Vitamin D supplementation for sickle cell disease

Precision, integrative medicine for pain management in sickle cell disease

Sickle cell disease (SCD) is a prevalent and complex inherited pain disorder that can manifest as acute vaso-occlusive crises (VOC) and/or chronic pain. Despite their known risks, opioids are often prescribed routinely and indiscriminately in managing SCD pain, because it is so often severe and debilitating. Integrative medicine strategies, particularly non-opioid therapies, hold promise in safe and effective management of SCD pain. However, the lack of evidence-based methods for managing SCD pain hinders the widespread implementation of non-opioid therapies. In this review, we acknowledge that implementing personalized pain treatment strategies in SCD, which is a guideline-recommended strategy, is currently fraught with limitations. The full implementation of pharmacological and biobehavioral pain approaches targeting mechanistic pain pathways faces challenges due to limited knowledge and limited financial and personnel support. We recommend personalized medicine, pharmacogenomics, and integrative medicine as aspirational strategies for improving pain care in SCD. As an organizing model that is a comprehensive framework for classifying pain subphenotypes and mechanisms in SCD, and for guiding selection of specific strategies, we present evidence updating pain research pioneer Richard Melzack's neuromatrix theory of pain. We advocate for using the updated neuromatrix model to subphenotype individuals with SCD, to better select personalized multimodal treatment strategies, and to identify research gaps fruitful for exploration. We present a fairly complete list of currently used pharmacologic and non-pharmacologic SCD pain therapies, classified by their mechanism of action and by their hypothesized targets in the updated neuromatrix model.

Sickle cell disease in Gulf Cooperation Council countries: a systematic review

INTRODUCTION

Evidence related to the national burden of Sickle Cell Disease (SCD) in Gulf Cooperation Council (GCC) largely fragmented. Thus, the aim of this study is to systemically review studies from GCC countries to assess the epidemiological profile of SCD.

AREAS COVERED

We searched combinations of key terms in MEDLINE/PubMed, CINAHL, and EMBASE. We selected relevant observational studies reporting the frequency, incidence, prevalence, risk factors, mortality rate, and complications of SCD among the GCC population. Studies restricted to laboratory diagnostic tests, experimental and animal studies, review articles, case reports and series, and conference proceedings and editorials were excluded. A total of 1,347 articles were retrieved, out of which 98 articles were found to be eligible and included in the study. The total number of participants from all the included studies was 3496447. The prevalence of SCD ranged from 0.24%-5.8% across the GCC and from 1.02%-45.8% for the sickle cell trait. Consanguineous marriage was a risk factor for likely giving children affected with hemoglobinopathies.

EXPERT OPINION

The prevalence of SCD and its complications vary among GCC. Because of the high prevalence of SCD and its complications, health authorities should focus on more rigorous prevention and treatment strategies.

Hypothesis: Low Vitamin A and D Levels Worsen Clinical Outcomes When Children with Sickle Cell Disease Encounter Parvovirus B19

Human parvovirus B19 causes life-threatening anemia due to transient red cell aplasia (TRCA) in individuals with sickle cell disease (SCD). Children with SCD experiencing profound anemia during TRCA often require red blood cell transfusions and hospitalization. The prevalence of vitamin deficiencies in SCD is high and deficiencies are associated with respiratory and pain symptoms, but the effects of vitamins on acute infection with parvovirus B19 remain unclear. We performed a clinical study in which 20 SCD patients hospitalized with parvovirus B19 infections (Day 0) were monitored over a 120-day time course to query relationships between vitamins A and D and clinical outcomes. There were significant negative correlations between Day 0 vitamin levels and disease consequences (e.g., red blood cell transfusion requirements, inflammatory cytokines). There were significant positive correlations (i) between Day 0 vitamins and peak virus-specific antibodies in nasal wash, and (ii) between Day 0 virus-specific serum plus nasal wash antibodies and absolute reticulocyte counts. There was a significant negative correlation between Day 0 virus-specific serum antibodies and virus loads. To explain the results, we propose circular and complex mechanisms. Low baseline vitamin levels may weaken virus-specific immune responses to permit virus amplification and reticulocyte loss; consequent damage may further reduce vitamin levels and virus-specific immunity. While the complex benefits of vitamins are not fully understood, we propose that maintenance of replete vitamin A and D levels in children with SCD will serve as prophylaxis against parvovirus B19-induced TRCA complications.

Current Overview on Therapeutic Potential of Vitamin D in Inflammatory Lung Diseases

Inflammatory lung disorders (ILDs) are one of the world's major reasons for fatalities and sickness, impacting millions of individuals of all ages and constituting a severe and pervasive health hazard. Asthma, lung cancer, bronchiectasis, pulmonary fibrosis acute respiratory distress syndrome, and COPD all include inflammation as a significant component. Microbe invasions, as well as the damage and even death of host cells, can cause and sustain inflammation. To counteract the negative consequences of irritants, the airways are equipped with cellular and host defense immunological systems that block the cellular entrance of these irritants or eliminate them from airway regions by triggering the immune system. Failure to activate the host defense system will trigger chronic inflammatory cataracts, leading to permanent lung damage. This damage makes the lungs more susceptible to various respiratory diseases. There are certain restrictions of the available therapy for lung illnesses. Vitamins are nutritional molecules that are required for optimal health but are not produced by the human body. Cholecalciferol (Vitamin D) is classified as a vitamin, although it is a hormone. Vitamin D is thought to perform a function in bone and calcium homeostasis. Recent research has found that vitamin D can perform a variety of cellular processes, including cellular proliferation; differentiation; wound repair; healing; and regulatory systems, such as the immune response, immunological, and inflammation. The actions of vitamin D on inflammatory cells are dissected in this review, as well as their clinical significance in respiratory illnesses.

Femur Fracture in a Premature Infant: An Unusual Association of Sickle Cell Disease with Osteogenesis Imperfecta

Patient: Female, 1-year-old

Final Diagnosis: Sickle cell anaemia

Symptoms: Fracture

Medication: —

Clinical Procedure: —

Specialty: Hematology • Pediatrics and Neonatology

Current and novel therapies for the prevention of vaso-occlusive crisis in sickle cell disease

Individuals with sickle cell disease (SCD) are living further into adulthood in high-resource countries. However, despite increased quantity of life, recurrent, acute painful episodes cause significant morbidity for affected individuals. These SCD-related painful episodes, also referred to as vaso-occlusive crises (VOCs), have multifactorial causes, and they often occur as a result of multicellular aggregation and vascular adherence of red blood cells, neutrophils, and platelets, leading to recurrent and unpredictable occlusion of the microcirculation. In addition to severe pain, long-term complications of vaso-occlusion may include damage to muscle and/or bone, in addition to vital organs such as the liver, spleen, kidneys, and brain. Severe pain associated with VOCs also has a substantial detrimental impact on quality of life for individuals with SCD, and is associated with increased health care utilization, financial hardship, and impairments in education and vocation attainment. Previous treatments have targeted primarily SCD symptom management, or were broad nontargeted therapies, and include oral or parenteral hydration, analgesics (including opioids), nonsteroidal anti-inflammatory agents, and various other types of nonpharmacologic pain management strategies to treat the pain associated with VOC. With increased understanding of the pathophysiology of VOCs, there are several new potential therapies that specifically target the pathologic process of vaso-occlusion. These new therapies may reduce cell adhesion and inflammation, leading to decreased incidence of VOCs and prevention of end-organ damage. In this review, we consider the benefits and limitations of current treatments to reduce the occurrence of VOCs in individuals with SCD and the potential impact of emerging treatments on future disease management.

Vitamin D Supplementation Improves Health-Related Quality of Life and Physical Performance in Children with Sickle Cell Disease and in Healthy Children

INTRODUCTION

No study determined if vitamin D supplementation improves health-related quality of life (HRQL) using pediatric Patient-Reported Outcomes Measurement Information System or physical functioning in type SS sickle cell disease (HbSS).

METHOD

Subjects with HbSS (n = 21) and healthy subjects (n = 23) were randomized to daily oral doses (4,000 vs. 7,000 IU) of cholecalciferol (vitamin D3) and evaluated at 6 and 12 weeks for changes in serum 25 hydroxyvitamin D (25(OH)D), HRQL, and physical functioning.

RESULTS

In subjects with HbSS, significant reductions in pain, fatigue, and depressive symptoms and improved upper-extremity function were observed. In healthy subjects, significant reductions in fatigue and improved upper-extremity function were observed. Significant improvements in peak power and dorsiflexion isometric maximal voluntary contraction torques were observed in both groups. In subjects with HbSS, improved plantar flexion isometric maximal voluntary contraction torques were observed. Both groups saw significant improvement in their total Bruininks-Oseretsky Test of Motor Proficiency score.

DISCUSSION

Daily high-dose vitamin D supplementation for African American children with and without HbSS improved HRQL and physical performance.

Vitamin D supplementation for sickle cell disease

BACKGROUND

Sickle cell disease (SCD) is a genetic chronic haemolytic and pro-inflammatory disorder. With increased catabolism and deficits in energy and nutrient intake, individuals with SCD suffer multiple macro- and micro-nutritional deficiencies, including vitamin D deficiency. This is an update of a previous review.

OBJECTIVES

To investigate the effects of vitamin D supplementation in children and adults with SCD and to compare different dose regimens. To determine the effects of vitamin D supplementation on general health (e.g. growth status and health-related quality of life), on musculoskeletal health (including bone mineral density, pain crises, bone fracture and muscle health), on respiratory health (including lung function, acute chest syndrome, acute exacerbation of asthma and respiratory infections) and the safety of vitamin D supplementation.

SEARCH METHODS

We searched the Cochrane Haemoglobinopathies Trials Register, compiled from electronic database searches and handsearching of journals and conference abstract books. Date of last search: 19 March 2020. We also searched database such as PubMed, clinical trial registries and the reference lists of relevant articles and reviews. Date of last search: 14 January 2020.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-RCTs comparing oral administration of any form of vitamin D supplementation at any dose and for any duration to another type or dose of vitamin D or placebo or no supplementation in people with SCD, of all ages, gender, and phenotypes.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted the data and assessed the risk of bias of the included studies. They used the GRADE guidelines to assess the quality of the evidence.

MAIN RESULTS

Vitamin D versus placebo One double-blind RCT (n = 39) compared oral vitamin D3 (cholecalciferol) supplementation (20 participants) to placebo (19 participants) for six weeks. Only 25 participants completed the full six months of follow-up. The study had a high risk of bias due to incomplete outcome data, but a low risk of bias for randomisation, allocation concealment, blinding (of participants, personnel and outcome assessors) and selective outcome reporting; and an unclear risk of other biases. Vitamin D supplementation probably led to higher serum 25(OH)D levels at eight weeks, mean difference (MD) 29.79 (95% confidence interval (CI) 26.63 to 32.95); at 16 weeks, MD 12.67 (95% CI 10.43 to 14.90); and at 24 weeks, MD 15.52 (95% CI 13.50 to 17.54) (moderate-quality evidence). There was little or no difference in adverse events (tingling of lips or hands) between the vitamin D and placebo groups, risk ratio 3.16 (95% CI 0.14 to 72.84) (low-quality evidence). Vitamin D supplementation probably caused fewer pain days compared to the placebo group at eight weeks, MD -10.00 (95% CI -16.47 to -3.53) (low-quality evidence), but probably led to a lower (worse) health-related quality of life score (change from baseline in physical functioning PedsQL scores); at both 16 weeks, MD -12.56 (95% CI -16.44 to -8.69) and 24 weeks, MD -12.59 (95% CI -17.43 to -7.76), although this may not be the case at eight weeks (low-quality evidence). Vitamin D supplementation regimens compared Two double-blind RCTs (83 participants) compared different regimens of vitamin D. One RCT (n = 62) compared oral vitamin D3 7000 IU/day to 4000 IU/day for 12 weeks, while the second RCT (n = 21) compared oral vitamin D3 100,000 IU/month to 12,000 IU/month for 24 months. Both RCTs had low risk of bias for blinding (of participants, personnel and outcome assessors) and incomplete outcome data, but the risk of selective outcome reporting bias was high. The bias from randomisation and allocation concealment was low in one study but not in the second. There was an unclear risk of other biases. When comparing oral vitamin D 100,000 IU/month to 12,000 IU/month, the higher dose may have resulted in higher serum 25(OH)D levels at one year, MD 16.40 (95% CI 12.59 to 20.21) and at two years, MD 18.96 (95% CI 15.20 to 22.72) (low-quality evidence). There was little or no difference in adverse events between doses (low-quality evidence). There were more episodes of acute chest syndrome in the high-dose group, at one year, MD 0.27 (95% CI 0.02 to 0.52) but there was little or no difference at two years, MD 0.09 (95% CI -0.04 to 0.22) (moderate-quality evidence). At one year and two years there was also little or no difference between the doses in the presence of pain (moderate-quality evidence) or forced expiratory volume in one second % predicted. However, the high-dose group had lower values for % predicted forced vital capacity at both one and two years, MD -7.20% predicted (95% CI -14.15 to -0.25) and MD -7.10% predicted (95% CI -14.03 to -0.17), respectively. There were little or no differences between dose regimens in the muscle health of either hand or the dominant hand. The study comparing oral vitamin D3 7000 IU/day to 4000 IU/day (21 participants) did not provide data for analysis, but median serum 25(OH)D levels were reported to be lower in the low-dose group at both six and 12 weeks. At 12 weeks the median serum parathyroid hormone level was lower in the high-dose group.

AUTHORS' CONCLUSIONS

We included three RCTs of varying quality. We consider that the current evidence presented in this review is not of sufficient quality to guide clinical practice. Until further evidence becomes available, clinicians should consider the relevant existing guidelines for vitamin D supplementation and dietary reference intakes for calcium and vitamin D. Well-designed RCTs of parallel design, are required to determine the effects and the safety of vitamin D supplementation as well as to assess the relative benefits of different doses in children and adults with SCD.

Development of Algorithm for Clinical Management of Sickle Cell Bone Disease: Evidence for a Role of Vertebral Fractures in Patient Follow-up

Sickle-cell disease (SCD) is a worldwide distributed hemoglobinopathy, characterized by hemolytic anemia associated with vaso-occlusive events. These result in acute and chronic multiorgan damage. Bone is early involved, leading to long-term disability, chronic pain and fractures. Here, we carried out a retrospective study to evaluate sickle bone disease (SBD) in a cohort of adults with SCD. We assessed bone density, metabolism and turnover. We also evaluated the presence of fractures and the correlation between SCD severity and skeletal manifestations. A total of 71 patients with SCD were analyzed. The mean age of population was 39 ± 10 years, 56% of which were females. We found osteoporosis in a range between 7% and 18% with a high incidence of vertebral fractures. LDH and AST were predictive for the severity of vertebral fractures, while bone density was not. Noteworthy, we identified -1.4 Standard Deviations T-score as the cutoff for detecting the presence of fractures in patients with SCD. Collectively our data allowed us to develop an algorithm for the management of SBD, which may be useful in daily clinical practice to early intersect and treat SBD.

The Evolving Pharmacotherapeutic Landscape for the Treatment of Sickle Cell Disease

Sickle cell disease (SCD) is an extremely heterogeneous disease that has been associated with global morbidity and early mortality. More effective and inexpensive therapies are needed. During the last five years, the landscape of the pharmacotherapy of SCD has changed dramatically. Currently, 54 drugs have been used or under consideration to use for the treatment of SCD. These fall into 3 categories: the first category includes the four drugs (Hydroxyurea, L-Glutamine, Crizanlizumab tmca and Voxelotor) that have been approved by the United States Food and Drug Administration (FDA) based on successful clinical trials. The second category includes 22 drugs that failed, discontinued or terminated for now and the third category includes 28 drugs that are actively being considered for the treatment of SCD. Crizanlizumab and Voxelotor are included in the first and third categories because they have been used in more than one trial. New therapies targeting multiple pathways in the complex pathophysiology of SCD have been achieved or are under continued investigation. The emerging trend seems to be the use of multimodal drugs (i.e. drugs that have different mechanisms of action) to treat SCD similar to the use of multiple chemotherapeutic agents to treat cancer.

Height-corrected low bone density associates with severe outcomes in sickle cell disease: SCCRIP cohort study results

Low bone mineral density (BMD) disproportionately affects people with sickle cell disease (SCD). Growth faltering is common in SCD, but most BMD studies in pediatric SCD cohorts fail to adjust for short stature. We examined low BMD prevalence in 6- to 18-year-olds enrolled in the Sickle Cell Clinical Research and Intervention Program (SCCRIP), an ongoing multicenter life span SCD cohort study initiated in 2014. We calculated areal BMD for chronological age and height-adjusted areal BMD (Ht-aBMD) z scores for the SCCRIP cohort, using reference data from healthy African American children and adolescents enrolled in the Bone Mineral Density in Childhood Study. We defined low BMD as Ht-aBMD z scores less than or equal to -2 and evaluated its associations with demographic and clinical characteristics by using logistic regression analyses. Of the 306 children and adolescents in our study cohort (mean age, 12.5 years; 50% female; 64% HbSS/Sβ0-thalassemia genotype; 99% African American), 31% had low areal BMD for chronological age z scores and 18% had low Ht-aBMD z scores. In multivariate analyses, low Ht-aBMD z scores associated with adolescence (odds ratio [OR], 7.7; 95% confidence interval [CI], 1.94-30.20), hip osteonecrosis (OR, 4.0; 95% CI, 1.02-15.63), chronic pain (OR, 10.4; 95% CI, 1.51-71.24), and hemoglobin (OR, 0.74; 95% CI, 0.57-0.96). Despite adjusting for height, nearly 20% of this pediatric SCD cohort still had very low BMD. As the SCCRIP cohort matures, we plan to prospectively evaluate the longitudinal relationship between Ht-aBMD z scores and markers of SCD severity and morbidity.

Asymmetric Dimethylarginine Levels and Its Correlation to Cerebral Blood Flow in Children with Sickle Cell Anemia

Asymmetric dimethylarginine (ADMA) level may play a role in the pathogenesis of cerebrovascular stroke in Children with Sickle Cell Anemia (SCA). To assess the plasma level of ADMA in children with SCA and its correlation to cerebral blood flow. This is a cross sectional study was carried out on 30 children with homozygous SCA under follow up in the Out Patients Clinic, Pediatric Department at Tanta University Hospital and 30 healthy children as a control group. Both groups had undergone the following investigations: Complete blood count, lactate dehydrogenase enzyme, and plasma level of ADMA by a commercial ADMA ELISA Kit. Trans-cranial Doppler were done for both groups. ADMA plasma level was significantly higher in-patient group in comparison to the control group (p < 0.001), with a mean value 1.43 ± 0.20 μmol/l, 0.48 ± 0.16 μmol/l respectively. The time-averaged mean maximum velocities for middle cerebral artery, anterior cerebral artery, inferior cerebral artery and posterior cerebral artery were significantly different between patient and control group, p < 0.05. Trans-cranial Doppler data revealed that, 86.7% of patients have low velocity (< 70 cm/s) and 13.3% having very low velocity (< 10 cm/s) while control group have normal velocity. There was a significant negative correlation between ADMA plasma levels and cerebral blood flow. Elevated ADMA levels may have a role in the pathogenesis of the decreased cerebral blood flow in children with SCA.

Randomized phase 2 trial of monthly vitamin D to prevent respiratory complications in children with sickle cell disease

In sickle cell disease, respiratory infection and asthma may lead to respiratory complications that are a leading cause of morbidity and mortality. Vitamin D has anti-infective and immunomodulatory effects that may decrease the risk for respiratory infections, asthma, and acute chest syndrome. We conducted a randomized double-blind active-controlled clinical trial to determine whether monthly oral vitamin D₃ can reduce the rate of respiratory events in children with sickle cell disease. Seventy sickle cell subjects, ages 3-20 years, with baseline records of respiratory events over 1 year before randomization, underwent screening. Sixty-two subjects with 25-hydroxyvitamin D levels of 5-60 ng/mL were randomly assigned to oral vitamin D₃ (100 000 IU or 12 000 IU, n = 31 each) under observed administration once monthly for 2 years. The primary outcome was the annual rate of respiratory events (respiratory infection, asthma exacerbation, or acute chest syndrome) ascertained by the use of a validated questionnaire administered biweekly. Analysis included 62 children (mean age of 9.9 years, 52% female, and predominantly with homozygous HbS disease [87%]) with mean baseline 25-hydroxyvitamin D of 14.3 ng/mL. The annual rates of respiratory events at baseline and intervention years 1 and 2 were 4.34 ± 0.35, 4.28 ± 0.36, and 1.49 ± 0.37 (high dose) and 3.91 ± 0.35, 3.34 ± 0.37, and 1.54 ± 0.37 (standard dose), respectively. In pediatric patients with sickle cell disease, 2-year monthly oral vitamin D₃ was associated with a >50% reduction in the rate of respiratory illness during the second year (P = .0005), with similar decreases associated with high- and standard-dose treatment. This trial was registered at www.clinicaltrials.gov as #NCT01443728.

Rheumatic Manifestations of Haemoglobinopathies

PURPOSE OF THE REVIEW

To provide a clinically useful literature review on the rheumatic manifestations of haemoglobinopathies, critically analysing the literature from the past 5 years.

RECENT FINDINGS

There are limited new data to guide the management of rheumatic manifestations of haemoglobinopathies. Data further confirm the wide spectrum of potential rheumatic/MSK involvement in haemoglobinopathies, which poses both a diagnostic and therapeutic challenge. Inflammatory arthritis may be more common than previously believed. Steroid therapy by any route of administration can provocate a potential life-threatening vaso-occlusive crisis. Vitamin D deficiency is common. There are limited data to guide the drug treatment of reduced bone density in haemoglobinopathies. There have been a number of studies examining pain in sickle cell anaemia. Plasma levels of Klotho may represent a novel biomarker in patients with β-Thalassemia. There are little new data on the rheumatic manifestations in haemoglobinopathies and future high-quality research is needed.

Response to Long-term Vitamin D Therapy for Bone Disease in Children With Sickle Cell Disease

Patients with sickle cell disease (SCD) are at risk for bone fragility from multiple factors including vitamin D deficiency. To date, no studies have evaluated the efficacy and safety of long-term vitamin D therapy for bone disease in children with SCD. We report a cohort of 4 children with SCD found to have severe vitamin D deficiency, secondary hyperparathyroidism, and abnormal bone mineral density treated with monthly high-dose oral cholecalciferol over 2 years. All patients exhibited a positive response to therapy without hypervitaminosis D or hypercalcemia. Further studies are needed to standardize guidelines for optimal vitamin D dosing and prevention of toxicity.

Prevalence of Vitamin D Deficiency Varies Widely by Season in Canadian Children and Adolescents with Sickle Cell Disease

Sickle cell disease (SCD) is an inherited disorder caused by a variant (rs334) in the β-globin gene encoding hemoglobin. Individuals with SCD are thought to be at risk of vitamin D deficiency. Our aim was to assess serum 25-hydroxyvitamin D (25OHD) concentrations, estimate deficiency prevalence, and investigate factors associated with 25OHD concentrations in children and adolescents with SCD attending BC Children's Hospital in Vancouver, Canada. We conducted a retrospective chart review of SCD patients (2-19 y) from 2012 to 2017. Data were available for n = 45 patients with n = 142 25OHD measurements assessed using a EUROIMMUN analyzer (EUROIMMUN Medizinische Labordiagnostika AG, Lübeck, Germany). Additional data were recorded, including age, sex, and season of blood collection. Linear regression was used to measure associations between 25OHD concentration and predictor variables. Overall, mean ± SD 25OHD concentration was 79 ± 36 nmol/L; prevalence of low 25OHD concentrations (<30, <40, and <75 nmol/L) was 5%, 17% and 50%, respectively. Mean 25OHD concentrations measured during Jul-Sep were higher (28 (95% confidence interval CI: 16-40) nmol/L higher, P < 0.001) compared to Jan-Mar. Vitamin D deficiency rates varied widely by season: Based on 25OHD <30 nmol/L, prevalence was 0% in Oct-Dec and 6% in Jan-Mar; based on <40 nmol/L, prevalence was 0% in Oct-Dec and 26% in Jan-Mar.

Vitamin D deficiency and anemia risk in children: a review of emerging evidence

There has been renewed scientific interest in the sequelae of vitamin D deficiency, given the emerging evidence on the diverse biologic functions of vitamin D, besides its fundamental role in bone and mineral metabolism. For the past decade, the evidence in the medical literature pointing to a relationship between anemia risk and vitamin D deficiency has been accumulating. This paper critically reviews the current evidence linking vitamin D deficiency to anemia risk in children. The synthesized evidence indicates that the studies, which were preponderantly conducted among the adult population, not only reported a bidirectional relationship between vitamin D deficiency and anemia but also showed a racial effect. In studies conducted among children, similar results were reported. Although the causal association of vitamin D deficiency with anemia risk (especially iron-deficiency anemia) remains debatable, the noncalcemic actions of the vitamin and its analogs hold prospects for several novel clinical applications. There is, however, unanimity in many reports suggesting that vitamin D deficiency is directly associated with anemia of chronic disease or inflammation. Despite the advances in unraveling the role of vitamin D in iron homeostasis, further research is still required to validate causality in the relationship between vitamin D deficiency and anemia, as well as to determine its optimal dosing, the ideal recipients for therapeutic intervention, and the preferred analogs to administer.