PTH levels correlate with mental performance in CAPD

Nervous system dysfunction remains a major cause of disability in patients with end stage renal disease. The mechanisms remain unclear, but elevated levels of parathyroid hormone (PTH) have been proposed to act as a neurotoxin in uremia. Previous studies have mainly used electroencephalographic techniques to assess mental performance in patients in dialysis. This study utilized the trail test A and the Pennsylvania bimanual dexterity work sample to evaluate mental performance of patients in CAPD and to correlate their performance with parathyroid hormone levels. Ten male patients from the same CAPD unit, with comparable dialysis dose, underwent standardized testing. Subjects had a mean +/- SE age of 50.8 +/- 3.66 years and had been on CAPD for a mean of 42.4 +/- 12.2 months. Each used 10-12 liters of dialysis per day, with a mean peritoneal dialysis index of 1.04 +/- 0.05 and Kt/V (UN/wk) of 2.35 +/- 0.39. Mental performance of patients with lower intact PTH levels 151.7 +/- 20.8 ng/ml (Group 1) was 34.4 +/- 2.8 min in the trail test A and patients with the higher PTH-mm level (414.0 +/- 21.4 ng/ml) was 58.2 +/- 10.8 min (p = 0.06). Whereas the bi-manual dexterity test was completed in 7.27 +/- 0.5 min by Group 1 and in 11.1 +/- 0.2 by Group 2 (p = 0.003). This study favors the hypothesis that PTH levels may be associated with the impaired mental performance observed in patients with end stage renal disease.