Valproïnezuurintoxicatie door misinterpretatie van plasmaspiegel: Verhoogde ongebonden fractie door hypoalbuminemie en nierfunctiestoornis

CASE DESCRIPTION: A 65-year-old male with a type 1 bipolar disorder developed a number of neurological symptoms including sluggishness, muscle weakness, difficulty in walking and disorders of micturition after his mood stabiliser was changed to valproic acid. Recognition of drug toxicity was delayed as his total plasma valproic acid levels were within the therapeutic range. Later it became apparent that the patient had toxic unbound valproic acid levels due to hypoalbuminaemia and impaired renal function.