Study of Serum Vitamin D Level in Different Socio-Demographic Population - A Pilot Study

Background: Recently, we see in our clinical practice that many patients who are coming with generalized body aches and pains and diagnosed as fibromyalgia or chronic fatigue, not adequately responding to treatment. When their vitamin D level was done, it was found to be low and correction of their low vitamin D level improved their symptoms dramatically. Despite abundant sunshine in Bangladesh, allowing vitamin D synthesis all the year round, why our people are developing hypovitaminosis D inspired us to do this current study. Our present study is designed to estimate the prevalence of vitamin D deficiency among adult patients presented with aches & pains as well as to study the association of low vitamin D levels with different socio-demographic parameters. Methods: A cross sectional observational study was conducted among 212 adult patients aged 18 years and above presented with generalized body aches and pains, attended both outpatient and inpatient departments of Popular Medical College Hospital during the period of March’16- August’16 ( 6 months). Association between vitamin D status & the individual specific variables was statistically analyzed. Results: The prevalence of vitamin D deficiency among the study population was found to be100% in all age groups. Among 212 study population, 73.6% were female (n=156) & 26.4% were male (n=56). Mean Vitamin D level among male was 14.29 (SD 4.68) & among female was 12.64 (SD 4.74). The factors associated with severely deficient Vitamin D level were female sex, urban population, o 19 (1) : 22-29


Introduction:
Vitamin D has received considerable interest from the medical community and the public at large because of recent evidence for the non-skeletal effects of vitamin D combined with the finding of widespread global deficiency.Vitamin D deficiency is more common than previously thought.It has been estimated that almost 1 billion people in the world suffer from vitamin D deficiency or insufficiency. 1 Vitamin D has been appreciated for its role in calcium homeostasis and bone health since its identification in 1921. 2 While scientists know for decades that vitamin D deficiency leads to bone diseases like rickets & osteomalacia, recently they have found connections between low vitamin D levels and a wide range of other illnesses, such as diabetes, different type of cancers, autoimmune diseases, psychological disorders like depression, cardiovascular diseases, hypertension, lumbago, pre-eclampsia. 3,4tamin D is a fat soluble steroid prohormone mainly produced photochemically in the skin from 7 dehydrocholesterol.Vitamin D consists of 2 bioequivalent forms.Vitamin D 2 (D 2 ), also known as ergocalciferol, is obtained from dietary vegetable sources and oral supplements.Vitamin D3 (D3), also known as cholecalciferol, is obtained primarily from skin exposure to ultraviolet B (UVB) radiation in sunlight, ingestion of food sources such as oily fish and variably fortified foods (milk, juices, margarines, yogurts, cereals, and soy), and oral supplements.Aside from rich sources such as oily fish, the

Study of Serum Vitamin D Level in Different Socio-Demographic Population -A Pilot Study
HOMAYRA TAHSEEN HOSSAIN, 1 QUAZI TARIKUL ISLAM, 2 MD.ABUL KASHEM KHANDAKER, 3  There is a critical requirement of vitamin D for bone and mineral homeostasis, and in particular in preventing rickets and osteomalacia.In addition, the vitamin D receptor (VDR) located within the keratinocytes makes these cells a unique photoendocrine vitamin D system that is stimulated by UVB irradiation.2Binding of vitamin D on keratinocyte VDR enhances the production of cathelicidins, which have potent microbicidal activities and are a major component of the innate immune system.8This argues for an important role of vitamin D in immune defense.Indeed, most tissues and cells in the body express VDRs.Besides its immune-modulatory and anti-inflammatory properties, there is now increasing epidemiological and experimental evidence for a protective effect of vitamin D not only on the risk of fall and fracture but also on dental health, colorectal cancer, hypertension, and cardiovascular mortality.9Thus, reaching and maintaining an optimal vitamin D status at all life stages is of major individual and public health importance.
However, the blood levels of 25(OH)D that define vitamin D deficiency remain somewhat controversial.
Currently, most agree that vitamin D concentration below 20 ng/ml indicates vitamin D deficiency, whereas a concentration of 21-29 ng/ml is considered insufficient, and a 25(OH)D level of 30-100 ng/ml defines vitamin D sufficiency.10 Recently, we are observing in our clinical practice that many patients who were coming with generalized body aches and pains and diagnosed as fibromyalgia or chronic fatigue, not adequately responding to treatment.When their vitamin D level was done, it was found to be low and correction of their low vitamin D level improved their symptoms dramatically.Despite abundant sunshine in Bangladesh, allowing vitamin D synthesis all the year round, why our people are developing hypovitaminosis D striked our mind and inspired us to do this current study.Update data regarding Bangladeshi population are limited.Our present study is designed to estimate the prevalence of vitamin D deficiency among adult patients presented with aches & pains as well as to study the association of low vitamin D levels with different socio-demographic parameters.The measurement of vitamin D status will provide the opportunity for preventive & therapeutic interventions.
A number of factors such as duration and time of sun exposure, latitude, season, atmospheric pollution, clothing style, use of sun blocks, skin pigmentation as well as obesity and the presence of several chronic diseases influence the photosynthesis and bioavailability of Vitamin D and contribute to the risk of impaired Vitamin D status of the body.2,11Public health-awareness campaigns, as well as food fortification with vitamin D are efficacious and affordable means to prevent vitamin D deficiency.

Methods: Study subjects:
A cross sectional observational study was conducted among the adult patients aged 18 years and above presented with generalized body aches and pains, attended both outpatient and inpatient department of Popular Medical College Hospital during the period of March'16-August'16 ( 6 months).Total 212 adult patients, both male and female were recruited in the study who gave consent after explanation.Following subjects were excluded from the study-I.
Age <18 years.IV.Individuals who suffer from chronic diseases that affect the absorption of Vitamin D such as chronic liver disease & kidney disease.
V. Subjects who are taking drugs that could influence vitamin D like steroid and anti-epileptics.
The study was approved by the Institutional Ethics Committee.There is no conflict of interest.

Data Collection:
After taking consent from the individuals fulfilling inclusion criteria of the study, a predesigned structured questionnaire was administered and filled by the doctor attending the patient.The questionnaire recorded socio-demographic characters, clothing style, sunlight exposure, dietary habits, smoking habits, patient's awareness about importance of sun exposure, BMI & presence of important co-morbidity like diabetes & hypertension.
Data of total household income were used as indicator of socio-economic status.Average monthly income was reported in 3 categories: Lower class < 20,000 Taka/ month, middle class 20,000-50,000 Taka/month & higher class > 50,000 Taka/month.
Height of the patient was measured to the nearest 0.1cm.Weight was measured in light clothing.Body Mass Index (BMI) was calculated as body weight in Kg divided by squared body height in meters.BMI was then classified as underweight (<18.5 kg/m 2 ), normal weight (18.5-24.9kg/m 2 ), overweight (25-29.9kg/m 2 ) and obesity (≥30kg/m 2 ) according to the categories of World Health Organization. 12tamin D analysis: The serum 25 In our study, hypovitaminosis D was found in all age groups.Highest percentage of severely deficient vitamin D level (<10 ng/ml) was found in 31-50 years of age (37.5%).8][19] Even if regularly exposed to sunlight, elderly people produce 75% less cutaneous D3 than young adults. 20Our active working age group are suffering from severely low vitamin D level possibly due to lifestyle factors is a striking finding of our study.
In our current study, we found that the people belonging to the lower socio-economic status & living in rural areas are having higher level of vitamin D -more exposure to sunlight is the contributing factor.About 94% of our study population was having brown to dark skin complexion.This skin tone with high melanin pigment (natural sunscreen) produces significant lesser amount of vitamin D. 21 In our study, we found an inverse association between Vitamin D level & BMI.3][24] With data from the US 'National Health and Nutrition Examination Survey' (NHANES) Forrest et  al. 2011 demonstrated that the risk of having serum 25(OH)D levels <50 nmol/l was about 2 times higher in obese than non-obese persons. 25Daly et al. 2012 described that in obese men and women adjusted serum 25(OH)D levels were 8.3-9.5 nmol/l lower than in persons with normal weight. 26The reasons for the observed lower levels of serum 25 (OH)D among person with higher BMI are still unclear.There are some evidences that vitamin D is accumulated in adipose tissue with decreased bioavailability and lower serum levels in persons with higher BMI. 27sociation of 25OHD with glucose regulation and type 2 diabetes has been shown in several studies 28 including studies done in Finland. 2925OHD level has been associated Study of Serum Vitamin D Level in Different Socio-Demographic Population-A Pilot Study with insulin sensitivity indices, 30 and low 25OHD has been shown to predict later development of type 2 diabetes. 31n our study, 21.5% of the study population was having diabetes mellitus.One of the most striking finding from our study is the unawareness of the importance of sun exposure among two-third of our study population (64.2%).If this issue is not addressed properly by public health awareness programme, the huge burden of hypovitaminosis D cannot be combatted.
We recognize some limitations of our study.It was a pilot study with a small sample size of 212.As it was a private Medical College Hospital (mainly outpatient department) based study, sample might not be representative of the total population of our country.Blood samples were collected only once during the month of March-July.It would be useful if study subjects were evaluated at different times of the year to study the seasonal variation.Food intake data were collected by a food frequency questionnaire which does not permit precise estimates of nutrient intake.

Conclusions:
Despite abundant sunlight in Bangladesh, the prevalence of vitamin D deficiency among adult patients presenting with generalized aches and pains is found to be 100% across all age groups & both sexes.Female gender, urbanization, obesity, dark skin complexion, wearing skin covering veils, lifestyle factors (staying inside home/ office/ car-lack of sunlight exposure) -are some of the important factors associated with hypovitaminosis D in Bangladesh.
From the findings of our study, we strongly recommend to screen for vitamin D deficiency who are at risk based on diet, sun exposure, obesity indices, age, sex & lifestyle factors, as features of hypovitaminosis D are mostly reversible with proper replacement.We also recommend public health efforts in Bangladesh should address the need for vitamin D sufficiency within their population.Increasing awareness about the importance of sun exposure and encouraging the consumption of natural food sources rich in vitamin D, like egg will be helpful.Vitamin D fortification or supplementation may also be viable options to improve the vitamin D status of our population.

Conflict of interest:
This study was funded by Bangladesh Society of Medicine (BSM).
HAM NAZMUL AHASAN 2 vitamin D content of most foods is between 50 and 200 IU per serving.This value varies greatly by region of the world because fortification markedly improves the availability of vitamin D through diet.Only an estimated 10-20 % of vitamin D is supplied through nutritional intake.5Both D2 and D3 are biologically inert.Once absorbed from the intestine, they are metabolized in the liver to 25-hydroxyvitamin D [25(OH)D], composed of 25(OH)D2 and 25(OH)D3; 25(OH)D (also called calcidiol) is subsequently converted to 1,25-dihydroxyvitamin D [1,25(OH)2D], also known as calcitriol, in the kidney and select other tissues by the action of the 1α-hydroxylase enzyme.The predominant effects of vitamin D are exerted through the endocrine and autocrine actions of calcitriol via activation of the vitamin D receptor in cells.6The serum levels of 25(OH)D are measured to determine vitamin D status.Serum 25(OH)D is considered the best functional indicator of vitamin D status reflecting the sum of cutaneous synthesis and oral intake.7 who were not willing to participate in the study.III.Patients who were taking vitamin D, Calcium with vitamin D or Multivitamins as supplement.
13H)D is the most reliable marker of vitamin D status.So, we measured serum 25 (OH) D levels of all study participants & recorded the result in our data collection sheet.Biochemical estimations were carried out using the Architect 25-OH Vitamin D assay which is a quantitative delayed one-step competitive immunoassay.It is used to determine the presence of vitamin D in human serum and plasma using CMIA technology with flexible assay protocols, referred to as Chemiflex.13Statisticalanalysis was carried out using SPSS 22. Descriptive statistics was carried out.Frequencies are presented for categorical variables.Continuous variables were presented as mean ± SD.Mean different test (Z-test) was done to find out the association of Vitamin D levels with different socio-demographic factors.A p value <0.05 was considered to be statistically significant.Mean vitamin D level among male was 14.29 & female was 12.64.So, though both the values are low, mean vitamin D level of males are higher than that of females.Lack of sun exposure due to staying inside home (61.7% housewives) and wearing skin covering veils (64.7% of our female study group wearing veils) are contributing to this low vitamin D levels in females than males.

Table - I
Socio-demographic characteristics of the subjectsStudy of Serum Vitamin D Level in Different Socio-Demographic Population-A Pilot Study