Retatrutide kidney trial results posted: GFR flat, albumin down

Eli Lilly’s full results for TRANSCEND-CKD, a Phase 2b trial of retatrutide in people with chronic kidney disease, were posted to ClinicalTrials.gov on November 9, 2026. The registry record (NCT05936151) shows the drug did not change directly measured kidney filtration compared with placebo over 24 weeks, while urine albumin and body weight fell.

Headline figures from the trial were shown as a poster at the American Society of Nephrology’s Kidney Week 2026 in Denver in October. The registry record is the first public release of the complete outcome tables, and it adds measures the poster summary did not spell out, including kidney volume on MRI, sodium excretion and serious adverse event counts.

The trial

TRANSCEND-CKD randomized 146 adults with overweight or obesity and chronic kidney disease, with or without type 2 diabetes, to once-weekly retatrutide or placebo for about 24 weeks. Lilly first submitted the results to the registry on September 30, 2026, and the study itself was completed in October 2025. Retatrutide acts on the GIP, GLP-1 and glucagon receptors and remains investigational.

The primary endpoint was the change in glomerular filtration rate measured by iohexol clearance, a direct test that does not rely on blood creatinine or cystatin C. According to the Kidney Week abstract, the team chose it because it is less influenced by changes in body composition, which can distort estimated GFR during large weight loss.

What the registry shows

• Measured GFR (primary). At week 24, measured GFR changed by -1.62 on retatrutide and -0.19 on placebo. The difference was -1.44, in the standard units of milliliters per minute per 1.73 square meters of body surface (95% CI -9.17 to 6.30; p of 0.714), so the trial did not show an effect in either direction. The week 16 comparison was also flat (p of 0.925).
• Urine albumin. In participants analyzed for the urine albumin-to-creatinine ratio (23 on retatrutide and 19 on placebo), it fell 53.65% on retatrutide versus 8.75% on placebo, a geometric mean difference of -49.21% (p of 0.017). Twenty-four-hour urinary albumin excretion fell 36.0% versus a rise of 1.5% (p of 0.006).
• Kidney structure and blood flow. Total renal parenchyma volume on MRI shrank by 5.95% on retatrutide versus a 0.19% gain on placebo, and renal cortex volume by 8.38% versus a 0.40% gain. Renal artery resistive index fell (difference -0.04). Mean renal arterial flow and filtration fraction did not differ significantly.
• Weight. Body weight fell 13.83% on retatrutide versus 0.05% on placebo.
• Serious adverse events. 9 of 73 people on retatrutide and 6 of 69 on placebo had a serious adverse event. No deaths were reported in either arm.

How to read it

A neutral result on measured GFR is not the same as harm. Weight-loss drugs often raise estimated GFR in short trials, and the Kidney Week abstract reports that creatinine- and cystatin C-based estimates did rise on retatrutide. The direct iohexol measurement did not move, which suggests at least part of that estimated gain reflects body composition rather than better filtration. The authors frame the flat measured GFR, together with lower albuminuria and blood pressure, as supporting “the potential for long-term kidney protection.” That is a hypothesis, not a finding of this trial.

The drop in kidney volume on MRI is a new detail. The registry does not explain it, and the abstract links retatrutide with less fat around and inside the kidney. Whether the volume change reflects fat, fluid or tissue is not stated.

What is not known

• Long-term outcomes. Twenty-four weeks cannot show whether retatrutide slows kidney decline, dialysis or kidney failure.
• Small analysis groups. The albumin finding comes from a subgroup of a few dozen people, and the measured-GFR analysis included 55 and 58 participants rather than all 146 randomized.
• Peer review. No full journal paper with these results was found as of publication.
• Next steps. Neither the registry record nor the abstract says whether Lilly plans a larger kidney outcomes trial.

This story summarizes a trial registry record and a meeting abstract. It is not medical advice.