The Influence of Physical Activity on Serum Phosphate Levels in a Group of Hemodialysis Patients

The prevalence of mineral bone disorders in chronic kidney disease (MBD-CKD) and the cardiovascular risk are increased in hemodialysis (HD) patients. Hyperphosphatemia is one of the complications often associated with increased cardiovascular risk, and in CKD patients, the reduced renal excretion of phosphate is an important cause of elevated serum of this microelement. Physical activity represents another contributing factor in evaluating the risk of cardiovascular disease. The aim of our study was to determine the influence of physical activity on serum phosphate levels in HD patients. The inclusion criteria of this 3-months study were: age > 18 years old, dialysis vintage > 6-months, diuresis > 500 mL/day, PTH values between 100500 pg/mL, similar dialysis protocol, phosphate daily intake and MBD-CKD therapy. The following parameters were monitored: dry weight, diuresis, associated comorbidities, hemoglobin, serum calcium, phosphate, sodium, potassium, serum albumin, intact parathormon, bicarbonate. The physical activity was assessed during 4 days (3 week-days and 1 during the week-end) for 3 months, and the patients had to complete a questionnaire, too. 49 patients were included and divided in 5 groups, depending on their physical activity. Analyzing the parameters influence on serum phosphate levels, we observed that physical activity, serum calcium and albumin were the only parameters statistically significant (p = 0.001, p = 0.033, and p = 0.47, respectively). The nutritional recommendations of chronic HD patients should be adapted to their individual level of physical activity, in order to avoid an abnormal increase of serum phosphate level, and to improve to over-all outcome.