Congenital erythrocytosis in the absence of detectable erythropoietin

Abstract

IN CHILDREN erythrocytosis or polycythemia is most commonly a response to chronic arterial hypoxemia. Rarely, polycythemia is a primary congenital defect which in some instances may be familial? Such cases may be caused by high-affinity hemoglobin mutants or by unexplained erythropoietin overproduction in the absence of an identifiable cause of hypoxia. ~, 2 Recently there have been several reports of adults with a polycythemia vera-like disorder in which erythropoiesis appears to be autonomous or totally independent of erythropoietin. 3 We now describe a similar patient, a 9-year-ofd girl with congenital erythrocytosis, without detectable erythropoietin in her serum. CASE REPORT The patient had a hemoglobin concentration Of 14.9 gm/dl at 3 months of age. She was in good health throughout infancy and early childhood, and never required hospitalization. At 7 years of age she had a blood count done at the time of an upper respiratory infection and was found to have a hemoglobin of 18.7 gm/dl and hematocrit of 58%. She was referred to our institution for evaluation at 9 years of age. Careful review of symptoms was unremarkable except for fatigue and slight dyspnea with exertion during the previous two years. The family history was entirely negative for hematologic disorders. Consanguinity was not present and there were no siblings. The patient's father died of a myocardial infarct at age 42 years. Prior to his death he was documented to have a hemoglobin of 15.0 gm/dl and hematocrit of 45%. The patient's mother was in good health and fiad normal hemoglobin and hematocrit values. The physical examination was entirely within ~normal limits except for moderate plethora and a barely palpable spleen tip. Routine hematologic studies included multiple hematocrit determinations between 55 and 62% and hemoglobin measurements between 19 and 22 gm/dl. Reticulocyte counts ranged between 0.5 and 2.0%. The mean corpuscular volume was 82 ft. Her total and differential white blood cell counts and platelet counts were always normal. The following diagnostic laboratory studies were normal or negative: chest radiograph, intravenous pyelogram, pulmonary function tests, electrocardiogram, arterial blood gas values in room air and in 100% oxygen, hemoglobin electrophoresis on cellulose acetate (pH 8.6) and citrate agar (pH 6.3), fetal hemoglobin by the alkali denaturation method, serum iron and