Homocysteine elevation in sickle cell disease.

OBJECTIVE: Ischemic complications are common in patients with sickle cell disease. Hyperhomocysteinemia is a risk factor for arteriosclerosis and venous thrombosis, and given the propensity of patients with sickle cell disease to develop ischemic complications, we hypothesized that they might have elevated plasma homocysteine concentrations. METHODS: Plasma concentrations of homocysteine, vitamin B12 and folate were measured in 49 adults with sickle cell disease and 16 normotensive Black controls. All subjects with sickle cell disease had been prescribed folic acid 1 mg by mouth daily. RESULTS: The median plasma concentration of homocysteine of subjects with sickle cell disease was approximately 1.5-fold higher than that of controls (p=0.0008). This difference persisted, even when subjects with renal insufficiency were excluded. Plasma folate levels were 1.5-fold higher in subjects with sickle cell disease than in controls (p=0.0498). There was no significant difference in plasma vitamin B12 concentrations between the two groups. There was no difference in plasma homocysteine concentrations between transfused and non-transfused sickle cell subjects. CONCLUSIONS: Patients with sickle cell disease have elevated plasma concentrations of homocysteine in spite of elevated plasma folate levels and vitamin B12 concentrations similar to those observed in controls. Based on these data, we hypothesize that the concentration of folate required to normalize plasma homocysteine levels in patients with sickle cell disease may be higher than that of normal controls and that patients with sickle cell disease have a higher nutritional requirement for folic acid than the general population.

Retinopathy secondary to anemia from myeloid metaplasia in polycythemia vera.

BACKGROUND: Polycythemia vera is a chronic clonal disorder associated with excessive proliferation of erythrocytes, leukocytes, and thrombocytes, as well as an accompanying splenomegaly. Ocular manifestations of polycythemia vera include occipital cortex transient ischemic attacks, transient monocular blindness, vaso-occlusive disease, and retinal hemorrhages. CASE REPORT: A 56-year old man with longstanding polycythemia vera sought treatment for a chief symptom of blurred vision in the left eye and a red tinge to things first noticed on awakening that morning. He had preretinal and intraretinal hemorrhages and was subsequently found to be severely anemic as a result of postpolycythemic myeloid metaplasia after years of phlebotomy. Splenectomy controlled his anemia and thrombocytopenia, allowing transient improvement of the retinal hemorrhages. Acute leukemia subsequently developed and the patient died 7 weeks after initial examination. CONCLUSION: In this case, preretinal and intraretinal hemorrhages were found in a patient with longstanding polycythemia vera. The exact origin of these hemorrhages is uncertain. They are probably secondary to anemia, but the possibility that they are sites of extramedullary hematopoiesis must be considered. The appearance of retinal hemorrhages warrants careful investigation to rule out diabetes, hypertension, and anemia, as well as the various other blood dyscrasias.

Sickle cell acute chest syndrome associated with parvovirus B19 infection: case series and review.

Acute Chest Syndrome (ACS) continues to be a major source of morbidity and mortality among patients with sickle cell disease. It is characterized by the presence of pleuritic chest pain, fever, raises on lung auscultation, and pulmonary infiltrates on chest x-ray [Castro et all: Blood 84:643-649]. The pathophysiology of this disorder remains poorly understood leading to the descriptive term "Acute Chest Syndrome" designated by Charache et al. [Arch Intern Med 139:67-69, 1979]. Typical bacterial pathogens are seldom isolated in adults, although they play a significant role in the pathogenesis of this entity in children. Until recently, the technology to accurately study viral infection as a precipitating cause of ACS has been unavailable. Parvovirus B19 is being increasingly recognized as an important human pathogen, and has been established as the cause of transient "aplastic crisis" in patients with sickle cell diseases [Saarien et al: Blood 67:-11411-11417, 1986; Young: Sem Hematol 25:159-172, 1988]. We present three patients with hemoglobin SC variant of sickle cell disease who developed ACS in association with acute parvovirus B19 infection, one of which died of respiratory failure. Parvovirus B19 infection was established by polymerase chain reaction for parvovirus B19 DNA, and the presence of parvovirus B19 specific IgM antibodies. These cases suggest that parvovirus B19 may be associated with more than self-limited illness in patients with sickle cell disease, and that this ubiquitous virus may merit further study as a precipitating cause of ACS.