A 50-year-old man with end-stage renal disease secondary to long-standing hypertension had an elevated hematocrit and progressively increasing hemoglobin levels. For the past 7 years, he had been receiving hemodialysis 3 times a week. He denied headache, flushing, easy bruising, bleeding, nausea, vomiting, chest pain, dyspnea, and other symptoms. He was not receiving exogenous erythropoietin.
History. The patient had had a positive result on a tuberculin skin test about 10 years earlier and received appropriate prophylaxis. He had undergone arteriovenous (AV) fistula placement in 1999 and back surgery and an appendectomy in the 1980s. His medications included hydralazine, 75 mg every 6 hours; amlodipine, 10 mg qd; calcium carbonate, 1000 tid; and metoprolol, 50 mg bid. He had no drug allergies; however, aspirin and warfarin had caused upper GI bleeding. His mother and sister both died of breast cancer, but he had no family history of kidney disease or blood dyscrasia. He had smoked 1 pack of cigarettes a day for 35 years; he denied use of alcohol or illicit drugs.
Physical examination. The patient weighed 107.4 kg (263.3 lb). Heart rate was 97 beats per minute; blood pressure, 85/64 mm Hg; and oxygen saturation, 96% on room air. Pupils were reactive bilaterally with pink conjunctiva. Mucous membranes were moist. There was no jugular venous distention, and his heartbeat was regular, with no murmurs. Lungs were clear. Abdomen was soft and nontender. No abdominal or flank masses were found. An AV fistula was noted in the left upper extremity; there was no edema in the lower extremities.
Laboratory results. White blood cell count was 8300/µL; hemoglobin level, 16.5 g/dL with hematocrit, 48.6%; and platelet count, 202,000/µL. Results of a chemistry panel included the following levels: blood urea nitrogen, 45 mg/dL; creatinine, 10.3 mg/dL; calcium, 7.7 mg/dL; albumin, 4.6 g/dL; total protein, 9.9 g/dL; alkaline phosphatase, 393 U/L; alanine aminotransferase, 16 U/L; and aspartate aminotransferase, 66 U/L.
Plasma erythropoietin level was elevated at 40.5 mU/mL. Reticulocyte count was 2.5%, with an iron level of 47 µg/dL, a total iron-binding capacity of 275 µg/dL, and a saturation iron binding capacity of 17%.
Carboxyhemoglobin level was 3.5%. Results of pulmonary function tests were otherwise normal.
Imaging studies. A report of an MRI scan of the patient's abdomen performed in 2002 described numerous hemorrhagic and nonhemorrhagic renal cysts bilaterally. The largest of these, on the right kidney, measured 3.5 cm in diameter.
A recent (2006) MRI scan of the abdomen showed numerous well-defined intraparenchymal and exophytic cysts scattered diffusely throughout both kidneys (Figures 1 and 2). The largest, in the mid-pole of the anterior right kidney, measured 2.9 x 2.8 x 2.9 cm. Compared with the 2002 study, the number of cystic lesions had increased markedly; very little renal parenchyma was visible. Some of these cysts were hemorrhagic; none showed abnormal enhancement.
ERYTHROCYTOSIS: AN OVERVIEW
Erythrocytosis, or polycythemia, is characterized by an elevated red blood cell mass. It may result from increased proliferation of erythrocyte progenitors or from abnormal erythrocyte regulation. Clinically, it usually manifests as hemoglobin levels above 17.7 g/dL in men or 15.7 g/dL in women and a hematocrit greater than 51% in men or 48% in women. Symptoms of the hyperviscosity characteristic of erythrocytosis may include headache, dizziness, light-headedness, a congested sensation, and worsening of exercise tolerance.1 Include in the workup determination of serum erythropoietin level, measurement of red cell mass and plasma volume, and determination of oxygen saturation.2
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