Use of carnitine therapy in selected cases of male factor infertility: a double-blind crossover trial.

Objective: To determine the efficacy of L-carnitine therapy in selected cases of male factor infertility.

Design: Placebo-controlled, double-blind, crossover trial.

Setting: University tertiary referral center.

Patient(s): One hundred infertile patients (ages 20-40 years) with the following baseline sperm selection criteria: concentration, 10-20 x 10(6)/mL; total motility, 10%-30%; forward motility, <15%; atypical forms, <70%; velocity, 10-30 micro/s; linearity, <4. Eighty-six patients completed the study.

Intervention(s): Patients underwent L-carnitine therapy 2 g/day or placebo; the study design was 2 months of washout, 2 months of therapy/placebo, 2 months of washout, and 2 months placebo/therapy.

Main Outcome Measure(s): Variation in sperm parameters used in the patients selection criteria, in particular, sperm motility. Excluding outliers, a statistically significant improvement in semen quality, greater than after the placebo cycle, was seen after the L-carnitine therapy for sperm concentration and total and forward sperm motility. The increase in forward sperm motility was more significant in those patients with lower initial values, i.e., <5 x 10(6) or <2 x 10(6) of forward motile sperm/ejaculate or sperm/mL.

Conclusion(s): Based on a controlled study of efficacy, L-carnitine therapy was effective in increasing semen quality, especially in groups with lower baseline levels. However, these results need to be confirmed by larger clinical trials and in vitro studies.