Extreme potassium loss in a patient with severe graft versus host disease.

A 19-year-old male, suffering from post-hepatitis aplastic anaemia, was transplanted with bone marrow cells from his HLA-identical, MLC non-reactive brother. Haematological recovery ensued, but the patient also developed grade IV graft-versus-host disease (GVHD). In addition to involvement of skin, liver and gut, the kidney seemed affected by GVHD since the patient has hypokalaemia and severe hyperkaluria. Other causes of urinary potassium loss were excluded. The amount of potassium loss correlated well with the severity of the GVH-reaction. Although coagulation disorders prohibited a kidney biopsy, the clinical course suggested GVHD to be the cause of the urinary potassium loss.