Red blood cell folate and serum vitamin B12 status in children with sickle cell disease

Folic acid supplementation in children with sickle cell disease: a randomized double-blind noninferiority cross-over trial

BACKGROUND

Children with sickle cell disease (SCD) in Canada are routinely supplemented with folic acid to provide sufficient folate for the increased demands of erythropoiesis. However, with the mandatory folic acid fortification of refined grains and pharmacotherapies that extend the lifespan of sickled red blood cells (RBC), this clinical practice is in question.

OBJECTIVES

This study aims to determine the efficacy of folic acid supplementation by measuring the effect of 12 ± 1 wk of 1 mg/d folic acid, compared with placebo, on concentrations of RBC folate (primary outcome), serum folate, and 1-carbon-related metabolites, and clinical outcomes in children with SCD.

METHODS

In this double-blind randomized controlled noninferiority cross-over trial, 31 children with SCD, aged 2-19 y, were enrolled and randomly assigned (1:1 with blocks of 4) to 1 mg/d folic acid, the current standard of care, or a placebo for 12 ± 1 wk. After a 12 ± 1 wk washout period, treatments were reversed.

RESULTS

The mean [95% confidence interval (CI)] difference in endline RBC folate concentrations across treatments was -179 (-260, -99) nmol/L, with the lower boundary of the CI exceeding noninferiority but the upper boundary not (P = 0.0001; modified intention-to-treat). There was no significant difference in the number of participants who had RBC folate deficiency after each treatment (P = 0.059). No participants presented with serum folate deficiency (<7 nmol/L). There were no significant differences observed in 1-carbon metabolite concentrations (total homocysteine, S-adenosylhomocysteine, S-adenosylmethionine, vitamin B12, or methylmalonic acid), hematological measures, nor clinical outcomes (specifically acute pain episodes or megaloblastic changes) when individuals were supplemented with folic acid in comparison with placebo.

CONCLUSIONS

Despite mandatory food fortification and advances in the medical treatment of SCD, it appears that some children with this condition may still benefit from daily folic acid supplementation. Whether this translates to improved clinical outcomes remains uncertain. This trial was registered at clinicaltrials.gov as NCT04011345 (https://clinicaltrials.gov/study/NCT04011345).

Cobalamin Deficiency in Children and Adolescents with Sickle Cell Disease

Background/Objective: Cobalamin (B12) deficiency is reported in 18% of adults with sickle cell disease (SCD) and only 10% without SCD; limited data are available on children. Diagnosing B12 deficiency is challenging given the lack of an established gold standard method of assessment and the unique renal features of SCD. B12 metabolism can be impacted by the clinical use of nitrous oxide gas (N2O), which is a standard therapy for SCD pain in some European countries. In response to emerging reports of neurologic sequalae in patients with SCD receiving N2O, we evaluated the prevalence of B12 deficiency in children with SCD pain. Methods: Secondary analysis of prospective blood and urine samples in children aged 3-21 hospitalized with SCD pain. B12 deficiency was defined as plasma methylmalonic acid (MMA) > 592 nmol/L or urine MMA/creatinine ≥ 2.2 mmol/mol. Results: Ninety-four children (13 ± 4 years, 54% female, 68% hemoglobin-SS, and 72% on hydroxyurea) were assessed. Further, 53% (50/94) had B12 deficiency diagnosed by either urine, plasma, or both; 27% (25/94) were deficient based on urine; 39% (37/94) were deficient by plasma; and 13% (12/94) were deficient by both plasma and urine. Plasma MMA and urine MMA/creatinine did not correlate with hemoglobin or mean corpuscular volume. Conclusions: B12 deficiency was common in children with SCD. The absence of a gold standard for diagnosing B12 deficiency compounded with the reliability issues of testing modalities make it impractical to determine whether this is an over- or under-estimation of the true prevalence. Future studies to better understand the dynamics of B12 metabolism during acute and steady states in SCD are warranted and could elucidate the influence of acute SCD pain on these biomarkers.

Low vitamin B12 blood levels in sickle cell disease: Data from a large cohort study in Tanzania

Sickle cell disease (SCD) is associated with high rates of undernutrition and stunting. Undernutrition in combination with chronic haemolysis may lead to deficiencies in micronutrients necessary for erythropoiesis. Here we examined selected levels of ferritin, vitamins B2 , B6 , B9 and B12 , and vitamin C that were measured in blood samples from 820 SCD patients from Tanzania with no history of hospital admission, infections or painful episodes in the previous 30 days. We studied children (0-8 years), early adolescents (9-14 years), late adolescents (15-17 years) and adults (≥18 years). Severely low levels of vitamin B12 were observed across the four age groups. Despite the lowered vitamin B12 concentrations, total homocysteine concentrations were normal across both genders in all age groups. We found no significant gender-related differences between the other measured micronutrients. In this large SCD population, spanning the whole life cycle, a low level of vitamin B12 was consistently found across both genders and all age groups. Given the pivotal role of vitamin B12 in cellular metabolism, particularly in erythropoiesis, more studies are required to unravel how to better detect clinically relevant vitamin B12 deficiency among SCD patients, and thus to identify more precisely those who need supplementation of vitamin B12 .

Management of Salter-Harris Type 1 Fracture Complicated with Osteomyelitis in a Sickle Cell Disease Patient: A Case Report and Review of Literature

Salter-Harris fractures may occur due to a single injury or repetitive stress fractures on the extremities. Type I to III fractures are managed medically, while types IV and V, which are rare, are treated surgically. In the pediatric population, Salter-Harris I fractures of the distal tibia are commonly seen, and management of such fractures are well established in the literature. Despite the availability of a wide range of treatment for such fractures, osteonecrosis or avascular necrosis of the proximal femur can subsequently develop. Avascular necrosis is cell death secondary to metabolic disturbances, trauma, adverse effects of certain medications, or sickle cell disease. Avascular necrosis commonly affects the talus, humerus, or tibia in addition to the femoral head. Radiographic images are essential for prompt diagnosis and to minimize negative health outcomes in these patients. However, Salter-Harris I fracture in sickle cell patients can be very challenging due to these patients' vulnerability to bone infections and sickle cell crisis. In this case report, our patient with a history of sickle cell disease and with a diagnosis of Salter-Harris I fracture was treated with surgical intervention as type V, which is discussed in this article, and responded well to treatment. Thus, this case suggests a new approach to managing Salter-Harris I fractures complicated with osteomyelitis in sickle cell patients.

Food insecurity, housing instability, and dietary quality among children with sickle cell disease: Assessment from a single urban center

BACKGROUND

Food insecurity and housing instability, both social determinants of health (SDoH), disproportionately affect economically unstable, under-resourced US communities in which children with sickle cell disease (SCD) live. Association between these SDoH markers and dietary quality among children with SCD is unknown.

PROCEDURES

We assessed a cross-sectional sample of dyadic parent-child patients and young adult patients up to age 21 from one pediatric SCD center. Food insecurity, housing instability, and dietary quality were measured using validated US instruments and a food frequency questionnaire. Better dietary quality was defined using US dietary guidelines. Multivariate regression assessed for associations among dietary quality and food insecurity with or without (±) housing instability and housing instability alone.

RESULTS

Of 100 enrolled participants, 53% were Black and 43% Hispanic; mean age 10.6 ± 5.6 years. Overall, 70% reported less than or equal to one economic instability: 40% housing instability alone and 30% both food insecurity and housing instability. Eighty percent received more than or equal to one federal food assistance benefit. Compared to no economic instability, food insecurity ± housing instability was significantly associated with higher intake of higher dairy and pizza, while housing instability alone was significantly associated with higher dairy intake. Food insecurity ± housing instability was significantly associated with lower intake of whole grains compared to housing instability alone.

CONCLUSIONS

Our sample reported high frequencies of both food insecurity and housing instability; having more than or equal to one SDoH was associated with elements of poorer diet quality. Screening families of children with SCD for food insecurity and housing instability may identify those with potential nutrition-related social needs.

Relationship between disease severity and folate status of children with sickle cell anaemia in Enugu, South East Nigeria

Background

Repeated crises in children with sickle cell anaemia (SCA), which is a manifestation of disease severity, results in depletion of their minimal tissue folate stores, with higher likelihood of folate deficiency. The study aimed to determine the relationship between disease severity and the folate status of children with SCA attending University of Nigeria Teaching Hospital (UNTH), Enugu.

Methods

This was a hospital based, cross-sectional study conducted between September 2018 and March 2019. One hundred participants were recruited, consisting of 50 children having sickle cell crisis and 50 age and gender matched haemoglobin AA genotype controls. Relevant information was documented using a pretested questionnaire. Sickle cell severity score was determined using frequency of crisis, admissions and transfusions in the preceding one year, degree of liver and splenic enlargement, life-time cummulative frequency of specific complications of SCA, leucocyte count and haematocrit.

Results

Folate deficiency was observed in eight percent of the subjects and none of the controls. The difference was not significant (Fisher's exact = 4.167, p=0.117). The odds of being folate deficient was 8.5 times more likely during anaemic crisis than in vaso-occlusive crisis, though not significant (95% C.I 0.05 – 89.750, p = 0.075). The mean SCA severity score was 8.06 ± 3.64, signifying a moderate SCA severity in the study population. There was a no relationship between folate status and severity of SCA (Fisher's exact = 0.054, p = 0.949)

Conclusion

Folate status in children with SCA is not affected by their disease severity. Therefore, there may be no need for additional folate supplementation with increasing severity of sickle cell anaemia.

Mechanisms of Bone Impairment in Sickle Bone Disease

Sickle bone disease (SBD) is a chronic and invalidating complication of Sickle cell disease (SCD), a multisystem autosomal recessive genetic disorder affecting millions of people worldwide. Mechanisms involved in SBD are not completely known, especially in pediatric age. Among the hypothesized pathogenetic mechanisms underlying SBD are bone marrow compensatory hyperplasia and bone ischemic damage, both secondary to vaso-occlusive crisis (VOC), which leads to cell sickling, thus worsening local hypoxia with a negative impact on osteoblast recruitment. Furthermore, the hypoxia is a strong activator of erythropoietin, which in turn stimulates osteoclast precursors and induces bone loss. Hemolysis and iron overload due to a chronic transfusion regimen could also contribute to the onset of bone complications. Vitamin D deficiency, which is frequently seen in SCD subjects, may worsen SBD by increasing the resorptive state that is responsible for low bone mineral density, acute/chronic bone pain, and high fracture risk. An imbalance between osteoblasts and osteoclasts, with a relative decrease of osteoblast recruitment and activity, is a further possible mechanism responsible for the impairment of bone health in SCD. Moreover, delayed pubertal growth spurt and low peak bone mass may explain the high incidence of fracture in SCD adolescents. The aim of this review was to focus on the pathogenesis of SBD, updating the studies on biochemical, instrumental, and biological markers of bone metabolism. We also evaluated the growth development and endocrine complications in subjects affected with SCD.

Plasma Folate Levels in Acutely Ill and Steady State Pediatric Sickle Cell Disease Patients in Ghana

Background

Individuals with sickle cell disease (SCD) are susceptible to infective conditions that predispose them to hemolysis and anemia. Folic acid is recommended as a preventative measure against anemia in SCD patients; however, there is scarce literature on the implications of this practice.

Patients and Methods

Plasma concentrations of folate were measured in acutely ill pediatric SCD patients presenting with malaria or bacteremia and compared with those of SCD patients in steady state, or acutely ill non-SCD patients with confirmed malaria.

Results

The proportion of individuals with high (>45.3 nmol/L) folate concentrations was 29.5% (13/44), 18.2% (8/44), 33.3% (6/18), and 0% in the SCD-malaria, SCD steady state, SCD bacteremia, and the non-SCD malaria groups, respectively. The proportion of SCD patients with high folate levels did not vary significantly at steady state and during confirmed malaria (p = 0.216), and during acute bacteremia (p = 0.20). The median (interquartile range) plasma folate levels were 34.50 (24.40–52.00 nmol/L), 33.40 (15.83–60.85 nmol/L), 30.85 (24.68–39.65 nmol/L), and 13.30 (10.03–17.18 nmol/L), respectively, in the SCD malaria, SCD bacteremia, SCD steady state, and the non-SCD malaria sub-groups. The median folate levels of SCD steady state, SCD malaria, and SCD bacteremia sub-groups differed significantly (p < 0.0001) when compared with non-SCD patients, but the levels in the SCD bacteremia and malaria groups were not significantly different from the SCD steady state group.

Conclusion

Elevated levels of plasma folate were found in a high proportion of pediatric SCD patients. The implications of such elevated folate levels in pediatric SCD patients are unknown but may suggest a need for review of current recommendations for prophylactic doses of folic acid in SCD patients.

Homocysteine is associated with severity of microvasculopathy in sickle cell disease patients

The pathophysiology of sickle cell disease (SCD) includes vasculopathy as well as anaemia. Elevated plasma homocysteine is a risk factor for vascular disease and may be associated with increased risk of vascular complications in SCD patients. In the present study, microvascular characteristics were assessed in the bulbar conjunctiva of 18 paediatric and 18 adult SCD patients, using the non-invasive technique of computer-assisted intravital microscopy. A vasculopathy severity index (SI) was computed to quantify the degree of microvasculopathy in each patient. Plasma homocysteine and several of its determinants [serum folate and vitamin B12, plasma pyridoxal-5'-phosphate (vitamin B6 status) and creatinine (kidney function)] were measured. Age was strongly correlated with microvasculopathy in the SCD patients, with the SI increasing about 0·1 unit per one-year increase in age (P < 0·001). After adjusting for age, gender, B-vitamin status and creatinine, homocysteine concentration was directly correlated with severity index (P < 0·05). Age and homocysteine concentration were independent predictors of microvasculopathy in SCD patients. It remains to be determined whether lowering homocysteine concentrations using appropriate B-vitamin supplements (folate and vitamins B12 and B6) - particularly if started early in life - could ameliorate microvasculopathy and its associated complications in SCD patients.

Folic acid supplementation in children with sickle cell disease: study protocol for a double-blind randomized cross-over trial

Background

Sickle cell disease (SCD) is a genetic disorder which causes dysfunctional red blood cells (RBC) and is thought to increase requirements for folate, an essential B vitamin, due to increased RBC production and turnover in the disease. High-dose supplementation with 1–5 mg/d folic acid, synthetic folate, has been the standard recommendation for children with SCD. There is concern about whether children with SCD need such high doses of folic acid, following mandatory folic acid fortification of enriched grains in Canada, and advancements in medical therapies which extend the average lifespan of RBCs. In animal and human studies, high folic acid intakes (1 mg/d) have been associated with accelerated growth of some cancers, and the biological effects of circulating unmetabolized folic acid (UMFA), which can occur with doses of folic acid ≥ 0.2 mg/d, are not fully understood. The objective of this study is to determine efficacy of, and alterations in folate metabolism from high-dose folic acid in children with SCD during periods of folic acid supplementation versus no supplementation.

Methods

In this double-blind randomized controlled cross-over trial, children with SCD (n = 36, aged 2–19 years) will be randomized to either receive 1 mg/d folic acid, the current standard of care, or a placebo for 12 weeks. After a 12-week washout period, treatments will be reversed. Total folate concentrations (serum and RBC), different folate forms (including UMFA), folate-related metabolites, and clinical outcomes will be measured at baseline and after treatment periods. The sum of the values measured in the two periods will be calculated for each subject and compared across the two sequence groups by means of a test for independent samples for the primary (RBC folate concentrations) and secondary (UMFA) outcomes. Dietary intake will be measured at the beginning of each study period.

Discussion

As the first rigorously designed clinical trial in children with SCD, this trial will inform and assess current clinical practice, with the ultimate goal of improving nutritional status of children with SCD.

Trial registration

ClinicalTrials.govNCT04011345. Registered on July 8, 2019

Effect of High-dose Vitamin A Supplementation in Children With Sickle Cell Disease: A Randomized, Double-blind, Dose-finding Pilot Study

Suboptimal vitamin A status (serum retinol <30 µg/dL) is associated with poor clinical outcomes in children with the hemoglobin-SS disease (HbSS), and supplementation with the recommended daily allowance of retinol is ineffective in improving vitamin A status. In a single-center randomized blinded dose-finding pilot study, we compared vitamin A and nutritional status in children with HbSS to healthy children and explored the impact of high-dose supplementation on the primary outcome serum vitamin A status. Exploratory outcomes included hematologic, nutritional, immunologic, and muscle function status in children with HbSS. A mixed-effects linear regression model evaluated associations between vitamin A dose, serum retinol, and exploratory outcomes. Twenty healthy children participated, and 22 subjects with HbSS were randomized to oral 3000 or 6000 IU/d retinol for 8 weeks; 21 subjects completed all evaluations. Serum retinol, growth, and nutritional status were all suboptimal in HbSS subjects at baseline, and supplementation did not change vitamin A status. Fetal hemoglobin (Δ=2.5, 95% confidence interval [CI], 0.5-4.3), mean corpuscular volume (Δ=2.7, 95% CI, 0.7-4.7), mean corpuscular hemoglobin (Δ=1.4, 95% CI, 0.5-2.3), and mean corpuscular hemoglobin concentration (Δ=0.5, 95% CI, 0.1-0.9) all improved with supplementation. Mild improvements in erythrocyte indices, growth status, and muscle function occurred independent of hydroxyurea use.

Association between MTHFR 677C>T polymorphism and vascular complications in sickle cell disease: A meta-analysis

Sickle cell disease (SCD) is considered as a vascular disease due to its chronic vascular manifestations such as leg ulcers, priapism, acute chest syndrome (ACS), stroke, retinopathy, renal insufficiency, pulmonary hypertension, avascular necrosis of the femoral head (AVNF) and splenic infarction. Emerging evidence has shown that the MTHFR 677C>T variant allele is associated with vascular complications (VC) in patients with SCD; however, results from individual studies are inconclusive. The aim of this meta-analysis is to evaluate the association between the MTHFR 677C>T polymorphism and the susceptibility for VC in SCD patients. Articles published in English were collected from Medline, PubMed, Embase, and Web of Science databases. As a result, 11 studies in different populations including 614 SCD patients with VC, and 559 patients without VC were selected. Meta-analysis in fixed effect model showed that mutant genotypes (CT+TT vs. CC) of the MTHFR 677C>T polymorphism is associated with increased risk of vascular complication (OR=1.81, 95% CI=1.37-2.40, P<0.001). This study did not demonstrate publication bias or between-study heterogeneity. Our meta-analysis establishes that the MTHFR 677C>T polymorphism as a high-penetrant risk factor for VC in SCD patients. Further research is needed to support the clinical utility of MTHFR genetic testing for predicting VC in patients with sickle cell disease.

Dietary intakes and nutritional status of children with sickle cell disease at the Princess Marie Louise Hospital, Accra - a survey

Background

Sickle cell disease (SCD) is a chronic genetic blood disorder common among people of African descent, which places nutritional burden among affected individuals. The aim of the study was to determine the dietary intake and nutritional status of children with SCD.

Method

This was a cross sectional study that involved 120 children with SCD aged 3-12 years at the paediatric outpatient department of Princess Marie Louise Hospital (PML) in Accra. A semi-structured questionnaire was used to take information on participant's demographic characteristics and clinical data were obtained from their medical records. Dietary data were obtained using 24-h dietary recall and food frequency questionnaire. Height and weight were measured for participants and their haemoglobin levels were determined to assess their anaemia status.

Results

Intakes of participants were below recommendations for most nutrients, particularly for calcium and antioxidant vitamins (vitamin C and E). Adequacy of nutrient intake declined with age and children with genotype HbSS had a lower tendency to meet dietary recommendations (aOR = 0.45, 95% CI: 0.18, 1.10; p = 0.084). More than a third of the study children (38%) were malnourished, with older children having a tendency to be malnourished compared to the younger ones. Children with the SS genotype were more likely to be stunted (aOR = 3.48, 95% CI: 1.10, 11.01), compared to other genotypes.

Conclusion

Malnutrition is prevalent among children with SCD and hence there is the need to develop comprehensive management coupling nutritional therapy to medical care to improve their nutritional status. Nutritional management should focus much on calcium-rich foods and antioxidants nutrients particularly vitamin C and E to reduce rapid erythrocyte haemolysis and chronic anaemia.

Discontinuation of Folic Acid Supplementation in Young Patients With Sickle Cell Anemia

Folic acid (FA) is commonly prescribed for patients with sickle cell anemia, but evidence for the efficacy of this practice is lacking. We stopped FA supplementation and measured red blood cell folate levels after discontinuation of FA in 72 patients with clinically severe forms of sickle cell disease. We compared hemoglobin and reticulocyte counts before and after FA discontinuation in 51 of those patients, the majority of whom were on hydroxyurea. No patients had red blood cell folate levels below normal and no significant difference in hemoglobin levels (P=0.18) or reticulocyte counts (P=0.37) was found before and after FA discontinuation.

Epidemiology and treatment of relative anemia in children with sickle cell disease in sub-Saharan Africa

INTRODUCTION

Sickle cell disease (SCD) is the most common inherited hemoglobinopathy in the world, with the majority of cases in sub-Saharan Africa. Concomitant nutritional deficiencies, infections or exposure to environmental toxins exacerbate chronic anemia in children with SCD. The resulting relative anemia is associated with increased risk of strokes, poor cognitive function and impaired growth. It may also attenuate optimal response to hydroxyurea therapy, the only effective and practical treatment option for SCD in sub-Saharan Africa. This review will focus on the epidemiology, clinical sequelae, and treatment of relative anemia in children with SCD living in low and middle-income countries in sub-Saharan Africa. Areas covered: The causes and treatment of relative anemia in children with SCD in sub-Saharan Africa. The MEDLINE database was searched using medical subject headings (MeSH) and keywords for articles regarding relative anemia in children with SCD in sub-Saharan Africa. Expert commentary: Anemia due to nutritional deficiencies and infectious diseases such as helminthiasis and malaria are prevalent in sub-Saharan Africa. Their co-existence in children with SCD increases morbidity and mortality. Therefore, preventing, diagnosing and treating the underlying cause of this relative anemia will improve SCD-related outcomes in children in sub-Saharan Africa.

Nutrient Insufficiencies/Deficiencies in Children With Sickle Cell Disease and Its Association With Increased Disease Severity

BACKGROUND

Sickle cell disease (SCD) is characteristically described as a disease of hemolytic anemia and vaso-occlusive crises (VOCs). However, patients suffer from a multitude of other problems including impaired development, chronic pain, and increased susceptibility to infection. Nutritional deficiency has been implicated as a contributor to these issues.

PROCEDURE

We reported the nutrition status with respect to vitamin D, zinc, B6, B12, folate, and homocysteine serum levels in Canadian children with SCD (n = 91). We also tested for associations between nutrients and markers of disease severity and growth.

RESULTS

Almost half the sample (42%) had multiple nutrient insufficiencies/deficiencies, and a further 27% had a single insufficiency/deficiency. The most common insufficiency/deficiency was zinc in 57% followed by calcidiol (25 dihydroxyvitamin D (25(OH)D)) (52%). Sixteen percent of patients had low vitamin B6 levels, while folate, calcitriol (1,25(OH)D), and homocysteine levels were normal. Increased number of vitamin insufficiencies/deficiencies was associated with increasing disease severity (P = 0.018). Zinc insufficiency/deficiency was significantly associated with an increased number of home pain crises (P = 0.001) and an increased incidence of hospitalizations for VOCs (P = 0.01).

CONCLUSIONS

Our findings show that patients with SCD commonly have multiple nutrient insufficiencies/deficiencies and support the growing evidence for the link between low zinc and increased VOC. It also indicates that increased nutrient insufficiencies/deficiencies are associated with increased disease severity in SCD. Prospective studies with larger samples are needed to further elucidate the relationship between nutrient deficiencies and SCD, and to determine whether nutrient supplementation can improve the disease course.

Guidelines for the diagnosis and treatment of cobalamin and folate disorders

The clinical picture is the most important factor in assessing the significance of test results assessing cobalamin status because there is no 'gold standard' test to define deficiency. Serum cobalamin currently remains the first-line test, with additional second-line plasma methylmalonic acid to help clarify uncertainties of underlying biochemical/functional deficiencies. Serum holotranscobalamin has the potential as a first-line test, but an indeterminate 'grey area' may still exist. Plasma homocysteine may be helpful as a second-line test, but is less specific than methylmalonic acid. The availability of these second-line tests is currently limited. Definitive cut-off points to define clinical and subclinical deficiency states are not possible, given the variety of methodologies used and technical issues, and local reference ranges should be established. In the presence of discordance between the test result and strong clinical features of deficiency, treatment should not be delayed to avoid neurological impairment. Treatment of cobalamin deficiency is recommended in line with the British National Formulary. Oral therapy may be suitable and acceptable provided appropriate doses are taken and compliance is not an issue. Serum folate offers equivalent diagnostic capability to red cell folate and is the first-line test of choice to assess folate status.

Malnutrition in Sickle Cell Anemia: Implications for Infection, Growth, and Maturation

Sickle cell anemia (SCA) is a genetic disease that affects mostly individuals of African and/or Hispanic descent, with the majority of cases in sub-Saharan Africa. Individuals with this disease show slowed growth, delayed sexual maturity, and poor immunologic function. These complications could partly be explained by the state of undernutrition associated with the disease. Proposed mechanism of undernutrition include protein hypermetabolism, decreased dietary intake possibly from interleukin-6-related appetite suppression, increased cardiac energy demand/expenditure, and increased red cell turnover. All the above mechanisms manifest as increased resting energy expenditure. Nutritional intervention utilizing single or multiple nutrient supplementation has led to improved clinical outcome, growth, and sexual maturation. Studies are currently underway to determine the best possible approach to applying nutritional intervention in the management of SCA. Management of SCA will, of necessity, involve a nutritional component, given the sociodemographic distribution of those most affected by the disease, the ease of a nutritional approach, and the wider reach that such an approach will embody.

Association of chromosome damage detected as micronuclei with hematological diseases and micronutrient status

Epidemiological studies reveal strong association between micronutrient deficiencies and development of cancer. Since chromosome breaks and abnormal chromosome segregation, identified as micronuclei (MN), are central to malignant transformation, the influence of micronutrient status upon MN frequency has been the subject of intense research. Motivating this effort is the idea that marginal micronutrient deficiencies lead to allocation of scarce cellular resources towards immediate survival at the expense of maintaining genomic integrity, placing the individual at greater risk for degenerative diseases and cancer in old age. The challenge in identifying an association between individual micronutrients and MN frequency stems from the complexity of human diet, simultaneous presence of multiple micronutrient deficiencies, variable genetic susceptibility and methodological difficulties. A unique model for studying MN in humans is provided by a group of haematological diseases, the chronic haemolytic anaemias associated with high reticulocyte count and absence of splenic function. These disorders may prove valuable for assessing the influence of micronutrient status once the effect of abnormal erythropoiesis on MN formation is adequately understood. Eventually, large population-based studies that can account for the baseline variability in MN frequency, lifestyle and genetic factors may be needed to uncover the DNA-damaging effect of poor diet. Understanding the link between micronutrient status and MN frequency will contribute towards determining optimal micronutrient intake to preserve long-term health.

Nutritional deficiencies in iron overloaded patients with hemoglobinopathies

One of the hallmarks of both sickle cell disease (SCD) and thalassemia major (TM) is accelerated oxidative damage. Decreased antioxidant levels and increased oxidant stress biomarkers are found in both diseases. Although isolated vitamin deficiencies have been reported in TM and nontransfused SCD patients, a comprehensive evaluation of vitamin and trace mineral levels has never been performed in chronically transfused SCD or TM patients. As vitamins and trace minerals may be consumed as a result of chronic oxidative stress; we hypothesized that levels of these compounds would correlate with surrogates of iron overload, hemolysis, and inflammation in chronically transfused patients. Using a convenience sample of our group of chronically transfused patients we studied 43 patients with SCD (17 male, 26 female) and 24 patients with TM (13 male and 11 female). The age range for our patients varied from 1.5 to 31.4 years. Levels of vitamins A, thiamin, B6, B12, C, D, E as well as selenium, zinc, copper, and ceruloplasmin were measured. We found that 40-75% of the patients were deficient in A, C, D and selenium and 28-38% of the patients had low levels of B vitamins and folate. There was little association with iron overload, hemolysis, or inflammation. Although the precise mechanism of these deficiencies is unclear, they may contribute to the morbidity of chronically transfused hemoglobinopathy patients.

Adequacy of Dietary Intake Declines with Age in Children with Sickle Cell Disease

Dietary intake (24-hour recall) was evaluated prospectively over four annual visits in 97 children and adolescents (53 female), aged 1.5 to 18.7 years, with sickle cell disease, type SS. Macro- and micronutrient intakes were compared to Dietary Reference Intakes (DRI) and expressed as %DRI. z scores for height, weight, and body mass index were calculated to assess growth status. Both t tests and Mann-Whitney U tests were used for year 1 comparisons, and longitudinal mixed effects analysis was used for the longitudinal data. Intake of vitamins E and D, folate, calcium, and fiber as %DRI was low for children of all ages. Intake of protein, vitamin C, riboflavin, vitamin B-12, and magnesium was lower by at least 28% DRI in the oldest (aged 14 to 18 years) compared to the youngest children (aged 1 to 3 years), and intake of vitamin A, magnesium, and phosphorus was suboptimal in children older than 9 years. After adjusting for initial age and sex, intake of riboflavin, zinc, calcium, magnesium, and phosphorus declined steeply (8% to 16% DRI annually) across the 3 years. Weight and body mass index z scores also declined over time. Dietary intake was particularly poor in adolescents. Efforts are needed to ensure dietary adequacy in children with sickle cell disease, type SS and to understand the etiology of poor dietary intake.

Bone involvement in sickle cell disease

Bone involvement is the commonest clinical manifestation of sickle cell disease both in the acute setting such as painful vaso-occlusive crises, and as a source of chronic, progressive disability such as avascular necrosis. Management of these problems is often difficult because of the diagnostic imprecision of most laboratory and imaging investigations and because of the lack of evidence for most surgical procedures in sickle cell disease. This review first discusses the acute problems related to bone involvement in sickle cell disease, with particular reference to differentiating infection from infarction, and then describes the long-term effects of sickle cell disease on bone mineral density, growth, and chronic bone and joint damage.

Concentrations of B vitamins and homocysteine in children with sickle cell anemia

BACKGROUND

Elevated concentration of serum homocysteine contributes to thrombosis, a frequent event in patients with sickle cell anemia. We aimed to test whether children with sickle cell anemia have elevated concentrations of serum homocysteine with diminished levels of folate or B vitamins from accelerated blood cell turnover.

METHODS

We conducted a case-control study of children with homozygous sickle cell anemia (n = 17) and unaffected children (n = 11). We measured serum and red blood cell folate, vitamin B6, vitamin B12, and homocysteine concentrations, and assessed micronutrient intake.

RESULTS

Children with sickle cell anemia had concentrations of homocysteine slightly higher than those of unaffected children. They had lower vitamin B6 concentrations and comparable concentrations of folate and vitamin B12. Homocysteine concentration was inversely related to vitamin B12 concentration and was not independently associated with levels of vitamin B6 or folate.

CONCLUSION

Despite comparable intake, children with sickle cell anemia had lower concentrations of vitamin B6 than unaffected children. Larger studies are needed to determine if chronically low serum vitamin B6 concentration contributes to hyperhomocysteinemia in this population.

Vitamin B6 status of children with sickle cell disease

PURPOSE

In vitro, vitamin B(6) has antisickling properties, but the effect of vitamin B status on the health of children with sickle cell disease-SS (SCD-SS) is not well described. The purpose of this study was to assess vitamin B(6) status of children with SCD-SS ages 3 to 20 years and determine its relationship to growth, dietary intake, and disease severity.

PATIENTS AND METHODS

Vitamin B(6) status was assessed by serum pyridoxal 5-phosphate (PLP) concentration in subjects with SCD-SS and by urinary 4-pyridoxic acid (4-PA) concentration in other subjects with SCD-SS and healthy control children. Concentration of PLP was compared with anthropometric measures of growth and nutritional status, dietary intake, hematologic indices, and frequency of SCD-related illness.

RESULTS

The PLP concentration of subjects with SCD-SS was 15.6 +/- 15.2 nmol/L. Seventy-seven percent had a PLP concentration below the deficiency criterion (20 nmol/L) suggested by the Dietary Reference Intakes (1998). Controlling for alkaline phosphatase, age, and gender, PLP concentration was associated positively with weight, body mass index, and arm circumference -scores and negatively with reticulocyte count. Urinary 4-PA was lower in children with SCD-SS versus controls, although 4-PA/creatinine values did not differ between groups.

CONCLUSIONS

Children with SCD-SS had apparently low serum PLP concentrations in the absence of excess vitamin B(6) excretion, suggesting low vitamin B(6) status. Low serum PLP concentration was associated with indicators of poor nutritional status and may be related to increased hemolysis in children with SCD-SS.