Zinc and anthropometry in sickle cell disease: Comparison between two genotypes (SS and SC hemoglobinopathies)

Anuoluwa Abisola Alaka; Olubunmi Olayemi Alaka; Ayobola Abolape Iyanda

doi:10.4103/jihs.jihs_6_22

ORIGINAL ARTICLE

Year : 2022 | Volume : 10 | Issue : 2 | Page : 60-66

Zinc and anthropometry in sickle cell disease: Comparison between two genotypes (SS and SC hemoglobinopathies)

Anuoluwa Abisola Alaka¹, Olubunmi Olayemi Alaka², Ayobola Abolape Iyanda¹
¹ Department of Chemical Pathology, College of Health Sciences, Ladoke Akintola University of Technology, Osogbo, Nigeria
² Department of Medical Microbiology and Parasitology, Obafemi Awolowo University Teaching Hospital, Ile-Ife, Nigeria

Date of Submission	23-Aug-2022
Date of Decision	02-Nov-2022
Date of Acceptance	03-Nov-2022
Date of Web Publication	16-May-2023

Correspondence Address:
Dr. Ayobola Abolape Iyanda
Department of Chemical Pathology, College of Health Sciences, Ladoke Akintola University of Technology, Osogbo
Nigeria

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jihs.jihs_6_22

Abstract

Introduction: Homozygous rather than heterozygous sickle cell disease (SCD) is considered the more severe form of the disorder. While some markers have been used successfully to distinguish between the two with respect to disease severity, the role of other markers remains either inconclusive (e.g., nitric oxide) or ambiguous (e.g., anthropometry). The objective of the study was to provide information about possible variations in anthropometry and zinc (Zn) levels among SS and SC patients in Osun State, Nigeria. Materials and Methods: Adult participants enrolled consisted of 34 SS hemoglobinopathy (also known as HbSS); 32 SC hemoglobinopathy (commonly referred to as HbSC) patients and 32 with HbAA as control. Serum Zn estimation was done by atomic absorption spectrophotometry. Anthropometry (body weight, standing height, body mass index [BMI], head and mid-upper-arm circumferences [MUACs]) was determined using standard procedures. Data were analyzed with analysis of variance and Pearson correlation coefficient. P < 0.05 was considered statistically significant. Results: All anthropometric parameters were significantly lower for SCD patients compared with control, but only body weight was significantly different when HbSS and HbSC were compared. Serum Zn status of control was higher than those of SCD patients, with HbSS values being more significantly lower than those of HBSC. Among the HbSS as well as HbSC patients, there was a positive correlation between BMI and Zn as well as between HC and MUAC. Conclusion: Results of the study indicate that while the Zn status of HbSS and HbSC were significantly different, most of the anthropometric parameters were not significantly different.

Keywords: Body mass index, head circumference, mid-upper-arm circumference, SC hemoglobinopathy, SS hemoglobinopathy, zinc

How to cite this article:
Alaka AA, Alaka OO, Iyanda AA. Zinc and anthropometry in sickle cell disease: Comparison between two genotypes (SS and SC hemoglobinopathies). J Integr Health Sci 2022;10:60-6

How to cite this URL:
Alaka AA, Alaka OO, Iyanda AA. Zinc and anthropometry in sickle cell disease: Comparison between two genotypes (SS and SC hemoglobinopathies). J Integr Health Sci [serial online] 2022 [cited 2023 Jun 4];10:60-6. Available from: https://www.jihs.in/text.asp?2022/10/2/60/377153

Introduction

Sickle cell disease (SCD) is a common disorder in sub-Saharan Africa. It is an inherited hematological disease characterized by chronic hemolytic anemia, persistent infections, musculoskeletal abnormalities, and growth difficulties.^[1],[2] Altered zinc status is another abnormal feature of the disease. Of the group of hemoglobinopathies that constitute SCD, SS hemoglobinopathy (also known as HbSS) is the most frequent and severe form, while the heterozygous form, i.e., SC hemoglobinopathy (also referred to as HbSC), is considered the mild form of the disease.^[3],[4] A number of clinical manifestations and laboratory indices have been helpful in defining/distinguishing the degree of severity among the wide spectrum of sickle cell syndromes (e.g., SS hemoglobinopathy (HbSS), SC hemoglobinopathy (HbSC) and hemoglobin Sβ thalassemia [HbSβ^thal]), there are some others (e.g., anthropometry) that still remain ambiguous.

It was recognized that Zn and packed cell volume (PCV) content were more severely depleted in individuals with HbSS than HbSC. Yet, in the same experimental setting, nitric oxide (NO) level of individuals with HbSS was not significantly different from that of heterozygous SCD-HbSC. NO results seem to contract the common assumption that HbSS is more severe than HbSC due to the lack of significant difference when NO values of both (HbSS, HbSC) were compared. This means that the widely held view that HbSS is a more severe form of the disease compared with HbSC may not be evidently proven with every parameter used for the assessment/management of SCD. In other words, from the results of NO, it can be assumed that some disease markers may not be suitable to differentiate the degree of severe presentations of the various genotypes of SCD.

Aside clinical and biochemical features, other biomarkers which are affected by the disease include those of hematological, inflammatory, and endothelial function.^[5] Yet, Da Guarda et al.^[5] identified that HbSS more than HbSC patients exhibited the most prominent anemia, hemolysis, leukocytosis, and inflammation compared with HbSC, whereas HbSC patients had significantly higher lipid levels compared with HbSS. Anthropometry is another important parameter for the assessment of SCD, but there is a dearth of data on the comparative evaluation of anthropometry among HbSS and HbSC individuals in Osun State, Nigeria. Meanwhile, there is the possibility that due to the influence of PCV, Zn, and NO or its precursor on anthropometry,^[6],[7],[8] as well as the significant association between anthropometry and these parameters, it is not implausible that there may be significant differences in the anthropometry of both genotypic forms of SCD. Access to such information may have significant implications in broadening our understanding of the pathophysiology of abnormal anthropometry of SCD. The objective of the study was to investigate the anthropometry of SCD patients and relate it with Zn, which in earlier reports has been correlated with growth status in many categories of healthy and diseased individuals.^{[9],[10],[11]} In addition, the anthropometry of the two genotypes of SCD (HbSS/HbSC) will be compared.

Materials and Methods

Study design

This study was a comparative cross-sectional study.

Ethical consideration

Ethical approval for the study was obtained from the Osun State Ministry of Health, Osogbo, Osun State. Informed consent was sought and obtained from all study participants. Confidentiality of information obtained was assured to all participants and maintained.

Study sites

Hematology and outpatient clinics in Obafemi Awolowo University Teaching Hospital (UTH) Complex Ile-Ife
Wesley Guild Hospital Ilesha
Osun State UTH Osogbo
Other hospitals under the Osun State Hospitals Management Board (OSHMB) in Osun state, Nigeria.

Sampling technique/sample size

Multistage random sampling technique was adopted. The sample size was calculated using the Cochrane formula: n = z²pq/d²

where n = the minimum required sample size in a population >10,000, z = the standard normal deviation (1.96), p = the proportion in the target population or prevalence, q = the proportion of failure (1 − p), d = the degree of accuracy desired (precision), tolerable margin of error, expected difference.

z = 95% (1.96), P = 2% (0.02)

q = 1 − 0.02 = 0.98, d = 5% (0.05)

Hence, n = (1.96)² × 0.02 × 0.98/(0.05)²

Minimum sample size = 30^[12]

Participant selection/Exclusion and inclusion criteria

Enrolled for the study were a total of 98 adult participants of both sexes (male and female), consisting of 66 patients with SCD and 32 individuals without the disease that served as the control group. They were based in Osun state. The state is situated in the tropical rain forest zone. It covers an area of approximately 14,875 km² and lies between latitude 7° 30′ 0″ N and longitude 4° 30′ 0″ E, with a population of 4.6 million people as of 2016, that consisting of people in low, medium, and high socioeconomic status. The proportion of the disease is 2/100.

Adequate history, detailed medical examination, and laboratory investigation were carried out on these participants. All participants were adequately briefed on the objectives of the study in order to obtain their consent. Only apparently healthy adults with well-established genotype status confirmed by hemoglobin electrophoresis (using cellulose acetate paper) were included in the study. The test groups consisted of individuals with HbSS and HbSC genotypes, while the control group was individuals with normal hemoglobin, i.e., HBAA. Excluded from the study were individuals (SCD patients and controls) transfused with whole blood or blood products within the preceding 3 months before the study. Pregnancy and the presence of renal disease were other exclusion criteria applied during the selection of participants for the study. Also excluded were individuals on Zn supplementation, those placed on Zn-containing drugs or being administered any drug capable of modulating Zn metabolism as well as those with body temp >37°C; conditions such as acute respiratory infection, malaria, diarrhea, or other clinical conditions known to affect plasma Zn are associated with pyrexia as well as metabolic Zn disturbances. Those that had other chronic illnesses that can affect physical growth, such as bronchial asthma, congenital heart disease, chronic renal failure, diabetes mellitus, and malignancies, were exempted. Controls had no evidence of chronic disease, including protein-energy malnutrition. All participants with postural deformities that affect height were excluded from the study.

Questionnaire and anthropometry measurement

Pretested questionnaires were administered to all participants for the collection of age, gender, area of residence, anthropometric measurements, signs, and symptoms of diseases. The weight (in kilograms) of each participant was taken, with participants in their clothes made of light fabric, barefoot, holding onto nothing. A normal bathroom weighing standing scale (Hana, Model: 9011, China) was used, and recordings were made to the nearest 0.5 kg. Standing height in centimeters (cm) was obtained using a stadiometer (Everich, Model: ZT-160, Nanjing, China). Measurement was without shoes, both feet flat on the ground and apposed at the medial malleoli, and made to the nearest 0.5 cm. The body mass index (BMI) was calculated by the formula: BMI = Weight (kg)/height (m²). Head and mid-upper-arm circumferences were obtained. The head circumference was measured to the nearest 0.1 cm with a nonstretchable tape using the glabella and the occiput as the landmarks.^[13]

Specimen handling and estimation of serum zinc

Participants ate at least 4 h before blood samples were collected (to avoid using fasting blood, which may affect the serum Zn). During starvation, there is the release of Zn from muscle tissues that are catabolized, and this can result in transient, seemingly paradoxical elevations of serum Zn and hence give a higher concentration.^[14] Three millimeters of the blood sample was dispensed into a sterile plain bottle, allowed to clot, and then centrifuged (Bucket centrifuge: Uniscope laboratory centrifuge, Model SM112, Surgifriend Medicals, East Street Okehampton, England) at 2000 × g for 5 min to obtain clear nonhemolysed serum. The decanted serum samples were transferred into sterile labeled plain bottles and stored frozen at −20°C before the time of analyses. The apparatus had been washed clean using 10% nitric acid and thoroughly rinsed with deionized water to prevent likely Zn contamination. Serum Zn level was estimated using the atomic absorption spectrometric method, (Analyst 400, Perkin Elmer, Singapore) was used for this purpose.

Statistical analyses

Statistical analysis was performed on data generated using the Statistical Package for the Social Sciences (SPSS) version 20.0 (IBM Corporation, Armonk, NY, USA). The measures of location were determined for serum Zn level and anthropometry. Data were summarized as mean ± standard deviation. Statistical significance was assessed using one-way analysis of variance. Where there was a significant difference within means, post hoc test was applied to determine where the level of significance occurred. Pearson's correlation coefficient was used to determine the association between variables. Differences between values were considered statistically significant, where the probability was <0.05 (P < 0.05).

Results

Stated below are the results of the study in [Table 1], [Table 2], [Table 3], [Table 4]. Anthropometry and serum Zn levels are presented in [Table 1]. There were significant differences in the body weight, standing height, BMI, mid-upper-arm circumference (MUAC), and head circumference of the three categories of study participants (HbAA; HbSS; HbSC). All the anthropometric indices of control (HbAA) were significantly higher than those of SCD patients. While standing height, MUAC, head circumference, and BMI of HbSS were not significantly different from those of HbSC but body weight of HbSS was significantly lower than HbSC. Serum Zn status of control was higher than those of SCD patients, with HbSS values being more significantly lower than those of HBSC.

Table 1: Serum zinc and anthropometric indices of control (HbAA) and sickle cell disease patients (HbSC and HbSS)

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Table 2: Pearson correlation of anthropometry and zinc among control (HbAA) participants

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Table 3: Pearson correlation of anthropometry and serum zinc of SC patients

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Table 4: Pearson correlation of anthropometry and zinc among HbSS participants

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A correlation study revealed that a significant relationship existed between MUAC and BMI, as well as head circumference among the control. Among the HbSS as well as HbSC patients, there was a positive correlation between BMI and Zn as well as between head circumference and MUAC.

Discussion

There are various possible causes for the significant lower levels of serum Zn recorded among SCD (HbSS and HbSC) patients compared with control (HbAA). Depletion in serum Zn level of homozygous and heterozygous SCD patients compared with those with normal genotype can be as a result of insufficient intake-dietary/supplements, enhanced demand and utilization, or elevated urinary excretion occurring from oxidative stress-induced impairment in renal function. In physiologic conditions, absorption of Zn from intestine and continuous shift from the intracellular compartment maintains plasma Zn, but in some diseased states that simple process may be distorted.^[15] For example, metabolic stress occurring from infectious states and acute illnesses which are complications of SCD, are known to increase intracellular shift of Zn into the liver and lowers plasma level even when total body Zn level is unchanged,^[15] this may serve as an alternative explanation for why significantly low level of plasma or serum Zn commonly coexist with SCD.

According to Phebus et al.,^[16] Liu et al.^[17] and Reddy et al.^[18] irrespective of the cause of decreased plasma Zn of SCD conditions, it is commonly associated with decreased linear and skeletal growth, muscle mass, and skeletal maturation. This was in consonant with the results of the study in which significantly low values of BMI, weight, height, head circumference and MUAC were evident in individuals with HbSS and HbSC compared with HbAA. Infections and acute illnesses are more common in the severe form of SCD (HbSS) than the mild form (HbSC), which may indicate why Zn status of individuals with HbSS is lower than those with HbSC.^[19] Meanwhile, significant differences in Zn levels of HbSC and HbSS did not reflect in statistical differences in their anthropometry (except body weight). This suggests other factors probably play modulating roles in the degree of the impact of Zn on different genotypes of SCD.

While insufficient intake may serve as a reasonable cause of depleted Zn in all categories of people, including SCD; Leonard et al.^[20] observed that decreased plasma Zn is common in individuals suffering from SCD, irrespective of the degree of Zn intake or differences in dietary Zn consumption. The fact that the retention time of Zn in the blood is established to be between 2 and 3 days may explain why drastic changes in dietary Zn consumption do not significantly alter plasma Zn level.^[14] Unfortunately, it neither explains why SCD is associated with low Zn status nor does it contribute to the present understanding of the significant differences in Zn levels that exist in the two types of hemoglobinopathies.

The significant decrease in the level of Zn in SCD compared with control should be of great concern due to the vital role of Zn in various physiologic processes. It is an essential element required in the regulation of cell proliferation via its impact on various enzyme systems that influence cell division and proliferation.^[21] The importance of Zn in DNA synthesis is well described in literature; zinc functions by regulating the activity of deoxythymidine kinase as well as maintaining the levels of adenosine 5'-tetraphosphate.^[22] While its influence on cell proliferation is profound, such control is not exerted mainly via alteration in enzyme systems, Zn also affects hormonal regulation of cell division. The pituitary growth hormone (GH)-insulin-like growth factor-1 (IGF-1) axis has been noted for its sensitivity to Zn concentration.^[23] The role of GH and IGF-1 in physical growth and development is well recognized. Co-existence of depleted zinc level with low concentrations of GH and IGF-1 suggest scientific basis for the assumption that growth retardation in zinc depleted SCD patients are related.

The fact that exogenous infusion of GH or IGF-1 levels did not reverse the growth deficit suggests that it is a case of abnormal hormone signaling. It seems that Zn is required for IGF-1 induction of cell proliferation, with its regulatory effects being postreceptor binding.^[23] Essentially, this means that decreased availability of Zn affects membrane signaling systems and intracellular second messengers that coordinate cell proliferation in response to IGF-1. The effect of low Zn levels may transcend hormones of physical growth can be deduced from the reports of Onukwuli et al.^[24] and Fadhil et al.^[25] who implicated Zn deficiency as a possible contributing factor not only to growth retardation but also to delayed sexual maturation of HbSS.

Results revealed that SCD is associated with abnormal anthropometries such as height, weight, BMI, and head circumference, suggesting that SCD causes growth retardation, which may be hypothesized to occur by reduced linear and skeletal growth, muscle mass, and skeletal maturation. Many of the inherent metabolic abnormalities of SCD, such as increased oxidative stress occurring from defective morphology of sickle-shaped erythrocytes, have been linked with depletion in Zn level. The input of excessive generation of reactive oxygen species in the pathophysiology of SCD clearly presented in literature may offer further insights into the role of depleted Zn level in various manifestations of the disease,^[26] especially abnormal anthropometric indices. The development of sickle cell-related complications has been linked with the sustained generation of oxidative stress and impairment of antioxidant defense mechanisms.^[26],[27] Deficiency in Zn concentration may lead to a decrease in the activity of the antioxidant enzyme superoxide dismutase because Zn is an important metallic co-factor of the enzyme, which is necessary for its optimal function.

Meanwhile, unlike the submission of Leonard et al.,^[20] Oredugba and Savage^[28] opined that challenges of SCD such as poor growth may be nutrition related in many categories of SCD patients. As he recognized that in SCD state there was an association between abnormal anthropometry and altered nutritional status on one hand as well as between disease severity and body composition on the other. That energy supply has been recognized to cause a constant perturbation in individuals with sickle cell anemia with its effect on BMI cannot be discounted as the basis for the present result. On the other hand, Thomas et al.^[29] revealed that the significant alterations in anthropometry and Zn status in conditions of SCD could be a result of increased demand from high metabolic rates, reduced absorption, and increased degradation of Zn.^[29] A situation capable of causing hypoxemia and hypoperfusion of tissues which ultimately can lead to tissue impairment and growth retardation as observed in anthropometric measurements such as height, weight, and BMI in the study as well as skeletal maturation and delayed puberty as reported by Beker^[30] and Nandanwar and Kamd^[31] The attendant complications of SCD such as hypoxemia, tissue hypoperfusion and increased Zn or other essential mineral requirements are of great importance in HbSS individuals with respect to body composition. These complications of SCD cause impairment of tissue which then affects almost all systems of the human body, causing retardation of growth and development.

That only body weight was significantly different when all measured anthropometric indicators of HbSS and HbSC were compared may be a reflection of the similarity in the molecular basis of two SCD genotypes, which is further supported by similar results of the correlation study. Moreover, it can be assumed that Zn, rather than anthropometry, better reflected the more severe nature of HbSS as the Zn level of homozygous SCD patients was significantly lower than that of heterozygous hemoglobinopathy-HbSC. Overall, our data derived from the measurement of anthropometry did not reinforce the notion that all markers of SCD can be used to justify that HbSS is the more severe genotype of the two. However, the results of body weight are in agreement with the past submissions in which laboratory investigation revealed significant differences in concentrations of lipid (total cholesterol, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol), creatinine, uric acid, and NO in HbSS compared with HbSC.^{[32],[33],[34],[35]}

Conclusion

The results of the study suggest that HbSS and HbSC which share some similarities from the genetic point of view (i.e., point mutation) display distinct and dissimilar levels of Zn but comparable anthropometry with the exception of body weight. Studies of this kind may help to identify different presentations that exist among the various genotypes of SCD with respect to its markers and initiate discussion that may have significant implications in widening our grasp of the pathophysiology of abnormal anthropometry of SCD. It is hoped that data obtained from the study will be helpful in keeping track of the clinical course of each genotype and further broaden our understanding concerning variations that exist in clinical presentations of the spectrum of genotypes of SCD.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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