Evaluation of vitamin B6 supplementation in Wilson's disease patients treated with D-penicillamine.

Introduction: Wilson's disease (WD) is a copper metabolism disorder characterised by a progressive accumulation of this metal mainly in the liver and the brain. Treatment is based on the removal of copper operated by the chelators, among which, D-penicillamine (DP) is prescribed as a first-line treatment in most situations. There is some evidence in linking the use of DP with a risk of vitamin B₆; therefore, vitamin supplementation is sometimes recommended, although non-consensually. The objective of our study was to evaluate the level of vitamin B₆ in WD patients treated with DP with and without associated supplementation.

Methodology: All WD patients followed at the National Reference Centre for WD in Lyon between January 2019 and December 2020 treated with DP for more than 1 year were included and separated in two groups according to vitamin B₆ supplementation. The level of vitamin B₆ was measured by the determination of pyridoxal phosphate (PLP).

Results: A total of 37 patients were included. Average age of 23.3±14.8 years, 15 patients with <18 years. Median duration of treatment was 51 (55.8) months. 15 patients were under vitamin B₆ supplementation and 22 had interrupted it for more than 1 year. The median PLP level was significantly higher in the group with supplementation, 137.2 (86.7) nmol/L vs 64.9 (30.8) nmol/(p<0.01). No patient had a PLP level<35 nmol/L.

Conclusion: Long-term stable WD patients under DP treatment probably do not need vitamin B₆ supplementation.