rise came with lower albuminuria, which suggests less kidney stress. The Groningen authors lean toward this view.
Cautious reading: the TRANSCEND-CKD paper says the rise could reflect higher pressure inside the kidney filters. Over time, that can lead to hyperfiltration and structural damage.

There is also a measurement problem. Creatinine comes mostly from muscle, and cystatin C is made mainly in fat tissue. Large weight loss can shift both markers without any real change in filtration. The authors found that cystatin C results did not track weight change, so they suggest it is the better marker during retatrutide treatment. The only way to settle this is to measure filtration directly.

Did retatrutide cause kidney injury in trials?

Serious kidney problems were rare in the phase 2 trials. The published kidney analysis reports these events:

In the diabetes trial, the one serious acute kidney injury was in the placebo group.
In the obesity trial, one serious acute kidney injury occurred at 8 mg. It was thought to be possibly linked to a COVID-19 infection.
Dehydration was reported in 4 people in the obesity trial, and 3 were on retatrutide.
Low blood pressure or dizziness on standing affected 9 people in that trial. Eight were on retatrutide.

No clinically important changes in electrolytes were seen. These trials excluded people with eGFR below 45, so they say little about people with advanced kidney disease.

The class warning still matters. The Ozempic (semaglutide) FDA label warns of acute kidney injury from volume depletion. It cites postmarketing reports, some needing dialysis, mostly in people with nausea, vomiting or diarrhea that led to dehydration. Retatrutide causes the same kind of stomach side effects, which our retatrutide side effects guide covers.

Which trials will show whether retatrutide protects the kidneys?

Three registered trials target kidney questions:

TRANSCEND-CKD (NCT05936151): a phase 2 trial of 146 adults with overweight or obesity and chronic kidney disease (eGFR 25 to 75), with or without diabetes. It measures true filtration with iohexol clearance at 24 weeks, plus kidney MRI. The registry lists it as completed in October 2025, but no results were posted when we checked.
TRANSCEND-T2D-3 (NCT06297603): about 320 adults with type 2 diabetes and moderate or severe kidney impairment on basal insulin. Primary completion is estimated for October 2026.
TRIUMPH-Outcomes (NCT06383390): about 10,000 adults with obesity plus heart or kidney disease. It has a kidney composite endpoint, and primary completion is estimated for February 2029. Our cardiovascular outcome trials article covers it in detail.

For comparison, semaglutide already has kidney outcome data. In the FLOW trial described in the Ozempic label, 3,533 adults with type 2 diabetes and chronic kidney disease were followed for a median of 41 months. Semaglutide 1 mg cut the main kidney and heart composite outcome by 24% (hazard ratio 0.76). That result belongs to semaglutide and cannot be assumed for retatrutide. More on semaglutide is at ozempic.md.

The bottom line

Retatrutide lowered urine albumin in phase 2 trials, which is an encouraging early signal. It also raised eGFR above baseline in people with obesity, a pattern not seen with other incretin drugs. Researchers do not yet know if that rise protects or strains the kidneys. People with kidney disease were mostly left out of the early trials. Answers should come from TRANSCEND-CKD results and, later, TRIUMPH-Outcomes. Until then, retatrutide should be used only inside clinical trials.

Last updated: September 2026. This article is for informational purposes only and does not constitute medical advice. Anyone with kidney disease who is thinking about a weight-loss drug or trial should talk with a nephrologist or their prescriber.