A possible case of carbamazepine-induced renal phospholipidosis mimicking Fabry disease.

Abstract

Fabry disease (FD) is a genetic disorder caused by a-galactosidase A gene mutation. Ultrastructural analysis revealing zebra bodies are the typical morphological characteristics. However, certain tricyclic antidepressants and some other medications could induce renal phospholipidosis mimicking FD. We report a 33-year-old man has been taking carbamazepine intermittently for around 10 years whenever he experiences pain and paresthesia in his fingers. He experienced mild edema on both lower limbs half a year ago. Laboratory tests revealed a fluctuating urine protein between + and ++. Electron microscopy revealed laminated "zebra body" in podocytes, which is typical of FD. However, the patient had no family history and the sequencing of the a-galactosidase gene revealed no mutations. The a-galactosidase A enzyme activity was normal at 6.03μmol/mL/h (normal 2.40-17.65μmol/mL/h), and low expression of globotriaosylceramide (Gb3) was detected in the renal tissue of this patient. Therefore, the diagnosis of Fabry disease was excluded. Considering the patient's long-term treatment with carbamazepine (blood level 1.8μg/ml), we speculated whether the pathological features could be associated with renal phospholipidosis caused by carbamazepine. The follow-up data showed that proteinuria was improved (fluctuated at + ~ -) after discontinuing carbamazepine for six months, which further seemed to support the above diagnosis. Therefore, we concluded that a possible case of carbamazepine-induced renal phospholipidosis, mimicking that observed in FD, has been associated with its nephrotoxicity.