Clinical implications of sickle-cell trait and glucose-6-phosphate dehydrogenase deficiency in hospitalized black male patients

Sickle Cell Trait, Heroic Exercise, and Fatal Collapse

In brief Although sickle cell trait is generally benign and consistent with peak athleticism, it poses a small risk of gross hematuria and splenic infarction at altitude. More alarming is the growing evidence that, in some people with sickle cell trait, maximal exercise-especially in hot weather or when new at altitude-can evoke a life-threatening syndrome of sickling, fulminant rhabdomyolysis, lactic acidosis, collapse, acute renal failure, and hyperkalemia. More than 30 such cases are described, along with practical tips for recognition and prevention.

Case report: sickle cell trait and recurrent deep venous thrombosis

Thromboembolic events are unusual in patients with sickle cell trait, particularly in the absence of hypoxic stresses. A young black man with multiple episodes of lower extremity deep venous thrombosis, the first of which occurred when he was 18 years old, is reported. The only identifiable risk factor for recurrent venous thrombosis was the presence of sickle cell trait.

Effects of alpha-thalassemia and sickle polymerization tendency on the urine-concentrating defect of individuals with sickle cell trait

A defect in urine concentrating ability occurs in individuals with sickle cell trait (HbAS). This may result from intracellular polymerization of sickle hemoglobin (HbS) in erythrocytes, leading to microvascular occlusion, in the vasa recta of the renal medulla. To test the hypothesis that the severity of the concentrating defect is related to the percentage of sickle hemoglobin present in erythrocytes, urinary concentrating ability was examined after overnight water deprivation, and intranasal desmopressin acetate (dDAVP) in 27 individuals with HbAS. The HbAS individuals were separated into those who had a normal alpha-globin genotype (alpha alpha/alpha alpha), and those who were either heterozygous (-alpha/alpha alpha) or homozygous (-alpha/-alpha) for gene-deletion alpha-thalassemia, because alpha-thalassemia modulates the HbS concentration in HbAS. The urinary concentrating ability was less in the alpha alpha/alpha alpha genotype than in the -alpha/alpha alpha or -alpha/-alpha genotypes (P less than 0.05). After dDAVP, the urine osmolality was greater in patients with the -alpha/-alpha genotype than with the -alpha/alpha alpha genotype (882 +/- 37 vs. 672 +/- 38 mOsm/kg H2O) (P less than 0.05); patients with the -alpha/alpha alpha genotype had greater concentrating ability than individuals with a normal alpha-globin gene arrangement. There was an inverse linear correlation between urinary osmolality after dDAVP and the percentage HbS in all patients studied (r = -0.654; P less than 0.05). A linear correlation also existed for urine concentrating ability and the calculated polymerization tendencies for an oxygen saturation of 0.4 and O (r = -0.62 and 0.69, respectively). We conclude that the severity of hyposthenuria in HbAS is heterogeneous. It is determined by the amount of HbS polymer, that in turn is dependent upon the percentage HbS, which is itself related to the alpha-globin genotype.

Pulmonary embolism and splenic infarction in a patient with sickle cell trait

A 43 year-old black man with sickle cell trait documented by hemoglobin electrophoresis presented with severe pleuritic chest pain and hypoxemia three weeks after discharge following abdominal surgery. A pulmonary embolus was diagnosed by angiography and he was treated with heparin; the minimum arterial pO2 was 55 torr while O2 was being administered at a rate of 3 L/min. During this therapy, he developed abdominal pain. Computerized tomography suggested splenic infarction, which was documented by radionuclide liver-spleen scan and magnetic resonance imaging (MRI); the patient's spleen had been normal at exploratory laparotomy three weeks previously. No source for emboli was identified in the deep venous system by MRI. Although splenic infarction has been reported in patients with sickle cell trait at high altitude, this is the first reported case of splenic infarction secondary to the hypoxemia of pulmonary embolism in a patient with sickle cell trait. The spleen is subject to infarction in sickle cell trait because blood flow is slow through a hypoxemic and acidemic environment. The additional hypoxemia due to pulmonary embolism is presumed, in our patient, to have created a local splenic environment which permitted infarction to occur.

Blood pressure and other cardiovascular disease risk factors in black adults with sickle cell trait or glucose-6-phosphate dehydrogenase deficiency

In this study, we examined the relationship of two common genetic markers in black populations, sickle cell trait and glucose-6-phosphate dehydrogenase (G-6-PD) deficiency, to cardiovascular risk factors. The subjects were Nigerian civil servants in Benin City, Nigeria. We measured blood pressure, height, weight, sickle cell hemoglobin, G-6-PD, proteinuria, microalbuminuria and fasting serum cholesterol, high-density lipoprotein cholesterol (HDL), triglycerides, apoprotein (APO) AI, and APO B. Data were collected on age, alcohol consumption, cigarette smoking, job status, and years lived in an urban area. There were 257 males (3 SS hemoglobin, 73 AS, 181 AA) and 69 females (23 AS, 46 AA). In comparing cardiovascular risk factors, males differed only in percent of smokers (31.5 in AS vs. 17.8 in AA, P less than 0.01). Among females, only high-density lipoprotein (HDL) cholesterol differed (61.5 mg/dl in AS vs. 52.4 in AA, P less than 0.01). We hypothesize that females with sickle cell trait are more likely to use oral contraceptives than nontrait females. If so, the high-estrogen oral contraceptives available in Nigeria could elevate HDL. G-6-PD deficiency status among males (52 deficient, 207 nondeficient) and females (1 deficient, 5 carriers, 65 nondeficient) was not related to any of the cardiovascular risk factors. We conclude that sickle cell hemoglobin trait and G-6-PD deficiency are not useful genetic markers for risk factors for cardiovascular disease.

Effects of glucose-6-phosphate dehydrogenase deficiency upon sickle cell anaemia

The levels of glycated haemoglobin, fetal haemoglobin and methaemoglobin in 618 Saudi subjects were determined. A statistically significant decrease in the percentage of glycated haemoglobin was observed in all haemoglobinopathic groups studied in comparison to normal controls. However, there was no significant difference in the percentage of glycated haemoglobin in patients with sickle cell anaemia when compared with those sickle cell subjects who were also glucose-6-phosphate dehydrogenase deficient. This suggests that there is little survival advantage or disadvantage in the combination of glucose-6-phosphate dehydrogenase deficiency and sickle cell anaemia.

Sickle-cell trait as a risk factor for sudden death in physical training

Case reports of sudden death during exertion have not established an association between the sickle-cell trait (hemoglobin AS) and exercise-related death. To test this association, all deaths occurring among 2 million enlisted recruits during basic training in the U.S. Armed Forces in 1977 to 1981 were classified from autopsy and clinical records as non-sudden deaths or as sudden deaths explained or unexplained by preexisting disease. On the basis of known numbers of entering recruits (according to race, age, and sex) and published prevalence rates for hemoglobin AS (8 percent for black and 0.08 percent for nonblack recruits), death rates (per 100,000) were 32.2 for sudden unexplained deaths, 2.7 for sudden explained deaths, and 0 for non-sudden deaths among black recruits with hemoglobin AS, as compared with 1.2, 1.2, and 0.7 among black recruits without hemoglobin S and 0.7, 0.5, and 1.1 among nonblack recruits without hemoglobin S. Among black recruits the relative risk of sudden unexplained death (hemoglobin AS vs. non-hemoglobin S) was 27.6 (95 percent confidence interval, 9 to 100; P less than 0.001), whereas among all recruits this risk was 39.8 (95 percent confidence interval, 17 to 90; P less than 0.001). The relative risk of sudden unexplained death among all recruits increased with age (P less than 0.04), from 13 (ages 17 to 18) to 95 (ages 26 to 30). We conclude that recruits in basic training with the sickle-cell trait have a substantially increased, age-dependent risk of exercise-related sudden death unexplained by any known preexisting cause.

Screening for sickle cell trait: the Veterans Administration National Sickle Cell Program

Results of the Veterans Administration Sickle Cell Program for a period of 10 years are presented. We screened 370,250 patients; 404,341 attended educational sessions, and 38,347 had individual counseling sessions. Sickle cell trait was present in 6.4% of patients, and HbC trait was present in 1.8%. The clinically significant disorders HbSC disease, sickle cell anemia, and sickle beta thalassemia were present in 0.41% of individuals screened. A large number of uncommon variants were detected. The program enhanced the awareness of and the approach to evaluation of hemoglobinopathies.

Intraoperative death during caesarian section in a patient with sickle-cell trait. The Anaesthesia Advisory Committee to the Chief Coroner of Ontario

The case of a woman with sickle cell trait who sustained a cardiac arrest and died during a Caesarian section under general anaesthesia is reported. Because the common causes of intraoperative hypoxia and shock were ruled out in this case, we believe that death was due to severe concealed aorto-caval compression. After delivery, the release of a large volume of hypoxaemic, acidotic blood with sickled cells could cause cardiac depression and arrest. The fact that the patient's mucous membranes were pink and she was haemodynamically stable while her uterus was cyanotic prior to delivery provides some positive evidence for this hypothesis. We emphasize that while complications secondary to sickle cell trait during general anaesthesia are very rare, they can occur. We discuss methods of monitoring such patients.

Age and prevalence of sickle-cell trait in a large ambulatory population

We performed hemoglobin electrophoresis in 30,400 apparently healthy black individuals in the Washington D.C. Metropolitan area, who were participating in a community based sickle-cell screening program during the period 1978-1985. The overall prevalence of sickle-cell trait was 6.7%. The frequency of sickle-cell trait in various age groups, which included young children, adults, and individuals over 65 years of age, ranged from 6.4 to 7.4%. There were no statistically significant differences in the prevalence of sickle-cell trait among the various age groups, nor did we detect a significant trend for increasing or decreasing sickle cell frequency with advancing age (P = 0.418). Thus, in this population sickle-cell trait appears to have no effect on longevity. If the various complications of sickle-cell trait reported in the literature are not fortuitous, their frequency and/or severity must be too low to affect prevalence figures.

Sickle Cell Trait, Exercise, and Altitude

In brief: Sickle cell trait is generally benign and does not shorten life, but it may confer some risk with extremes of exercise or altitude. For example, the risk of splenic infarction at mountain altitudes is small but real, and exists for whites as well as for blacks. In contrast, the risk of exercise-related death may not be increased for persons with sickle cell trait; there is still no cogent evidence that the trait predisposes to exertional rhabdomyolysis or death. It is important to realize that sickle cell trait is no barrier to outstanding athletic performance, and that athletes with the trait should take the same precautions as any other athletes-no more, no less.

Influence of HbS levels upon the hematological and clinical characteristics of sickle cell trait

The variable concentration of HbS in individuals with sickle cell trait led us to study the relationship between HbS level and selected vascular events in 355 hospitalized black men with sickle cell trait. There were significant differences in hemoglobin concentration and mean corpuscular volume found in four groups divided by their HbS level, the lowest proportion of HbS (less than 30%) being associated with the lowest hemoglobin concentration (12.6 g/dl) and MCV (77 fl). The percent HbS did not influence the incidence of pulmonary embolism, thrombophlebitis, myocardial infarction, cerebrovascular accident, or idiopathic hematuria. Our results suggest that HbS level does not influence vascular disease, and while certain hematological alterations occur, they are very unlikely to have any clinical significance. Regardless of the proportion of HbS, sickle cell trait in black men is benign.

Glucose-6-phosphate dehydrogenase deficiency and incidence of cataract in Sicily

The incidence of G6PD deficiency in red blood cells of 241 Sicilian cataractous patients (138 males and 103 females) and in the lens of 32 subjects (15 males and 17 females) of the same group was evaluated. The incidence of G6PD deficiency was significantly higher than expected (p less than 0.001), both in RBCs and in lens. The results suggest that G6PD deficiency is a risk factor for cataract both in hemizygous males and heterozygous females.

Review: the sickle hemoglobinopathies--genetic analyses of common phenocopies and new molecular approaches to treatment

Within the very large group of sickle cell hemoglobinopathies several phenocopy clusters exist. These can be conveniently classified as: 1) conditions in which HbA and S are present, 2) disorders where HbS is the predominant hemoglobin, and 3) the HbSF phenotype. This review will focus on distinguishing the genotype of these common phenocopies as well as new potential approaches to therapy.

Hemoglobin S levels in sickle cell trait individuals

Changes in Department of Defense regulations now permit persons with sickle cell trait to serve in all service branches. However, for purposes of the regulation, sickle cell trait is defined as 41% or less S hemoglobin. Our screening experience, based on 397 individuals with sickle cell trait, with quantitative scan of cellulose acetate electrophoretic sheets, indicates that 20-40% (depending on definition of terms) of individuals with sickle cell trait would be excluded by this criterion.