Age, Sex and Seasonal Variations of Vitamin D Level in Children of Jammu Region
Rachna Sabharwal1, Pallavi Mahajan2
1 Assistant Professor, Department of Biochemistry, Government Medical College, Jammu, Jammu & Kashmir, India.
2 Demonstrator, Department of Biochemistry, Government Medical College, Jammu, Jammu & Kashmir, India.
NAME, ADDRESS, E-MAIL ID OF THE CORRESPONDING AUTHOR: Dr. Pallavi Mahajan, 154 A/D, Green Belt, Gandhi Nagar, Jammu-180004, Jammu & Kashmir, India.
E-mail: pallavi31mahajan@gmail.com
Introduction
Vitamin D deficiency is considered as one of the most common undiagnosed medical conditions in the world. Studies from India have reported prevalence of vitamin D deficiency varying from 30 to 100%. Among children, vitamin D deficiency can affect skeletal growth and development. A 25-hydroxyvitamin D (25(OH)D) provides single best assessment of vitamin D status as it has a half life of about 3 weeks, making it suitable indicator of vitamin D status.
Aim
This cross-divtional study was conducted to find out the prevalence of vitamin D deficiency in healthy children ≤ 15 years of age and their relation with seasonal variation.
Materials and Methods
Laboratory data of 25(OH)D was prospectively collected from apparently healthy children aged 7 days to 15 years in the Government Medical College, Jammu, India. Serum vitamin D was analysed by Chemiluminiscent microparticle immunoassay. Serum 25(OH)D level <5 ng/ml was considered severe vitamin D deficiency, 5-10 ng/ml as moderate and 10-20 ng/ml as mild hypovitaminosis. The data was analysed with the help of SPSS version 20.
Results
It was observed that out of total 150 children, prevalence of vitamin D deficiency (25-(OH)-D < 15 ng/ml) was present in 76 (50.67%) and insufficiency in 63 (42%) children. Ten children (6.67%) had severe vitamin D deficiency (< 5 ng/ml), 22 (14.67%) children had moderate hypovitaminosis (5-10 ng/ml) and 107 (71.33%) had mild (10-20 ng/ml). Only 11 (7.33%) children had normal levels of serum 25(OH)D (>20 ng/ml). The mean serum 25(OH)D concentrations were significantly lower from October to March (Winter) as compared from April to September(Summer) in children.
Conclusion
Vitamin D deficiency was observed among the younger age group. Thus adequate awareness among the masses should be done about the exposure of sunlight, dietary rich sources of vitamin D and fortification of foods with vitamin D for prevention and control of vitamin D deficiency.
Introduction
Serum 25-hydroxyvitamin D3, is the renowned marker of vitamin D status of the body. Vitamin D deficiency is a common disorder found in all age groups and in both genders [1]. Vitamin D deficiency is related with a large number of chronic diseases like type1 diabetes, hypertension, coronary heart diseases and multiple sclerosis as well as a number of inflammatory and non-inflammatory skeletal diseases. Vitamin D is a main factor responsible for the regulation of bone metabolism. Its role is not only confined to the skeletal system but extend to numerous skeletal organs like brain, heart, prostate, colon and immune cells [2]. The various health consequences of vitamin D deficiency include increased risk of fractures, loss of tooth, rickets and osteomalacia. The identification and treatment of vitamin D deficiency may be particularly important during childhood and adolescence as adequate vitamin D is necessary for skeletal health and bone mass growth [3]. There are various mechanisms that are related to 25-hydroxyvitamin D (25-(OH)-D) deficiency and disparity in lipid profile, but no consensus on the biological plausibility.
The factors which contribute to the production of vitamin D3 in the skin include the amount of pigment in the skin, duration of UV exposure, the season, place of residence, strength of the UV rays, age, intake of vitamin and physical activity [4].
Vitamin D insufficiency is defined as calcidiol (25-OH-D) concentrations <20 ng/mL in the paediatric population by both the American Academy of Paediatrics (AAP) and the Institute of Medicine (IOM). According to AAP 2008, the status of vitamin D is defined as severe deficiency < 5ng/ml, mild to moderate deficiency 5-15 ng/ml, insufficiency 16-20 ng/ml, and sufficiency 21-100 ng/ml [5] whereas, according to both the Endocrine Society and the National Kidney Foundation Kidney Disease Outcomes Quality Initiative (KDOQI) guidelines defines insufficiency as calcidiol concentrations <30 ng/mL. The KDOQI defines deficiency as < 15 ng/mL and Endocrine Society defines deficiency as < 20 ng/mL [6]. It was observed that infants need less sun exposure than adults to produce sufficient vitamin D levels as they have more surface area to volume ratio and better ability to generate vitamin D as compared to older people [7]. In a study conducted by Specker BL et al., it was observed that sun exposure to infants in diapers for 30 minutes maintained weekly Calcidiol concentrations of 11 ng/mL [8]. The AAP recommends that children less than six-month-old should be kept out in direct sunlight to decrease the risks of skin cancer [9]. In the paediatric population, still there are no recommendations present to corroborate the appropriate duration of sun exposure and the unevenness of synthesis of vitamin D in individuals would make such a recommendation difficult [10]. The deficiency of vitamin D does indeed constitute an epidemic in many populations across the world including the healthy populations. In India also, more than 90% of apparently healthy individuals have subnormal 25-(OH)-D levels. In the general population, low dietary intake of vitamin D and poor exposure to sunlight are common causes of vitamin D deficiency [11]. So by keeping these things in mind, the present study was conducted with the aim to estimate the levels of vitamin D in children in summer (April to September) and (October to March) winter seasons.
Materials and Methods
The present cross-sectional study was conducted in the Department of Biochemistry, Government Medical College, Jammu, in which the laboratory data of serum 25-(OH)-D was prospectively collected from 150 apparently healthy children, 7 days to 15 years of age coming for the first time to Paediatric OPD of Government Medical College, SMGS Hospital, Jammu for minor ailments including upper respiratory tract infections, fever, diarrhea and children coming to OPD for immunization.
The study was carried out from October 2016 to September 2017. Children with mild, severe or life threatening systemic diseases were not included in the study. Other exclusion criteria were children with a history of chronic illnesses, autoimmune diseases or recurrent fractures, children undergoing diagnostic biopsies, bronchoscopy or endoscopy and children on medication known to affect serum 25-(OH)-D. The study was approved by the institutional ethics committee.
Personal and demographic data of children were collected. Serum 25-(OH)-D was analysed in serum by Abbott Architect autoanalyser by chemiluminiscent microparticle immunoassay [12]. In the present study, children with serum 25-(OH)-D level < 5 ng/ml was considered severe vitamin D deficiency, 5 to 10 ng/ml as moderate hypovitaminosis and 10 to 20 ng/ml as mild hypovitaminosis. According to AAP 2008, the status of vitamin D is defined as severe deficiency < 5ng/ml, mild to moderate deficiency 5-15 ng/ml, insufficiency 16-20 ng/ml, and sufficiency 21-100 ng/ml.
The statistical analysis was conducted using SPSS version 20. Descriptive statistics were used to present the clinical characteristics of the participants. Continuous variables were described using the means and standard deviation. All p-values were two sided and p<0.05 was considered to be statistically significant.
Results
A total of 150 children, 7 days to 15 years of age were enrolled in the study. Serum 25-(OH)-D concentrations were available for all the subjects, of whom 95 (63.33%) were females and 55 (36.67%) were males. The mean age±standard deviation of the study group was 8.11±4.60 years, while mean±standard deviation serum 25-(OH)-D concentration was 14.17±5.13 ng/ml (range 0.1 to 25 ng/ml). Prevalence of vitamin D deficiency (25-(OH)-D < 15 ng/ml) was present in 76 (50.67%) and insufficiency in 63 (42%) children. Ten children (6.67%) had severe vitamin D deficiency (< 5 ng/ml), 22 (14.67%) children had moderate hypovitaminosis (5-10 ng/ml) and 107 (71.33%) had mild (10-20 ng/ml). Only 11 (7.33%) children had normal levels of serum 25-(OH)-D (>20 ng/ml) [Table/Fig-1].
Distribution of children according to serum 25(OH)D concentration.
| Serum 25(OH)D concentration (ng/ml) |
|---|
| Deficiency | Insufficiency | Normal |
|---|
| <15 ng/mlNumber of children (Percentage of children) | 16-20 ng/mlNumber of children (Percentage of children) | ≥20 ng/mlNumber of children (Percentage of children) |
| 76 (50.67%) | 63 (42%) | 11 (7.33%) |
Age wise and sex wise distribution of children according to serum concentration levels are given in [Table/Fig-2,3]. Out of 76 children with vitamin D deficiency, 40.79% were in the age group of 6 to 10 years, while 64.47% were females.
Age wise distribution of children according to serum 25(OH)D concentration.
| Age group (in years) | Serum 25(OH)D concentration (ng/ml) |
|---|
| <5Number of children (Percentage of children) | 5-10Number of children (Percentage of children) | 10-20Number of children (Percentage of children) | ≥20Number of children (Percentage of children) |
|---|
| 0-5 | 1 (10%) | 9 (40.91%) | 29 (27.10%) | 6 (54.55%) |
| 6-10 | 6 (60%) | 7 (31.82%) | 35 (32.71%) | 3 (27.27%) |
| 11-15 | 3 (30%) | 6 (27.27%) | 43 (40.19%) | 2 (18.18%) |
| Total | 10 | 22 | 107 | 11 |
Sex wise distribution of children according to serum 25(OH)D concentration.
| Sex | Serum 25(OH)D concentration (ng/dl) |
|---|
| <5No. of children (%) | 5-10No. of children (%) | 10-20No. of children (%) | ≥20No. of children (%) |
|---|
| Male | 1 (10%) | 10 (45.45%) | 40 (37.38%) | 4 (36.36%) |
| Female | 9 (90%) | 12 (54.55%) | 67 (62.62%) | 7 (63.64%) |
| Total | 10 | 22 | 107 | 11 |
Comparison of mean serum 25-(OH)-D levels of children with respect to gender and seasonal variation is given in [Table/Fig-4]. Mean serum 25-(OH)-D concentration was higher in male children (14.58 ng/ml) as compared to female children (13.94 ng/ml), though the difference between the two was statistically not significant. However, mean serum 25-(OH)-D level from October to March (11.27 ng/ml) was significantly lower as compared from April to September (15.62 ng/ml).
Comparison of mean serum 25(OH)D concentration levels of children with respect to gender and seasonal variation.
| Variables | Serum 25 (OH)DConcentration (ng/ml)Mean±standard deviation | Statistical inference(unpaired t-test) |
|---|
| Gender: |
| Male (n=55) | 14.58±4.72 | t= 0.73; p=0.46* |
| Female (n=95) | 13.94±5.36 |
| Seasonal variations: |
| October to March (n=50) | 11.27±5.42 | t=5.32; p < 0.0001** |
| April to September (n=100) | 15.62±4.32 |
* p-value is more than 0.05, not significant
** p-value is less than 0.05, highly significant
Discussion
It has been observed that out of 150 children, prevalence of vitamin D deficiency (25-(OH)-D < 15 ng/ml) was present in 76 (50.67%) and insufficiency in 63 (42%) children. Only 11 (7.33%) children had normal levels of serum 25 hydroxyvitamin D (>20 ng/ml). Mean serum 25-(OH)-D level from October to March was significantly lower as compared from April to September. There were wide variations in serum 25-(OH)-D across the various seasons in all decades of age. Similar results were observed in other studies [13]. Gordon CM et al., found that during the winter, serum 25-(OH)-D concentrations were significantly lower than the values obtained during summer season [14].
The geography of the region and its latitude affects the amount and quality of solar radiation particularly the intensity of UVB radiation reaching surface of the earth. In regions with high latitude, the intensity of UVB is not sufficient to synthesize adequate amount of vitamin D in the autumn or winter. Also, in the winter season, decrease in the duration of outdoor sunlight exposure and wearing more clothes may affect serum 25-(OH)-D levels. Even with more daily intake of vitamin D, seasonal variations in geographic regions at higher latitudes result in greater vitamin D deficiency [15]. The synthesis of vitamin D depends on number of factors like exposure to UV light, duration of exposure, skin pigmentation, use of sun blocks, climate, and regional variation. Skin pigmentation is one of the limitations associated with lower synthesis of vitamin D by black skins during the summer months [16]. Insufficient daily intake of vitamin D on daily basis can lead to its deficiency in the summer and autumn despite sufficient exposure to sunlight [17].
In our study, it was observed that vitamin D deficiency was present among all the age groups. In another study, it was reported that the prevalence of vitamin D deficiency in 1212 children, aged between 4 and 15 years was 58.6% [18]. It was also observed in our study that the females have decreased vitamin D levels as compared to males [Table/Fig-3]. In a study conducted by Saeidlou et al, the prevalence of vitamin D deficiency was 27.9% in females and 6.9% in males [1]. This can be due to the fact that women especially living in high latitude have less body surface exposure due to clothing [2].
Vitamin D deficiency is prevalent in India, a finding that is unexpected in a tropical country with abundant sunshine [19]. India is located between 8.4°N and 37.6°N latitude with majority of its population living in regions experiencing optimum sunlight throughout the year. Despite its sunny environment, hypovitaminosis is common in India [20].
Limitation
The results of this study have several limitations in regard to the duration of exposure, physical activity. Even though the responsible variables involved in changes in vitamin D status is reported in this study, may also engross general population but these observations cannot be generalized but can be applied only to children attending medical clinics.
Conclusion
In conclusion, this study showed that serum levels of vitamin D can be different in the two seasons regardless of gender variations in children. The serum vitamin D levels are lowest in the winter and highest in the summer months. So while estimating the vitamin D levels, seasonal variation should also be taken into account.
* p-value is more than 0.05, not significant** p-value is less than 0.05, highly significant
[1]. Saeidlou SN, Vahabzadeh D, Babaei F, Vahabzadeh Z, Seasonal variations of vitamin D and its relation to lipid profile in Iranian children and adults Journal of Health, Population and Nutrition 2017 36:2110.1186/s41043-017-0096-y28532484 [Google Scholar] [CrossRef] [PubMed]
[2]. Heidari B, Haji MB, Mirghassemi Seasonal variations in serum vitamin D according to age and sex Caspian J Intern Med 2012 3(4):535-40. [Google Scholar]
[3]. Christy B, Turer Hua Lin, Glenn Flores, Prevalence of vitamin D deficiency among overweight and obese US children Paediatrics 2013 131:e15210.1542/peds.2012-171123266927 [Google Scholar] [CrossRef] [PubMed]
[4]. Costanzo PR, Elías NO, Kleiman Rubinsztein J, García Basavilbaso NX, Piacentini R, Salerni HH, Ultraviolet radiation impact on seasonal variations of serum 25-hydroxy-vitamin D in healthy young adults in Buenos Aires Medicina (B Aires) 2011 71(4):336-42.[In Spanish] [Google Scholar]
[5]. Misra M, Pacaud D, Petryk A, Collett-Solberg PF, Kappy M, Vitamin D deficiency in children and its management: review of current knowledge and recommendations Paediatrics 2008 122(2):398-17.10.1542/peds.2007-189418676559 [Google Scholar] [CrossRef] [PubMed]
[6]. National Kidney Foundation, Inc. Guideline Prevention and treatment of vitaminD insufficiency and vitamin D deficiencyin CKD patients. KDOQI clinical practice guidelines for bone metabolism and diseasein children with chronic kidney disease.2005. http://www.kidney.org/professionals/kdoqi/guidelines_pedbone/guide8.htm. Accessed December 28, 2017 [Google Scholar]
[7]. Munns C, Zacharin MR, Rodda CP, Batch JA, Morley R, Cranswick NE, Prevention and treatment of infant and childhood vitamin D deficiency in Australia and New Zealand: a consensus statement Med J Aust 2006 185(5):268-72.10.5694/j.1326-5377.2006.tb00558.x16948623 [Google Scholar] [CrossRef] [PubMed]
[8]. Specker BL, Valanis B, Hertzberg V, Edwards N, Tsang RC, Sunshine exposure and serum 25-hydroxyvitaminD concentrations in exclusivelybreast-fed infants J Paediatr 1985 107(3):372-76.10.1016/S0022-3476(85)80509-6 [Google Scholar] [CrossRef]
[9]. American Academy of Paediatrics, Committee on Environmental Health Ultraviolet light: a hazard to children 1999 104(2 pt 1):328-33.10.1542/peds.104.2.328 [Google Scholar] [CrossRef]
[10]. Lee JY, So TY, Thackrey A review on vitamin D deficiency treatment in Paediatric population J Paediatr Pharmacol Ther 2013 18(4):277-91.10.5863/1551-6776-18.4.27724719588 [Google Scholar] [CrossRef] [PubMed]
[11]. Shah P, Kulkarni S, Narayani S, Sureka D, Supriya Dutta S, Vipat AS, Prevalence study of vitamin d deficiency and to evaluate the efficacy of vitamin D3 granules 60,000 IU supplementation in vitamin d deficient apparently healthy adults Indian Journal of Clinical Practice 2013 23(12):827-32. [Google Scholar]
[12]. National Committee for Clinical Laboratory Standards. Procedures for the handling and processing of blood specimens; approved guideline- third edition. NCCLS Document H18-A3; Wayne (PA); NCCLS; 2004 [Google Scholar]
[13]. Sahu M, Bhatia V, Aggarwal A, Rawat V, Saxena P, Pandey A, Vitamn D deficiencyin rural girls and pregnant women despite abundant sunshine in northern India Clin Endocrinol (Oxf) 2009 70(5):680-84.10.1111/j.1365-2265.2008.03360.x18673464 [Google Scholar] [CrossRef] [PubMed]
[14]. Gordon CM, DePeter KC, Feldman HA, Grace E, Emans J, Prevalence of vitamin D deficiency among adolescents Arch Paediatr Adolesc Med 2004 158:531-37.10.1001/archpedi.158.6.53115184215 [Google Scholar] [CrossRef] [PubMed]
[15]. Hughes AM, Lucas RM, Ponsonby AL, Chapman C, Coulthard A, Dear K, The role of latitude, ultraviolet radiation exposure and vitamin D in childhood asthma and hayfever: an Australian multicenter study Paediatr Allergy Immunol 2011 22:327-33.10.1111/j.1399-3038.2010.01099.x20880353 [Google Scholar] [CrossRef] [PubMed]
[16]. Farrar MD, Kift R, Felton SJ, Berry JL, Durkin MT, Allan D, Recommended summer sunlight exposure amounts fail to produce sufficient vitamin D status in UK adults of South Asian origin Am J Clin Nutr 2011 94:1219-24.10.3945/ajcn.111.01997621918215 [Google Scholar] [CrossRef] [PubMed]
[17]. Burgaz A, Akesson A, Michaelsson K, Wolk A, 25-hydroxyvitamin D accumulation during summer in elderly women at latitude 60 degrees N J Intern Med 2009 266:476-83.10.1111/j.1365-2796.2009.02125.x19570054 [Google Scholar] [CrossRef] [PubMed]
[18]. Chung IH, Kim HJ, Chung S, Yoo EG, Vitamin D deficiency in Korean children: prevalence, risk factors, and the relationship with parathyroid hormone levels Ann Paediatr Endocrinol Metab 2014 19:86-90.10.6065/apem.2014.19.2.8625077091 [Google Scholar] [CrossRef] [PubMed]
[19]. Sachan A, Gupta R, Das V, Agarwal A, Awasthi PK, Bhatia V, High prevalence of vitamin D deficiency among pregnant women and their newborns in northern India Am J Clin Nutr 2005 81(5):1060-64.10.1093/ajcn/81.5.106015883429 [Google Scholar] [CrossRef] [PubMed]
[20]. Mehlawat U, Singh P, Pande S, Current status of vitamin D deficiency in India Innov Pharmaceu Pharmaco 2014 2(2):328-35. [Google Scholar]