[A rare cause of anemia in a kidney-transplant recipient]

Anemia is a phenomenon frequently observed after kidney transplantation and differential diagnosis is broad.

A 39-year-old woman who had been transplanted a kidney of her father 11 months ago was admitted to the hospital because of severe and worsening anemia (hematocrit [Hct] 0.24). She was under a standard posttransplant immunosuppressive protocol consisting of tacrolimus, mycophenolate mofetil (MMF) and prednisolone. Kidney function was excellent (serum creatinine 118 micromol/l), clinical symptoms of anemia included vertigo, fatigue and low blood pressure. Striking laboratory features were reticulocytopenia (1 per thousand), high ferritin (3,486 microg/l) and low folic acid (4.8 nmol/l), other parameters remained in the normal or therapeutic range. Endoscopic examinations did not reveal any pathologic finding. Bone marrow biopsy, however, showed giant pronormoblasts and the missing of more mature forms as a possible hint to a lack of, e. g., vitamin B(12) (whose serum level was normal, though). After all, the most probable cause of the anemia seemed to be a toxic drug effect and MMF as a possible causative agent was significantly reduced. Nonetheless, the red blood cell count continued to fall (lowest Hct 0.18). On a later outpatient visit all of a sudden positive IgM and IgG antibodies against parvovirus B19 could be detected. Due to a high virus load short-term immunoglobulin treatment was instituted, after which Hct levels rose to normal and virus load decreased to a low degree although still detectable.

An infection with parvovirus B19 should always be taken into account as a possible cause of anemia in immunosuppressed patients. Establishing the diagnosis in the acute stage of the disease can be difficult, as antibodies are often negative in these patients and viremia remains the only proof. In most cases a substantial reduction of immunosuppressive therapy is necessary, the infection's relevance for the development of a potentially life-threatening myocarditis is still a matter of debate.