Cihan Uysal, Tugba Yilmaz, Merve Civan, Mehmet Fatih Yetkin, Cigdem Karakukcu, Gizem Kursunluoglu, Gokmen Zararsiz, Ismail Kocyigit
Experimental and Clinical Transplantation - 2025;23(12):787-795
Objectives : Tacrolimus-induced tremors were evaluated in relation to plasma pyridoxine status among kidney transplant recipients. Materials and Methods: Eligible patients were at least 6 months posttransplant with a functioning allograft, with the last 3 tacrolimus trough levels within target range. We analyzed 20 healthy volunteers solely for vitamin B6 status. Vitamin B6 insufficiency was defined as a pyridoxal-5 ?-phosphate level <7.5 mug/L (30 nmol/L). The tremor was detected by clinical examination and scored with the Essential Tremor Rating Assessment Scale. Results: We included 77 kidney transplant recipients (45.0 +/- 12.4 years). Mean estimated glomerular filtration rate was 63.2 +/- 22.0 mL/min/1.73 m 2. Mean tacrolimus trough level was 6.4 +/- 2.0 ng/mL. Average pyridoxal-5 ?-phosphate level was 8.3 mug/L (IQR 6.6-10.0 mug/L) in kidney transplant recipients and 13.3 mug/L (IQR 11.4-16.9 mug/L) in healthy volunteers (P < .001). Vitamin B6 insufficiency was identified in 27 kidney transplant recipients (35.0%), whereas no cases were observed in volunteers. Tremor was observed in 45 kidney transplant recipients (58.4%). Tacrolimus trough levels did not significantly differ between patients with and without tremors. The pyridoxal-5 ?-phosphate level was 7.7 mug/L (IQR 6.3-9.2 mug/L) in recipients with tremors versus 9.0 mug/L (IQR 7.7-10.4 mug/L) in those without tremors ( P = .035). Tremor frequency was significantly higher in recipients with vitamin B6 insufficiency versus those with sufficient vitamin B6 levels (77.8% vs 48.0%; P = .010). The Essential Tremor Rating Assessment Scale scores were not correlated with tacrolimus levels ( P = .733) and pyridoxine concentrations ( P = .322). Multivariate logistic regression analysis revealed that vitamin B6 insufficiency was an independent predictor for presence of tremor ( P = .047). Vitamin B6 insufficiency was also associated with poorer outcomes in nerve conduction studies. Conclusions: Plasma pyridoxine was lower in kidney transplant recipients. Vitamin B6 insufficiency may be a facilitating factor for tacrolimus-induced tremors.
