Relationship between vitamin D and muscle size and strength in patients on hemodialysis.

OBJECTIVE

Vitamin D has various actions in skeletal muscle. The purpose of this study was to compare lower-limb muscle size and strength in hemodialysis (HD) patients being treated with 1,25-dihydroxyvitamin D (calcitriol) or a 1,25-dihydroxyvitamin D analogue (paricalcitol) with lower-limb muscle size and strength in HD patients who were receiving none.

DESIGN

This was a retrospective, cross-sectional study.

SETTING

This study was performed in outpatient HD centers.

PATIENTS: Hemodialysis patients receiving calcitriol or paricalcitol (active vitamin D) for control of secondary hyperparathyroidism (VitD, n = 49) were compared with HD patients who were not (n = 30).

MAIN OUTCOME MEASURES: The main outcome measures included the cross-sectional areas (CSAs) of the thigh and tibialis anterior muscles by magnetic resonance imaging, and three measures of strength: the three-repetition maximum (3RM) for knee extension (isotonic), the peak torque of knee extensors (isokinetic), and maximal voluntary contraction of the ankle dorsiflexor muscles (isometric).

RESULTS

There were no differences in age, weight, dialysis vintage, or intact parathyroid hormone levels between groups, although serum albumin was higher in the VitD group (P < .05). Patients in the VitD group had a larger thigh-muscle CSA (P < .05) and were stronger across all strength measures (P < .05) after controlling for age and gender (by analysis of covariance). When all analyses were subsequently adjusted for serum albumin concentration, only the difference in 3RM knee-extension strength lost significance. There were no significant differences in any measurements between patients who received calcitriol or paricalcitol.

CONCLUSION

Treatment with active vitamin D was associated with greater muscle size and strength in this cohort of HD patients.