A study from 250 Chinese Renal Transplant Centers in the US shows that patients undergoing kidney transplants in areas with the highest fever index show a percentage of renal decline and major renal events (MAKE) compared to recipients of transplants performed in cool environments.
“In US kidney transplant recipients, higher heat exposure was independently associated with a gradual progressive decline in kidney transplant function and was associated with an increased risk compared to a lower fever exposure,” reported first author Gabriel Konigsberg, MD, Beth Israel Deacones Medical Center, Boston, National Kidney Foundation (NKF) at Spring 2025 clinical conference.
“Preventing heat exposure to kidney transplant recipients should gain a higher priority in research, public health initiatives and clinical practice to prevent the harmful consequences of kidney transplants,” he said.
Surrounding fever exposure is associated with worsening kidney outcomes in a variety of situations, including the potential to exacerbate existing chronic kidney disease (CKD), causing acute kidney damage and increasing the risk of episodes of kidney stones, Cojuc-Konigsberg said.
Additional research shows that agricultural workers in tropical and subtropical regions are disproportionately affected by CKD, and that these concerns are strengthened under the threat of climate change.
“The exact mechanism of this connection remains unknown, but rising global temperatures pose a major threat to kidney health,” Kojuk Konigsberg said.
To further explore the role of heat exposure among kidney transplant recipients, Cojuc-Konigsberg and colleagues retrospectively reviewed 63,351 kidney transplant recipients identified in the UNOS-STAR cohort who were transplanted between 2010 and 2023 and had at least two serum Creatinine measurements within a year.
The average age of the patients was about 53 years old, with about 39% being female. Approximately 53% of most patients were treated with tacrolimus.
The 250 kidney transplant centers under study were classified as high temperatures, at least 12 months, with a heat index of at least 30°C during the study period, cold, and colder than 12 months with a heat index of at least 30°C. The thermal index for this study was calculated based on perceived heat, including factors such as humidity and ambient drying temperature.
Overall, 58 centers (23%) treated with 14,901 (23%) of transplant recipients were classified as hot.
Median follow-up was 4.9 years and four serum creatinine measurements, and was associated with an average annual decline of −0.62% for each additional year with an average heat index of at least 30°C after multivariate adjustment.
Furthermore, kidney transplant recipients transplanted in a high temperature setting have a 30% increase in manufacturer risk, with a double increase in death, graft disorders, or serum creatinine due to any cause compared to kidney transplant recipients at cold centers (compared with adjusted hazard ratios). [aHR]1.30; p <.001).
“Our main analysis observed that increased heat exposure was associated with progressive and faster reductions in EGFR,” Cojuc-Konigsberg said.
No differences were observed based on donor type (live or dead) or the use of tacrolimus at discharge, but those with a lower baseline EGFR showed a faster reduction in EGFR associated with heat exposure.
“Overall, we found that for individuals exposed to heat exposure, every additional year with a heat index above 30°C, there is a 30% higher risk of major adverse kidney events defined as death, graph impairment, or double serum creatinine,” Cojuc-Konigsberg said.
A risk factor for amount depletion, immunological status?
Commenting on the study, Samira Farouk, an associate professor of medicine and medical education at Ikaan School of Medicine in New York City, noted that a variety of factors could play a role in the effects of heat exposure to the kidneys.
“First of all, we know that depletion of the volume in which a person is dehydrated is associated with acute kidney damage, and that uric acid levels associated with heat exposure can cause kidney damage over time,” she said. Medscape Medical News.
“Secondary factors could include access to clean water in some hot environments,” she added. Additionally, hot climates can predispose to certain infectious diseases, such as mosquito-borne diseases.
Another consideration, particularly with regard to kidney transplant recipients, is the role of heat exposure in people at immune risk.
“I know that other environmental exposures can affect T-cell activation and behavior, such as diet, air pollutants, microorganisms that someone is exposed to, so I think there is a possibility that heat exposure can also occur in this,” Farouk said.
“We don't actually have a good way to know someone is immunosuppressed, so it would be interesting to understand whether being in a hotter climate will affect your immune system,” she said.
Farouk noted that encouraging kidney transplant recipients to maintain hydration is already an important challenge, but the new findings underscore the importance of doing so.
“It is very important for kidney transplant recipients to try to drink water and maintain their volume. This can be a challenge for those undergoing a transplant because if they've been on dialysis for many years they're told not to drink many drinks, then they'll make more urine, and then they'll be told to drink more water,” she said.
“So if you add to it to the hot climate, I can imagine it [staying hydrated] This is especially important with this data. ”
Cojuc-Konigsberg and Farouk had no disclosure to report.
