Blood Pressure Rises Observed in Living Kidney Donors

SAN FRANCISCO—Living kidney donors may experience an increase in systolic blood pressure (SBP) and may need closer monitoring for renal and cardiovascular (CV) abnormalities, researchers reported at the 28th Annual Scientific Meeting of the American Society of Hypertension.

“Elevations in blood pressure that are still ‘non-hypertensive' but in the currently defined pre-hypertension stage could be reflective of a latent risk for adverse cardio-metabolic outcomes in living kidney donors. Such individuals may benefit from closer monitoring,” said investigator George Thomas, MD, a staff physician at the Cleveland Clinic.

Dr. Thomas pointed out that living kidney donors make up a population that undergoes extensive evaluation prior to possible donation and is presumably healthy with no clinical diagnosis of hypertension, cardiovascular disease (CVD), or chronic kidney disease.

He and his colleagues studied 606 consecutive living kidney donors who underwent nephrectomy from April 1997 to November 2010. Of these, 88% were Caucasian and 59% were women. The mean age of the cohort was 41.3 years. Donors with a SBP 115-139 mm Hg or greater had a significantly greater number of potentially adverse cardiovascular (CV) and renal risk factors compared with the donors who had lower SBP. 

The study excluded donors if they had clinical hypertension (140/90 mm Hg), kidney disease, diabetes, CVD, obesity, and proteinuria. The investigators looked at age, gender, race, body mass index (BMI), office BP, fasting blood glucose, glucose tolerance, uric acid, lipid profile, and iothalamate glomerular filtration rates (iGFR).

The study population was stratified into SBP below 115 mm Hg and 115-139 mm Hg because clinical trials suggest an increased risk for CV events beginning with an SBP of 115 mm Hg.

Compared with donors with an SBP below 115 mm Hg, those with a SBP of 115-139 mm Hg had higher total cholesterol levels (201.8 vs. 192.6 mg/dL), higher LDL cholesterol levels (122.4 vs. 113.1 mg/dL), lower HDL cholesterol levels (54.2 vs. 57.1 mg/dL), higher triglyceride levels (123.1 vs. 106.3 mg/dL), and higher fasting blood glucose levels (89.6 vs. 85.9). The study also showed that uric acid (even within the normal range) was independently associated with elevated SBP.

“This study indicates early derangement and clustering of cardiovascular risk factors in living kidney donors, who are presumably healthy, with mild to modest increases in systolic blood pressure, even within what is considered per current definition to be within the non-hypertensive range,” Dr. Thomas said. “Elevated blood pressure even within the non-hypertensive range could thus be reflective of a latent risk for adverse cardio-metabolic outcomes in living kidney donors, the early recognition of which could support closer monitoring of such individuals for eventual cardiovascular abnormalities.”

Further studies are needed to see if instituting early interventions would improve their risk profile and prevent cardiovascular events, he said.                                                                          

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