Sports haematology

While the crucial role of haemoglobin in aerobic exercise has been well accepted, there is still a great deal of controversy about the optimal haematological parameters in the athletic population. The initial part of this review will examine the question of anaemia in athletes. The most common finding in athletes is a dilutional pseudoanaemia that is caused by a plasma volume expansion, rather than an actual blood loss. It is not a pathological state and normalises with training cessation in 3 to 5 days. This entity should be distinguished from conditions associated with lowered blood counts, such as intravascular haemolysis or iron deficiency anaemia. The evaluation of true anaemia states in the athlete must take into account not only blood losses secondary to exercise, such as foot strike haemolysis or iron losses through sweat, but non-athletic causes as well. Depending on the age and sex of the athlete, consideration must be given to evaluation of the gastrointestinal or genitourinary systems for blood loss. Finally, a comprehensive nutritional history must be taken, as athletes, especially women, are frequently not consuming adequate dietary iron. The second section of the paper will deal with the very contentious issue of sickle cell trait. While there have been studies demonstrating an increased risk of sudden death in people with sickle cell trait, it is still quite rare and should not be used as a restriction to activity. Further, studies have demonstrated that patients with sickle cell trait have an exercise capacity that is probably normal or near normal. However, in the cases of sudden death, it has been secondary to rhabdomyolysis occurring among sickle cell trait athletes performing at intense exertion under hot conditions, soon after arriving at altitude. The recommendations are that athletes with sickle cell trait adhere to compliance with the general guidelines for fluid replacement and acclimatisation to hot conditions and altitude. The final section of the paper examines the issue of haematological manipulation for the purposes of ergogenic improvement. Although experiments with blood doping revealed improvements in running time to exhaustion and maximal oxygen uptake, the introduction of recombinant erythropoietin has rendered blood doping little more than a historical footnote. However, the improvements in performance are not without risk, and the use of exogenous erythropoietin has the potential for increased viscosity of the blood and thrombosis with potentially fatal results. Until a definitive test is developed for detection of exogenous erythropoietin, it will continue to be a part of elite athletics.

Unusually large von Willebrand factor multimers increase adhesion of sickle erythrocytes to human endothelial cells under controlled flow

The interactions of normal erythrocytes and erythrocytes from patients having hemoglobin S hemoglobinopathies with normal human endothelial cells (EC) were investigated under flow conditions. When EC supernatant, containing 2.8-11.0 U/dl of von Willebrand factor (vWF) antigen and vWF multimeric forms larger than those present in normal plasma, was the red blood cell (RBC)-suspending medium instead of serum-free medium (SFM), the adhesion of sickle RBC, but not normal RBC, to endothelial cells was greatly increased (range of enhancement of sickle RBC adhesion, 2- to 27-fold). Adhesion of sickle RBC to endothelial cells was reduced to near serum-free levels when EC supernatant was immunologically depleted of vWF forms. Sickle RBC suspended in SFM containing 200 U/dl of purified vWF multimers of the type found in normal human plasma or 300 micrograms/ml human fibronectin were only slightly more adhesive to endothelial cells than sickle RBC suspended in SFM alone. These data indicate that unusually large vWF multimers produced by endothelial cells are potent mediators of the adhesion of sickle erythrocytes to endothelial cells. Vaso-occlusive crises in sickle cell anemia may be caused, at least in part, by adhesive interactions between the abnormal surfaces of sickle RBC and the endothelium after the release of unusually large vWF multimeric forms from stimulated or damaged endothelial cells.

The role of cytokines in sickle cell disease

Sickle cell disease (SCD) is characterized by chronic hemolysis, frequent infections, and recurrent occlusions of microcirculation, which cause painful crises and result in chronic organ damage and failure. Occlusions of the microcirculation and infections are important factors that stimulate the production of cytokines and acute-phase proteins. Cytokines seem to be involved with several possible mechanisms in the pathogenesis of vasoocclusive phenomena in SCD: vascular endothelial activation, induction of red-cell adhesiveness to vascular endothelium, induction of neutrophil adhesiveness to endothelium, development of vascular intimal hyperplasia, platelet activation, endothelin-1 production, and dysregulation of endothelial apoptosis. Cytokines are also thought to be involved in the regulation of hemopoiesis, the inhibition of immune functions, and the development of growth deficits. Investigation of cytokines in SCD patients will elucidate the pathogenesis of the disease and its complications and may help in assessing disease severity and prognosis.

Framing the research agenda for sickle cell trait: building on the current understanding of clinical events and their potential implications

Sickle Cell Trait (HbAS), the heterozygous state for the sickle hemoglobin beta globin gene is carried by as many as 100 million individuals including up to 25% of the population in some regions of the world (World Health Organization, Provisional agenda item 4.8, EB117/34 (22 December 2005) or World Health Organization, Provisional agenda item 11.4 (24 April 2006)). Persons with HbAS have some resistance to falciparum malaria infection in early childhood (Piel FB, Patil AP, Howes RE, et al., Nat Commun 2010;1104:1-7 and Aidoo M, Terlouw DJ, Kolczak M, et al., Lancet 2002;359:1311-1312) and as a result individuals with HbAS living in malarial endemic regions of Africa have a survival advantage over individuals with HbAA. Reports from the US emphasize possible health risks for individuals with HbAS including increased incidence of renal failure and malignancy, thromboembolic disorders, splenic infarction as a high altitude complication, and exercise-related sudden death. The National Heart, Lung, and Blood Institute, National Institutes of Health convened a workshop in Bethesda, Maryland on June 3-4, 2010, Framing the Research Agenda for Sickle Cell Trait, to review the clinical manifestations of HbAS, discuss the exercise-related sudden death reports in HbAS, and examine the public health, societal, and ethical implications of policies regarding HbAS. The goal of the workshop was to identify potential research questions to address knowledge gaps.

Hyposplenism: comparison of different methods for determining splenic function

Asplenic patients are at risk for pneumococcal sepsis. Patients with hyposplenic function, such as associated with sickle cell disease (SCD), are also at risk. However, tests to assess splenic function are either unavailable or lacking standardization. The aim of this study was to compare different methods for determining splenic function. Eighteen patients with SCD (i.e., 10 heterozygous (SC) and 8 homozygous (SS) SCD patients), and eight splenectomized patients were compared to 10 controls. All subjects underwent spleen scintigraphy, after which functional splenic volumes (FSV) were calculated. FSV was compared to immunological function and B cell-subsets, as well as phagocytic function represented by the presence of Howell Jolly bodies (HJB) and percentages of pitted red cells (PIT). Heterozygous SCD (SC) patients had increased splenic volumes, but diminished FSV, homozygous SCD (SS) patients were asplenic. Splenectomized and SS patients had a strongly reduced phagocytic and immunological function. SC patients had reduced anti-polysaccharide responses without an increase in PIT. FSV correlated significantly with phagocytic and immunological function. HJB were indicative of splenic dysfunction, HJB absence was not indicative of normal functioning splenic tissue. Although visualizing HJB is methodologically advantageous to PIT, both are valid biomarkers of splenic dysfunction. The amount of non-switched memory B cells is strongly correlated to FSV.

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.

Endothelial cell P-selectin mediates a proinflammatory and prothrombogenic phenotype in cerebral venules of sickle cell transgenic mice

Whereas the adhesion of leukocytes and erythrocytes to vascular endothelium has been implicated in the vasooclusive events associated with sickle cell disease, the role of platelet-vessel wall interactions in this process remains undefined. The objectives of this study were to: 1) determine whether the adhesion of platelets and leukocytes in cerebral venules differs between sickle cell transgenic (betaS) mice and their wild-type (WT) counterparts (C57Bl/6) under both resting and posthypoxic conditions, and 2) define the contributions of P-selectin to these adhesion processes. Animals were anesthetized, and platelet and leukocyte interactions with endothelial cells of cerebral postcapillary venules were monitored and quantified using intravital fluorescence microscopy in WT, betaS, and chimeric mice produced by transplanting bone marrow from WT or betaS mice into WT or P-selectin-deficient (P-sel(-/-)) mice. Platelet and leukocyte adhesion to endothelial cells in both unstimulated and posthypoxic betaS mice were significantly elevated over WT levels. Chimeric mice involving bone marrow transfer from betaS mice to P-sel(-/-) mice exhibited a profound attenuation of both platelet and leukocyte adhesion compared with betaS bone marrow transfer to WT mice. These findings indicate that betaS mice assume both an inflammatory and prothrombogenic phenotype, with endothelial cell P-selectin playing a major role in mediating these microvascular responses.

Sickle cell considerations in athletes

This article highlights the exertional-sickling collapse syndrome in athletes with sickle cell trait (SCT). It covers all aspects of this syndrome, including pathophysiology, new research on microcirculatory changes, clinical features, differential diagnosis, prevention, and treatment. Also covered in this article are other clinical concerns for athletes with SCT, including lumbar myonecrosis, splenic infarction, hematuria, hyposthenuria, and venous thromboembolism. The final section offers practical points on athletes with sickling hemoglobinopathies more serious than SCT.

Exercise and hypoxia increase sickling in venous blood from an exercising limb in individuals with sickle cell trait

PURPOSE

The association between sickle cell trait (SCT) and complications related to exercise may be explained if exercise-induced sickling interferes with capillary blood flow and causes tissue ischemia and functional abnormalities. To test this hypothesis, we measured sickling and blood gas values in venous and arterial blood of an exercising limb in subjects with SCT and in controls.

SUBJECTS AND METHODS

The study consisted of 15 subjects with hemoglobin AS (SCT group) and 15 subjects with hemoglobin AA (control group). Each performed two maximal arm crank exercise tests, one at 1,270 meters and one at simulated 4,000 meters.

RESULTS

At 1,270 meters, axillary venous sickling increased significantly (p less than 0.05) from (mean +/- SD) 1.0 +/- 1.0% at rest to 2.3 +/- 2.6% during peak exercise. At simulated 4,000 meters, sickling increased significantly (p less than 0.001) from 1.5 +/- 1.2% to 8.5 +/- 7.1%. A wide range of sickling during peak exercise was observed (1% to 25%). One minute after exercise at simulated 4,000 meters, venous sickling remained elevated (7.2 +/- 7.8%) despite high levels of oxygen saturation. Arterial sickling (less than 1%) was present in only two subjects. There was no significant difference in oxygen consumption (29.4 +/- 3 versus 30.7 +/- 4 mL/kg/minute) between the subjects with SCT and the controls, nor was there a correlation between exercise performance and sickling (r less than 0.2).

CONCLUSION

We conclude that exercise at 1,270 meters slightly, albeit significantly, increased sickling in blood from an exercising limb and that simulated 4,000 meters dramatically potentiated this effect. Sickling in the effluent blood of an exercising limb does not appear to measurably affect overall maximal arm crank exercise performance.

Physical fitness indices and anthropometrics profiles in schoolchildren with sickle cell trait/disease

The current studies aimed at determining physical fitness indices and anthropometrics profiles of school children with sickle cell trait (SCT) and sickle cell disease (SCD). Male school children (150) comprising 3 Groups participated in the studies. Group 1 has 50 normal healthy controls, while Groups 2 and 3 each has 50 children who were suffering from SCT and SCD, respectively. Anthropometrics measurement and parameters of physical fitness were assessed in all subjects. All children were also subjected to a 5-min running exercise test on a flat motorized treadmill at speed corresponding to 5 km/hr. Throughout the test, heart rate was monitored and recorded during exercise and for 10-min during recovery. Blood lactate was measured before and 5 min following the completion of test. The mean values of lean body mass and height were lower in the SCD children (P < 0.05) compared with the healthy subjects and SCT individuals. Children with SCD exhibited a higher mean value (P < 0.05) for percent body fat and fat mass than the normal healthy subjects and SCT individuals. Although all groups tolerated well the treadmill exercise protocol, the SCD group exhibited higher (P < 0.05) mean values of heart rate during exercise than those observed in the SCT and normal control children. In addition, SCD children showed higher serum lactate values before and after treadmill exercise compared to the other groups. Children with SCD exhibit high level of adiposity; low level of fitness and their exercise performance appears to be physiologically more stressful as indicated by heart rate and blood lactate concentration responses.

Effects of progressive and maximal exercise on plasma levels of adhesion molecules in athletes with sickle cell trait with or without α-thalassemia

The aim of the study was to examine the effects of exercise on soluble vascular cell adhesion molecule-1 (sVCAM-1) and intercellular adhesion molecule-1 (sICAM-1) in sickle cell trait (SCT) athletes with or without α-thalassemia. Six athletes with SCT, seven athletes with both SCT and α-thalassemia (SCTAT), and seven control athletes (Cont) performed an incremental and maximal test on cycloergometer. Levels of sICAM-1 and sVCAM-1 were assessed at rest, immediately after the end of exercise, and 1, 2, and 24 h after exercise. Although Cont and SCTAT groups exhibited similar basal plasma levels of inflammatory and adhesion molecules, the SCT group had higher sVCAM-1 basal concentrations. Incremental exercise resulted in a significant increase of sVCAM-1 in all subjects, which remained elevated only in the SCT group during the recovery period. In conclusion, as sVCAM-1 increased with exercise and during the recovery period, our findings support the concept that SCT athletes might be at risk for microcirculatory disturbances and adhesive phenomena developing at rest and several hours after exercise. α-Thalassemia might be considered protective among exercising SCT subjects.

Nutrition and sickle cell disease

The role of protein and calorie deficiency in sickle cell disease remains poorly defined. While such features as growth retardation, impaired immune function, and delayed menarche do suggest a relationship between sickle cell disease and undernutrition, measurement of more direct nutritional parameters in these patients have yielded mixed results. Anthropometric measurements such as skinfold thickness are subnormal in many but not all reports. Serum protein levels are normal, but low values for serum lipids have been reported. Finally, one small study shows an improvement in both growth parameters and clinical course following caloric supplementation. A variety of micronutrient deficiencies have been suggested in sickle cell disease. Numerous case reports describing an exacerbation of the chronic anemia that was reversed by folic acid therapy led to routine folate supplementation. More recent studies have shown, however, that clinically significant folic acid deficiency occurs only in a small minority of sickle cell patients. Clearly, more work is necessary to define the cost/benefit ratio of routine folic acid supplementation. Pharmacological amounts of vitamin B6 and certain of its derivatives possess in vitro antisickling activities. Nevertheless, a small clinical trial failed to demonstrate any consistent hematologic effects of B6 supplementation. Several reports indicate that vitamin E levels are low in sickle erythrocytes. Since these abnormal red cells both generate excessive oxidation products and are more sensitive to oxidant stress, and because oxidants appear to play a role in ISC formation, vitamin E deficiency could well be linked to ISC formation and hemolysis. Small clinical trials, however, have again failed to produce a clear hematological response in sickle cell anemia. The role of zinc in sickle cell disease has received considerable attention. Though studies are generally small, most do support a relationship between sickle cell disease and zinc deficiency. Etiologic associations between zinc deficiency and such complications of sickle cell disease as poor ulcer healing, growth retardation, delays in sexual development, immune deficiencies, and high ISC counts have all been suggested. Most of these studies need further corroboration. Iron deficiency is now known to be a relatively common occurrence in sickle cell anemia, especially in children and pregnant women. The theoretical benefits of concomitant iron deficiency and sickle cell anemia remain to be proven in a controlled clinical trial.(ABSTRACT TRUNCATED AT 400 WORDS)

Transfusion and exchange transfusion in sickle cell anaemias, with particular reference to iron metabolism

The relationship between the number of units of blood transfused and indicators of iron status in 37 patients with sickle cell anaemia (Hb SS), SC disease (Hb SC) or S beta-thalassaemia has been studied. The correlation coefficient between serum ferritin and the number of units transfused was good (r = 0.86), provided that ferritin samples taken within one week following a crisis were excluded. The relationship of transfusion history to serum ferritin in the steady state showed a similar relationship to that previously observed for other multiply transfused patients. The serum ferritin taken within 7 days of a painful crisis was significantly greater than the serum ferritin from the same patients in the steady state (p less than 0.025). The serum alanine transaminase did not rise as consistently as the serum ferritin during crises; it correlated with the serum ferritin but not the transfusion burden in the steady state. Transferrin iron saturation correlated less clearly with transfusion history than serum ferritin (r = 0.62). Patients who had received exchange transfusions were less likely to be iron-overloaded (ferritin increment per unit of blood = 9.9 +/- 3.8 micrograms/l) than patients who had received an equivalent number of units by conventional transfusion (ferritin increment per unit of blood transfused = 25.1 +/- 2.42 micrograms/l).

Priapism in sickle cell disease: the case for early implantation of the penile prosthesis

OBJECTIVES

Recurrent ischemic priapism in sickle cell (SS) patients often leads to impotence. Blockage of venous outflow by sickle cells leads to anoxia of the cavernosal smooth muscle with subsequent replacement of the erectile tissue with dense fibrosis. This study evaluates the efficacy of early penile prosthesis implantation in patients with priapism associated with sickle cells disease.

METHODS

Our recent experience includes 6 SS patients with impotence resulting from repeated episodes of priapism and 1 SS patient who suffered penile autoamputation from prolonged tricorporeal low flow priapism. The average age was 26 years. Six patients underwent excision of fibrotic cavernosal sinusoidal tissue and placement of a malleable prosthesis. The autoamputation case was managed with a one-stage penile reconstruction using a forearm free-flap and a two-piece inflatable penile prosthesis.

RESULTS

All patients in our series are currently potent. Because of infection, 1 patient required removal and subsequent reinsertion of his prosthesis, and another has required revision.

CONCLUSION

Potency in the young SS patient with recurrent episodes of ischemic priapism may best be managed by a penile prosthesis. Early implantation may lessen the psychological trauma of repeated priapisms, and reduce the technical difficulties and complications associated with penile prosthetic insertion in the presence of dense fibrosis.

Effect of age on testicular function in adult males with sickle cell anemia

OBJECTIVES

To determine the effect of age on testicular function and fertility profile of adult males with homozygous sickle cell disease.

DESIGN

A comparative cross-sectional study.

SETTING

A university teaching hospital in Nigeria.

PARTICIPANTS

Twenty-two adult males with homozygous sickle cell disease and 20 healthy adult males with normal hemoglobin genotype.

MAIN OUTCOME MEASURES

Seminal indexes, serum concentration of reproductive hormones, body mass index (BMI), testicular volume index, and span-height difference of patients with homozygous sickle cell disease and normal subjects were compared. Also significant differences were sought between two age groups among patients and control subjects: those < or = 25 years old and those > 25 years of age.

RESULTS

The mean BMI, testicular volume index, serum T concentration, and indexes of semen quality of the patients with homozygous sickle cell disease were significantly lower than the values for the control subjects. In contrast, there was no significant difference in the mean concentration of FSH, LH, PRL, and mean span-height difference between both groups. Also, although no significant age-related effect on serum T concentration, testicular volume index, and sperm density was found in the subjects 18 to 40 years of age with normal hemoglobin genotype, patients > 25 years old with homozygous sickle cell disease had significantly higher mean serum T concentration and mean testicular volume index than those < or = 25 years old; their sperm density was also substantially higher.

CONCLUSION

Fertility is impaired in adult males with homozygous sickle cell disease probably as a result of abnormal hypothalamic or pituitary function. There is a significant amelioration of the hypogonadism, abnormal sexual function, and poor semen profile with increasing age.

Zinc status of children with sickle cell disease: relationship to poor growth

We examined the zinc status of 80 children with sickle cell disease (SCD) and 44 disease-free sibling controls aged 3 to 18 years. For both patients and controls, variations in serum zinc by age, type of hemoglobinopathy, and growth status were measured. The mean serum zinc concentration of patients was significantly lower than for controls (77.8 +/- 9.9 vs. 82.2 +/- 9.8 micrograms/dl, mean +/- 1SD, P less than .05). Serum levels of alkaline phosphatase (AP) and retinol-binding protein (RBP), two zinc-dependent proteins, were also lower among patients (AP: 171 +/- 66 vs. 243 +/- 97 IU/L, P less than .001; RBP: 1.92 +/- .9 vs. 2.77 +/- .9 mg/dl, P less than .001). Patients greater than or equal to 12 years of age (n = 34) had significantly lower zinc levels than those less than 12 years (74.5 +/- 8.4 vs. 80.3 +/- 10.3 micrograms/dl, P less than .01), and children with homozygous SCD (Hb SS, n = 55) had a more pronounced deficiency than those with a variant hemoglobinopathy (76.3 +/- 8.9 vs. 81.5 +/- 11.5, micrograms/dl, P less than .05). Patients classified as having "poor" growth (height-for-age less than 5th percentile, n = 24) had a lower serum zinc level than those with "normal" growth (72.8 +/- 8.0 vs. 79.8 +/- 10.0 micrograms/dl, P less than .01). Dietary intake data, body mass index, and serum total protein and albumin levels were similar for patients and controls, suggesting that zinc deficiency in SCD does not relate to inadequate dietary intake. The origin of low serum zinc levels in children with SCD is more likely to relate to factors such as increased urinary zinc excretion, chronic intravascular hemolysis, and/or zinc malabsorption.

Renal dysfunction in patients with sickle cell anemia or sickle cell trait

Patients with sickle cell anemia (Hb SS) or sickle cell trait (Hb AS) may present several types of renal dysfunction; however, comparison of the prevalence of these abnormalities between these two groups and correlation with the duration of disease in a large number of patients have not been thoroughly investigated. In a cross-sectional study using immunoenzymometric assays to measure tubular proteinuria, microalbuminuria, measurement of creatinine clearance, urinary osmolality and analysis of urine sediment, we evaluated glomerular and tubular renal function in 106 adults and children with Hb SS (N = 66) or Hb AS (N = 40) with no renal failure (glomerular filtration rate (GFR) > 85 ml/min). The percentage of individuals with microalbuminuria was higher among Hb SS than among Hb AS patients (30 vs 8%, P < 0.0001). The prevalence of microhematuria was similar in both groups (26 vs 30%, respectively). Increased urinary levels of retinol-binding protein or beta 2-microglobulin were detected in only 3 Hb SS and 2 Hb AS patients. Urinary osmolality was reduced in patients with Hb SS or with Hb AS; however, it was particularly evident in Hb SS patients older than 15 years (median = 393 mOsm/kg, range = 366-469) compared with Hb AS patients (median = 541 mOsm/kg, range = 406-722). Thus, in addition to the frequently reported early reduction of urinary osmolality and increased GFR, nondysmorphic hematuria was found in 26 and 30% of patients with Hb SS or Hb AS, respectively. Microalbuminuria is an important marker of glomerular injury in patients with Hb SS and may also be demonstrated in some Hb AS individuals. Significant proximal tubular dysfunction is not a common feature in Hb SS and Hb AS population at this stage of the disease (i.e., GFR > 85 ml/min).

Pain management in children with sickle cell disease

Sickle cell disease (SCD) is one of the most common inherited diseases worldwide. The disease is characterized by chronic hemolytic anemia, as well as acute and chronic complications. One of the most intractable problems encountered by children with SCD is the painful episode that results from tissue ischemia due to vaso-occlusion. Pain related to SCD is unique among pain syndromes due to the unpredictable, recurrent, and often persistent nature of the disease, as well as the recurring and essential need for the use of opioids. Painful vaso-occlusive episodes (VOE) are a principal cause of morbidity and account for a significant number of emergency department and hospital admissions. When untreated or inadequately managed, the pain of VOE may cause both short- and long-term consequences. Despite the fact that pain is an almost universal feature of the disease, children with SCD may form one of the most undertreated and understudied populations. One of the factors contributing to poor pain management is conflicting perceptions between patients, their families, and healthcare professionals about pain that is reported and analgesia that is required. Pain management guidelines have recently been published in an effort to overcome barriers in the assessment and management of pain related to SCD. Although there is considerable variability in the way SCD pain is managed, the standard treatment protocol for painful episodes has been rest, rehydration, and analgesia. However, pain control for children with SCD is often a difficult and complex process, and one that requires frequent systematic pain assessments and continuous adjustment of comfort measures, especially analgesics. There are a variety of analgesic agents to choose from, such as acetaminophen (paracetamol), oral or parenteral nonsteroidal anti-inflammatory drugs, and oral or parenteral opioids. Each of these options has advantages and disadvantages to their use. Continuous infusions of analgesics and patient controlled analgesia have been shown to be effective and widely used in hospital settings to manage severe pain. However, the opioid dose required to achieve pain relief varies considerably within each painful episode, from one episode to another, and between individual patients. Although not yet curable in humans, pain related to SCD can be effectively managed in most patients by using a comprehensive approach that incorporates pharmacologic, psychologic, behavioral, and physical pain management strategies.

Growth and development in children with sickle-cell trait. A prospective study of matched pairs

To ascertain if sickle-cell trait (Hb AS) impairs physical growth and cognitive development, we prospectively investigated 50 matched pairs of black children. For each child with Hb AS, an Hb AA child was matched at birth for sex, birth date, birth weight, gestational age, five-minute Apgar score and socioeconomic status. Between the ages of three and five years, the members of each matched pair were evaluated, with one month of one another, by persons "blind" to the hemoglobin genotype. Twelve outcome measurements were obtained at evaluation: height, weight, head circumference, skin-fold thickness, cross-sectional area of arm muscle, bone age, five scores of the McCarthy Scales of Children's Abilities, and the Peabody Picture Vocabulary Test. There were no statistically significant differences in these measurements favoring the AA group. The results show that children with sickle-cell trait in this age group have no deficits in standard measurements of growth and development and emphasize the importance of rigorous methods when clinical groups are assembled and compared.

Exertional rhabdomyolysis and renal failure in patients with sickle cell trait: is it time to change our approach?

Based upon numerous reported cases and despite widespread beliefs to the contrary, sickle cell trait (SCT) may be deemed a quantifiable risk factor in certain subsets of patients. As a result of common misconceptions regarding SCT, most individuals with the condition are generally not informed regarding the possible consequences of certain activities such as venturing to high altitudes or participating in overly exertional physical activities. Acute exertional rhabdomyolysis is a potentially serious clinical illness and is caused by skeletal muscle injury resulting in the release of myoglobin and other cellular contents, including creatine kinase, into the circulatory system. Mild to moderate cases of acute exertional rhabdomyolysis can cause metabolic disorders including hypernatremia, hyperkalemia, hyperphosphatemia, hypocalcemia, lactic acidosis and hyperuricemia. Severe cases may result in renal failure and even death. Several case reports have been published since the early 1970s describing significant morbidity and mortality of acute exertional rhabdomyolysis in patients with SCT. We present the case of a 27-year-old male with a past medical history significant only for SCT who presented after a 1.5 mile run with severe exertional rhabdomyolysis and subsequent acute renal failure requiring hemodialysis (HD). In presenting this case, we hope to raise awareness of a possible underlying cause to many cases of exertional rhabdomyolysis and encourage physicians to counsel their patients with SCT in order to avoid the significant morbidity and mortality that may be associated with the condition.

Prevalence of transcranial Doppler abnormalities in Nigerian children with sickle cell disease

Transcranial Doppler (TCD) ultrasonography helps to identify children with sickle cell disease (SCD) who are at an increased risk of stroke,making primary stroke prevention a reality. A cross-sectional study of145 Nigerian children aged ≥3 years with SCD was carried out to describe the pattern of cerebral blood flow (CBF) abnormalities. The mean time-averaged mean velocity (TAMV) was 152 ±27.0 cm/sec and122 ±22.0 cm/sec in Hb SS and Hb S1C group, respectively. Abnormal velocities were recorded in six (4.7%) of the Hb SS patients and none of the Hb S1C while conditional risk (CR) velocities were recorded in 19.7% of Hb SS (low conditional 11.0%, high conditional 8.7%) and low conditional in 5.6% of Hb S1C cases. Cerebral flow velocities showed a negative correlation with age and hematocrit. Compared with African-American children, Nigerian children with Hb SS disease have a considerably higher prevalence of CR velocities.

The significance of biliary sludge in children with sickle cell disease

The prevalence of cholelithiasis was studied prospectively by abdominal ultrasound (US) examination in 305 children with sickle cell disease aged 1-18 years (mean 10.45). Gallstones were present in 60 children (19.7%); an additional 50 had biliary sludge only (16.4%). On follow-up of 35 of the 50 children with sludge, 23 (65.7%) had developed gallstones and 5 had already had a cholecystectomy. Five continued to have sludge on follow-up while 7 were reported to have no sludge. Children with US evidence of sludge should be followed up regularly by US, and those who develop gallstones should undergo elective cholecystectomy. For those with biliary sludge only, we recommend elective cholecystectomy if there are hepatobiliary symptoms.

Peripheral vascular response to mild indirect cooling in patients with homozygous sickle cell (SS) disease and the frequency of painful crisis

1. In homozygous sickle cell (SS) disease, skin cooling is a common precipitating factor of the painful crisis which is associated with avascular necrosis of active bone marrow. Since skin cooling does not directly induce sickling, we have investigated the nature of the reflex vascular responses to mild cooling in SS patients in a steady state of the disease and compared them with their history of painful crises. 2. Experiments were performed in Jamaica on 60 male SS patients and 30 matched control subjects with normal haemoglobin (AA) genotype. Forearm blood flow (FBF) was measured by venous occlusion plethysmography and mean arterial pressure (MAP) by a Finapres device: forearm vascular resistance (FVR) was calculated as MAP/FBF. Cutaneous erythrocyte flux in forearm and hand was monitored by a laser Doppler meter. The contralateral hand was immersed in cool water at 16 degrees C for 2 min, 6 times, at random intervals of 0.5-3 min. 3. The first cool immersion evoked an increase in MAP, cutaneous vasoconstriction and a net increase in FVR in both AA and SS subjects. However, the direction of change in FVR varied between individuals such that 18 AA subjects showed an increase in FVR (constrictor group) while 12 showed a decrease in FVR, indicating vasodilatation in forearm muscle (dilator group). In contrast, 50 SS subjects showed an increase in FVR and only 10 showed a decrease in FVR. The proportion of subjects who showed net vasoconstriction was significantly greater in the SS than in the AA group (83% versus 60%, P = 0.03, chi 2 test). 4. By the sixth cool stimulus, the 'dilator' group of AA subjects showed no change in FVR while the 'dilator' group of SS patients showed an increase in FVR. We suggest that forearm muscle vasodilatation was the characteristic component of the alerting/defence response to novel or noxious stimuli which habituates on repetition. 5. In the whole group of SS patients, baseline values of cutaneous vascular resistance and FVR increased between stimuli, indicating persistent vasoconstriction, and the sixth cool stimulus still evoked cutaneous vasoconstriction and a net increase in FVR. In contrast, AA subjects showed an increase in baseline FVR between stimuli, but the sixth cool stimulus had no significant effect on cutaneous vascular resistances, or FVR. 6. In SS patients there were no associations between the direction of change in FVR evoked by the first cool stimulus and forearm circumference or skinfold thickness, concentrations of haemoglobin or fetal haemoglobin. However, the frequency of painful crises was significantly greater in the 'constrictor' group than in the 'dilator' group (0.36 versus 0.12/year, P = 0.04, Mann-Whitney test). 7. These results indicate that the primary reflex vasoconstrictor response evoked by mild cooling is stronger and more persistent in SS patients than in AA subjects and is particularly strong in SS patients who are most prone to painful crises. The results are consistent with the hypothesis that skin cooling may precipitate the painful crisis by causing reflex vasoconstriction in muscle, and possibly in bone marrow, so diverting blood flow away from the active marrow.

Kidney Function Decline among Black Patients with Sickle Cell Trait and Sickle Cell Disease: An Observational Cohort Study

BACKGROUND

Sickle cell trait and sickle cell disease are thought to be independent risk factors for CKD, but the trajectory and predictors of kidney function decline in patients with these phenotypes are not well understood.

METHODS

Our multicenter, observational study used registry data (collected January 2005 through June 2018) and included adult black patients with sickle cell trait or disease (exposures) or normal hemoglobin phenotype (reference) status (ascertained by electrophoresis) and at least 1 year of follow-up and three eGFR values. We used linear mixed models to evaluate the difference in the mean change in eGFR per year.

RESULTS

We identified 1251 patients with sickle cell trait, 230 with sickle cell disease, and 8729 reference patients, with a median follow-up of 8 years. After adjustment, eGFR declined significantly faster in patients with sickle cell trait or sickle cell disease compared with reference patients; it also declined significantly faster in patients with sickle cell disease than in patients with sickle cell trait. Male sex, diabetes mellitus, and baseline eGFR ≥90 ml/min per 1.73 m2 were associated with faster eGFR decline for both phenotypes. In sickle cell trait, low hemoglobin S and elevated hemoglobin A were associated with faster eGFR decline, but elevated hemoglobins F and A2 were renoprotective.

CONCLUSIONS

Sickle cell trait and disease are associated with faster eGFR decline in black patients, with faster decline in sickle cell disease. Low hemoglobin S was associated with faster eGFR decline in sickle cell trait but may be confounded by concurrent hemoglobinopathies. Prospective and mechanistic studies are needed to develop best practices to attenuate eGFR decline in such patients.