Calcineurin inhibition with tacrolimus has been used after renal transplantation (RTPL) as rescue therapy for insufficient immunological control or if cyclosporin A (CSA) toxicity occurred. Neurologic side-effects occur but are rare in children, usually presenting as tremor; however, serious complications, e.g. the posterior leukoencephalopathy syndrome are also documented. Twenty children (10 girls) were switched to tacrolimus: 11 (55%) for immunological reasons (n = 9: steroid-resistant rejection; n = 2: recurrent rejections) and nine for CSA side-effects. Tacrolimus was started at a median of 8 wk (range 10 d to 8.7 yr) after RTPL and was continued for a median of 2.5 yr (range 5 wk to 4.6 yr). Renal function significantly improved over a period of 12 months following conversion to tacrolimus (glomerular filtration rate 56 +/- 19 vs. 66 +/- 16 mL/min/1.73 m2; p < 0.03; n = 13). Fifteen of 20 (75%) patients tolerated tacrolimus well. The most frequent side-effects were neuropsychological and behavioral symptoms in three children, ranging from anorexia nervosa-like symptoms with weight loss, amenorrhea, depression and school problems to severe insomnia and to aggressive and anxious behavior in one child. Only the latter child was exposed to toxic tacrolimus blood levels. All side-effects were fully reversible after discontinuation of tacrolimus. In conclusion, tacrolimus had a beneficial effect on renal function and was well tolerated in the majority of pediatric patients. However, neuropsychologic and behavioral side-effects are important and maybe underrecognized in children.
