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We have described a patient with sickle cell trait who, after severe exertion, had rhabdomyolysis, acute renal failure, and disseminated intravascular coagulation secondary to sickling. Autopsy showed the characteristic histopathology of sickle cell crisis and not terminal sicklemia.
We investigated the possibility that persons with sickle cell trait who reside chronically at moderately high altitude might develop impaired splenic reticuloendothelial function. Seventeen healthy young black men with sickle trait who had lived at greater than or equal to 1,609 m for greater than or equal to 10 years participated in the study along with 25 matched control subjects with normal hemoglobin. Splenic function was assessed by radionuclide liver-spleen scanning and by red cell pit counts. No evidence of impaired splenic function was found in the sickle trait group. The data suggest that long-term residence at moderately high altitude does not place persons with sickle cell trait at risk for splenic dysfunction.
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.
BACKGROUND: The health risks associated with sickle cell trait are minimal in this sizable sector of the world's population, and many of these patients have no information about their sickle cell status. Splenic syndrome at high altitude is well known to be associated with sickle cell trait, and unless this complication is kept in mind these patients may be subjected to unnecessary surgery when they present with altitude-induced acute abdomen. METHODS: Four patients were admitted to the surgical ward with a similar complaint of acute severe left upper abdominal pain after arrival to the mountainous resort city of Abha, Saudi Arabia. All were subjected to splenectomy because of lack of suspicion regarding sickle cell status. RESULTS: Histologic examination of the spleen showed all patients had sickle cells in the red pulp. On further assessment all were found to have sickle cell trait with splenic infarction. In a similar study of 6 patients with known sickle cell disease who had comparable problems when they travelled to the Colorado mountains, all made an uncomplicated recovery with conservative management. CONCLUSIONS: In ethnically vulnerable patients with splenic syndrome, sickle cell trait should be ruled out before considering splenectomy. These patients could respond well to supportive management, and splenectomy would be avoided.
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.
Cerebrovascular complications of sickle cell anemia are well known to be one of the more common causes of stroke in the pediatric age group. Although it is far less common, the association of stroke with sickle cell trait has been described in young adults and only twice in children in the English literature. In this report, we describe a case of a posterior circulation infarct occurring in a 12-year-old male who also had a normal variant vertebral artery, which may have been a contributing factor in his presentation. The literature is reviewed and other possible risk factors for stroke in sickle cell trait are discussed.
The physical and physiological behavior of sickle cell trait carriers (AS) is somewhat equivocal under strenuous conditions, although this genetic abnormality is generally considered to be a benign disorder. The occurrence of incidents and severe injuries in AS during exercise might be explained, in part, by the lactic acidosis due to a greater lactate influx into AS red blood cells (RBCs). In the present study, the RBC lactate transport activity via the different pathways was compared between AS and individuals with normal hemoglobin (AA). Sixteen Caribbean students, nine AS and seven AA, performed a progressive and maximal exercise test to determine maximal oxygen consumption. Blood samples were obtained at rest to assess haematological parameters and RBC lactate transport activity. Lactate influxes [total lactate influx and monocarboxylate transporter (MCT-1)-mediated lactate influx] into erythrocytes were measured at four external [14C]-labeled lactate concentrations (1.6, 8.1, 41, and 81.1 mM). The two groups had similar maximal oxygen consumption. Total lactate influx and lactate influx via the MCT-1 pathway were significantly higher in AS compared with AA at 1.6, 41, and 81.1 mM. The maximal lactate transport capacity for MCT-1 was higher in AS than in AA. Although AS and AA had the same maximal aerobic physical fitness, the RBCs from the sickle cell trait carriers took up more lactate at low and high concentrations than the RBCs from AA individuals. The higher MCT-1 maximal lactate transport capacity found in AS suggests greater content or greater activity of MCT-1 in AS RBC membranes.
To determine whether sickle-cell trait and glucose-6-phosphate dehydrogenase deficiency influence the course and fatality rates of certain diseases requiring hospitalization, especially those associated with thrombotic phenomena, we conducted a co-operative study of 65,154 consecutively admitted, black male patients in 13 Veterans Administration hospitals. The overall frequency of sickle-cell trait was 7.8 per cent and of glucose-6-phosphate dehydrogenase dificiency 11.2 per cent. Both conditions were present in 0.9 per cent of those examined. There were regional, but no age-dependent, differences in the frequency of sickle-cell trait. Sickle-cell trait had no effect on average age at hospitalization or death, overall mortality, length of hospitalization on medical and surgical wards and frequency of any diagnosis, except essential hematuria and pulmonary embolism. Although statistically significant (P less than 0.001), the differences for the latter were small (1.5 per cent of all patients with normal hemoglobin and 2.2 per cent of patients with sickle-cell trait). Glucose-6-phosphate dehydrogenase deficiency had no adverse effect.
Serum cortisol levels of 100 children 3-10 years old with various haemoglobinopathies were measured. The mean cortisol levels of sickle cell trait, sickle cell disease, beta-thalassemia minor and alpha 2-thalassemia were significantly (P < 0.05) lower than those of normal subjects. The decrease in cortisol levels varied from 25 (in the sickle cell trait group) to 57 per cent (in the alpha 2-thalassemia group) of the mean cortisol levels of the control group. These results suggest the presence of hypoadrenalism and its possible association with the indicated haemoglobinopathies.
Unilateral hematuria is a vaso-occlusive complication of the sickle syndromes, especially the sickle cell trait. Treatment is usually ineffective, and the duration is variable, often prolonged and subject to recurrences. In sickle cell trait hematuria is usually the only consequence of sickling, possibly because the unique renal countercurrent mechanism may result in a milieu more prone to sickling in the medullary circulation than in the vasculature of other organs. Urea in vitro inhibits gelation of deoxygenated sickle hemoglobin. In 2 previously reported cases of sickle cell trait hematuria ceased within 3 days with oral urea therapy. We describe another such patient in whom hematuria also ceased by day 3 with oral urea. Although clinical trails with intravenous urea were ineffective in shortening the course of sickle crisis, urea may have an enhanced effectiveness in the renal medulla where the propensity for sickling may be much greater than in other organs. If these observations are confirmed in a controlled study, oral urea therapy would emerge as an effective, relatively innocuous and inexpensive treatment for this frustrating condition.
Splenic infarction in patients with sickle cell trait is usually related to hypoxic conditions, while non-hypoxia-related infarcts are extremely rare. We report on a case of a 17-year-old male patient, living at sea level, who developed a severe left upper quadrant abdominal pain during the course of a febrile episode. On physical examination he had a mildly palpable but extremely painful spleen. A spleen scan revealed 2 areas of impaired radionucleide distribution. Hepatic enzymes were moderately increased and the IgM anti-EBV antibodies positive. Hemoglobin electrophoresis revealed the presence of 42% of hemoglobin S. A probable diagnosis of splenic infarction was established in a patient with sickle cell trait, during the course of infectious mononucleosis. The patient was treated symptomatically. The conditions of splenic congestion induced by the EBV infection and the high-grade fever may have contributed to splenic sequestration and subsequent infarcts.
Three West-Indian black siblings with the sickle cell trait developed retroperitoneal fibrosis, a previously unreported association. Other well known renal manifestations associated with the sickle cell trait were also present in some of these cases and included renal medullary necrosis and spontaneous hematuria. It is postulated that the sickling of the erythrocytes in the periureteral vessels resulted in thrombosis, ischemia, reactive scarring and progressive fibrosis indistinguishable from the known histological picture of retroperitoneal fibrosis. The finding of fibrin thrombi in the small veins of the fibrotic tissue of one of these patients would support this explanation.
A Caucasian with sickle cell trait (54% A, 43% S hemoglobin) had symptoms and signs of chronic hemolytic anemia as well as splenic infarction while living at very high altitude (in excess of 2,800 m). Trips from sea level back to high altitude repeatedly precipitated pulmonary infarctions. All symptoms and evidence of hemolysis resolved at low altitude.
The significantly higher incidence of both sickle cell trait (SCT) and sudden infant death syndrome (SIDS) in the black population suggests that SCT and SIDS may be epidemiologically related. To study this possibility, we identified, for the period of February 1990 to February 1992, all infants with SCT born in Los Angeles County whose disease was diagnosed through the California Newborn Screening Program. We matched these infants with all confirmed cases of SIDS in Los Angeles County from February 1990 to March 1993. Three cases of SCT among 589 infants confirmed to have had SIDS were identified. The incidence of SIDS was 1.25/1000 live births for the general population versus 0.58/1000 cases for the SCT group. This finding remained unchanged when rates were adjusted for ethnicity. We conclude that infants born with SCT are not at increased risk of dying of SIDS.
In order to determine if sickle-cell trait (SCT) represents an inherent adverse effect on response to training, we objectively evaluated exercise performance in 22 healthy, black men with SCT (hemoglobin AS) and 15 controls (hemoglobin AA) before and after seven weeks of army basic training at an altitude of 1270 m. An incremental exercise test to exhaustion on a cycle ergometer was used. Before basic training, peak exercise measurements did not reveal significant differences between groups other than a slightly lower, albeit significant, value for oxygen uptake (VO2) per kilogram (42 +/- 1 vs 45 +/- 1.4 mL/min per kilogram) for the SCT group. Both groups experienced modest overall cardiovascular improvement reflected in both peak and submaximal exercise responses. No statistically significant difference was observed between the SCT and the control groups at the end of basic training for any of the measured variables at peak exercise, including power (258 +/- 6 vs 266 +/- 9W), VO2 (3.24 +/- .06 vs 3.36 +/- .16 L/min), VO2 per kilogram (46 +/- 0.7 vs 46 +/- 1.2), minute ventilation (138 +/- 4 vs 147 +/- 8 L/min), heart rate (185 +/- 2 vs 184 +/- 3 beats per minute), oxygen pulse (17.6 +/- .3 vs 18.4 +/- 1 mL/min per beat), as well as anaerobic threshold (1.81 +/- .04 vs 1.80 +/- .06 L/min), respectively. No medical problems directly attributed to SCT were reported; it remains uncertain, however, whether a seizure experienced by one of the other SCT basic trainees after a two-mile run was SCT related. The results of this study would, therefore, suggest that for the majority of individuals who possess SCT, the response to the moderate training regimen provided by army basic training is not impaired.
Sickle cell trait (SCT) is a genetic disease affecting the synthesis of normal hemoglobin (Hb) marked by the heterozygous presence of HbA and HbS. It is thought that exercise tolerance and aerobic capacity could be limited in SCT carriers, but that the co-existence of alpha-thalassemia with SCT (SCTAT) could improve exercise response. To examine these issues, we compared the characteristics of VO2 kinetics during a constant heavy exercise among athletes carrying either the SCT (n = 6), the SCTAT (n = 9), or the normal Hb (control group; n = 10). After determination of maximal power output (Ppeak), all subjects underwent a constant heavy cycling exercise lasting 9 min at approximately 70 % Ppeak. Pulmonary VO2 and cardio-respiratory parameters were measured breath-by-breath and the VO2 response was modelled using non-linear regression techniques. The time constant of the VO2 primary component and oxygen deficit were not significantly different among the three groups. The VO2 slow component was 28 % and 33 % higher (p < 0.05) in SCT and SCTAT than in the control groups, respectively. Altogether, athletes with the SCT and the SCTAT had higher heart rate at the beginning (+ 5.2 %) and the end (+ 7.4 %) of the slow component compared to the control group (p < 0.05). These results suggest that SCT and SCTAT subjects are not limited during the first exercise minutes, but are prone to exercise intolerance and to lower aerobic capacity thereafter, due to a higher VO2 slow component, and that alpha-thalassemia does not improve exercise response. The finding of a higher slow component in SCT and SCTAT athletes was possibly due to the loss of O2 availability to muscles, additional fiber recruitment and/or higher cardiac load with time.
In the community great efforts have been made to educate those with sickle cell trait that their condition is not a handicap and that they are fit to lead a normal life. It would be seen as a retrograde step for the Armed Forces to imply that they are in some way unfit for normal duties. The evidence presented demonstrates that with the exception of a small excess risk of sudden unexplained death during training there is no objection to recruiting those with sickle cell trait into the Royal Navy. At present those with sickle cell disorders are barred from service in the Royal Marine Commandos and from diving, submarine and aircrew service. On the basis of the evidence presented in this review a case can be made for allowing those with sickle cell trait to enter as aircrew in helicopters but not as pilots. In view of the requirements for military divers to operate in cold water under stressful conditions the exclusion of those with sickle cell trait is entirely justified. The overriding requirement must be the safety of both the affected individual and of others and the current regulations reflect this. Screening of all recruits and officer entrants in appropriate racial groups is not performed at present but would allow counselling and advice to be given to those affected by sickle cell trait at an early stage of their careers and the reasons for their exclusion from certain branches fully explained either by establishment Medical Officers or by the haematologist.(ABSTRACT TRUNCATED AT 250 WORDS)