PNPO and hyperinsulinemic hypoglycemia, familial, 4: While this study used levels of B6 vitamers to guide PLP dosing post‐transplant, the so‐far unique situation of having a patient with PNPO deficiency with normal hepatic PNPO activity means that the B6 vitamer levels we measured are unlikely to reflect those seen in patients with PNPO deficiency who have not undergone liver transplantation.