Nephrotic syndrome associated with hypocomplementemia in a 4-year-old boy with hemophilia B

The case of a 4-year-old boy with hemophilia B with inhibitor who developed nephrotic syndrome is described. The possible association between factor IX therapy and nephrotic syndrome in patients with hemophilia B is discussed.

A chart review of a 4-year-old boy with hemophilia B and an inhibitor who developed nephrotic syndrome with transient hypocomplementemia was performed. In addition, a literature search was undertaken to determine the prevalence of this association and possible etiologic factors.

Although the nephrotic syndrome was resistant to steroid therapy and Bebulin (Osterreichisches Institut für Haemoderivate Ges.M.B.H., Subsidiary of Immuno AG, Vienna, Austria) infusions were continued, the edema resolved and proteinuria decreased. Seven month later, proteinuria, accompanied by transient hypocomplementemia, increased again. A rise in factor IX inhibitor level was observed. The patient received no immunosuppressive therapy, and exhibited a continuous decrease in urinary protein excretion over the following months.

A discussion about possible differential diagnoses and a review of the literature are presented.