Cuevas-Ramos and his colleagues studied 140 adults who donated a kidney. Of those, 28 donors had the metabolic syndrome before donation and 112 did not. Using long-term follow-up data, the investigators determined each donor's kidney function after donation, measured by the glomerular filtration rate, or GFR, on a blood test. In general, a GFR below 70 milliliters per minute indicates below-normal kidney function.

The average time it took for donors' GFR to drop below 70 was less than six years in those who had the metabolic syndrome before donation versus approximately 13 years in donors without the syndrome.

"This study does not suggest that the metabolic syndrome is a contraindication for kidney donation but rather another potential risk factor for decline in renal function," Cuevas-Ramos said.

Medical reasons for rejecting a kidney donor, called contraindications, vary among U.S. transplant centers. However, diabetes, obesity, and high blood pressure are usually contraindications to donating a kidney.

Source: The Endocrine Society