Middle-aged, older men face greater kidney function decline than women in aging
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In middle-aged women, kidney function declined slower than it did in men the same age or older during aging, according to a study in the Journal of the American Society of Nephrology.
Further, a lack of major chronic diseases or risk factors for chronic kidney disease did not explain the difference in kidney decline observed between sexes, according to researchers.
“Because the common method to estimate kidney function using creatinine levels in the blood is inaccurate and unreliable, we measured the kidney function by intravenous injection of a kidney filtration marker — the contrast media iohexol,” Toralf Melsom, MD, PhD, from the section of nephrology at University Hospital of North Norway in Tromsø, Norway, said in a press release. “A blood sample was collected 3 [to] 4 hours later to calculate the kidney filtration rate. This method has been regarded as too complicated to use in population-based studies; however, during 11 years of follow-up, we performed more than 4,000 kidney function measurements in 1,837 people.”
In a population-based study in northern Europe, Melsom and colleagues evaluated 1,837 participants, including women aged 50 to 62 years and men aged 50 to 75 years, to observe the role sex differences play in age-related kidney function loss and whether there are sex disparities in glomerular filtration rate (GFR) decline rates according to health status. Participants reported no diabetes, CKD or cardiovascular disease.
Timeline, characterization
Researchers used the Renal lohexol Clearance Survey to observe age- and sex-specific GFR decline rates, which was the outcome of interest for the study. Repeated measurements of GFR were obtained, and there were 1,627 measurements of GFR by plasma iohexol clearance taken in 2007 to 2009; 1,324 in 2013 to 2015; and 1,384 in 2018 to 2020. A random sample of 210 participants who were invited in the first group but were not studied were also included.
Researchers defined a healthy individual “as a non-smoking person with no diabetes or hypertension, BMI [less than] 30 kg/m2, [American College of Rheumatology] ACR [less than] 3.4 mg/mmol (30 mg/g), and without self-reported previous myocardial infarction, angina pectoris, coronary revascularization procedure, stroke, cancer or use of lipid-lowering medication or cardiac glycosides” to determine if health status explained differences in GFR decline.
GFR rates
Mean age of participants was 58 years, and 53% were women. Median follow-up was 10.7 years for participants with measurements taken between 2007 and 2009.
At baseline, women were observed to have a lower GFR compared with men (90 mL/min per 1.73 m2 vs. 98 mL/min per 1.73 m2).
However, in women, the mean GFR change rate was –0.96 mL/min per 1.73 m2 per year, whereas in men, there was 25% steeper mean decline as they aged, according to the study.
In women, age and GFR were almost linear; in men, the relationship was curvilinear and had steeper GFR slopes at older ages.
Compared with healthy participants, researchers observed a rapid GFR decline of 0.28 mL/min/1.73 m2 per year in participants who were “not healthy”.
Although individuals classified as healthy had a slower GFR decline compared with those who were “not healthy,” the sex difference in the GFR decline could not be explained by health status because the change rate was comparable to the one found in the model that did not include this factor, according to the researchers.
“This study is the first study that repeats accurate measurements of kidney function in relatively healthy women and men during aging,” Melsom said in the release. “By doing so, we provide important knowledge regarding age-related loss of kidney function and sex disparities in the prevalence of CKD. The study may in part explain why more women are diagnosed with early CKD and more men develop severe CKD and kidney failure during aging. Accelerated loss of kidney function has been associated with premature death in previous studies. The role of age-related loss of kidney function on healthy aging and life expectancy in women and men should be addressed in further studies.”
Reference:
- Study reveals sex differences in age-related loss of kidney function. https://www.asn-online.org/about/press/releases/ASN_PR_20220817_JASN.MelsomFinalAug.pdf. Published Aug. 17, 2022. Accessed Aug. 31, 2022.
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