WEB DESK: Even slightly impaired kidney function can cause subtle damage to the heart and blood vessels, and patients should talk to their doctors about how to reduce heart disease risk, according to a new study.
Most people with kidney problems have other conditions like high blood pressure and diabetes, so it has been difficult to tell if kidney problems actually increase heart risk, according to senior author Dr. Jonathan Townend of the Queen Elizabeth Hospital Birmingham in Edgbaston, UK.
The new study was done in healthy people who had chosen to donate a kidney to a patient needing a kidney transplant.
In these healthy donors, who go from having normal kidney function to slightly impaired kidney function, subtle abnormalities “occur quite quickly,” Townend told Reuters Health by email.
For one year, the researchers tracked 68 kidney donors and 56 similar adults who had not donated a kidney.
The transplants were done between 2011 and 2014. During the following year, based on levels of protein in urine, kidney function did decline slightly for the donors. In addition, based on magnetic resonance imaging, the left ventricle of the heart grew noticeably in kidney donors and blood tests revealed some heart damage.
Blood pressure did not change in either group, the authors report in a paper scheduled for publication in the journal Hypertension.
However, a statistically significant finding of changes in cardiovascular structure and function does not necessarily mean that patients would notice the difference, said professor Vivekanand Jha of the George Institute for Global Health in New Delhi, India, who was not part of the new study.
The abnormalities detected in this study would not require treatment, he said.
“The clinical significance of these findings needs to be determined on long term studies by following up these individuals to see whether they develop any significant cardiovascular ‘disease,’” Jha told Reuters Health by email. “Until then these findings indicate need for observation but (are) not of definitive clinical importance.”
“We don’t fully understand the mediators that cause the heart and blood vessel damage in people with kidney problems,” said Townend. “It may be a complex mix of factors such as low grade inflammation, oxidative stress and activation of . . . blood pressure regulating compounds (in the blood) such as renin and angiotensin.”
Severe kidney disease is rare, but as much as 13 percent of the U.S. population has some degree of reduced kidney function, he said.
“For most people with reduced kidney function there are no signs or symptoms,” he said. “It is diagnosed on simple blood and urine tests.”
People who know they have reduced kidney function should talk to their doctor about preventing heart disease, which now centers around careful blood pressure control, he said.
Kidney donors, however, should not be worried about these results.
“Kidney donation is only considered in very healthy subjects who are at extremely low risk of cardiovascular risk,” Townend said. “Even if long term cardiovascular risk is increased a little in donors, their absolute risk of cardiovascular disease probably remains lower than that of the general population.”
“I do not think our results so far should deter anybody from considering kidney donation,” he said. “It enables a fantastic life prolonging treatment for the recipient at only minimal risk to the donor.”