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Issue: 2019, September, Volume 13, No 3
issue id: 2019_9_13_3
article id: 2019_9_13_3_13

Original Research

Prevalence of Vitamin D Deficiency in Healthy Adults

Prevalence of Vitamin D Deficiency in Healthy Adults


Sağlıklı Yetişkinlerde D Vitamini Eksikliği Prevalansı

Esra Paydaş Hataysal*1, Beyza Saraçlıgil2, Sedat Abuşoğlu1, Ali Ünlü1, Hüsamettin Vatansev1


Objectives: Vitamin D is a well-known hormone and important for many metabolic pathways and different health outcomes. The physiology of vitamin D is very complex. Multiple factors like ethnicity, age, sex, diseases, and medication influence vitamin D concentrations. In this study, our aim was to determine the prevalence of vitamin D deficiency among adults in  Turkey. Material-methods: The 25(OH) vitD3 test results of 2007 patients admitted to Selçuk University Medicine Faculty hospital between the years of 2015 and 2016 were analyzed, retrospectively. Patients using any vitamin D consisting drug, having chronic disease and inflammatory disorders were excluded. Vitamin D levels were measured by a chromatographic method (LC/MS/MS) with API3200 which is the gold standard to measure 25(OH)D3. Results: Our results show that the prevalence of vitamin D deficiency is about 67.9%  in our society. The mean value of vitamin D was 16,87 ng/mL and females had significantly lower 25(OH)D3 levels compared to males (p<0.001).The 25(OH)D3 levels were higher in summer and in fall than in winter and spring. (p<0.001) Conclusıons: The results indicate that vitamin D deficiency is prevalent in this study population despite high levels of sunshine and UV radiation throughout the year. Preventive treatments should be planned.


Key words: Vitamin D deficiency, LC/MS/MS, prevalence





Amaç: D vitamini, birçok metabolik yolakta rol alan ve bazı hastalıklarla ilişkili olan bir hormondur. Vitamin D fizyolojisi çok karmaşıktır.  Etnik köken, yaş, cinsiyet, hastalıklar ve ilaç kullanımı vitamin D konsantrasyonunu etkilemektedir. Bu çalışmada amacımız Türkiye’de sağlıklı erişkinlerde vitamin D eksikliği sıklığını belirlemekti. Yöntem: 2015-2016 yılları arasında Selçuk Üniversitesi Tıp Fakültesi Hastanesi'ne başvuran 2007 hastanın 25(OH)D3 test sonuçları retrospektif olarak incelendi. Vitamin D içeren ilaç kullanan, kronik hastalık veya enflamatuar hastalıkları olan hastalar çalışma dışı bırakılmıştır. D vitamini seviyeleri, 25(OH)D3 ölçmek için altın standart olan kromatografik yöntemle (LC / MS / MS) API3200 cihazı ile ölçülmüştür. Sonuçlar: Bulgularımız, çalışma popülasyonumuzda D vitamini eksikliği prevalansının yaklaşık %67,9 olduğunu göstermektedir. D vitamini ortalama değeri 16,87 ng/mL idi ve kadınlarda 25(OH)D3 seviyeleri, erkeklere göre anlamlı derecede düşüktü (p <0,001). Yaz ve sonbahar mevsiminde 25 (OH) D3 seviyeleri, kış ve ilkbahar mevsimine göre daha yüksekti.(p <0.001) Tartışma: Sonuçlarımız yıl boyunca yüksek düzeyde güneş ve UV ışığına rağmen, D vitamini eksikliğinin popülasyonumuzda yaygın olduğunu göstermektedir. Önleyici tedaviler planlanmalıdır.


Anahtar kelimeler: D vitamini eksikliği, LC/MS/MS, prevalans


Received Date / Geliş tarihi: 07.08.2018, Accepted Date / Kabul tarihi: 28.06.2019


1 Selçuk Üniversitesi, Tıp Fakültesi, Biyokimya Anabilim Dalı, Konya / TÜRKİYE.

2 Karatay Üniversitesi, Tıp Fakültesi, Biyokimya Anabilim Dalı, Konya / TÜRKİYE.

*Address for Correspondence / Yazışma Adresi: Esra Paydaş Hataysal, Selçuk Üniversitesi, Tıp Fakültesi, Biyokimya Anabilim Dalı, Konya / TÜRKİYE. E-mail: dr.esrapaydas@hotmail.com


Hataysal EP, Saraçlıgil B, Abuşoğlu S, Ünlü A, Vatansev H. Prevalence of Vitamin D Deficiency in Healthy Adults. TJFMPC, 2019; 13(3):335-341

DOI: 10.21763/tjfmpc.451729





In the last few years, more attention has been given to Vitamin D deficiency and several studies demonstrated that Vitamin D deficiency is prevalent worldwide. Moreover, there is a strong relationship between low circulating concentrations of vitamin D and many common diseases including skeletal and non-skeletal diseases. They can be preventable with Vitamin D supplementation in order to reduce disease activity.


Vitamin D plays a major role in human  biological functions, especially in the endocrine system. The pathway of vitamin D  synthesis consists of many metabolites such as  25-hydroxyvitamin D (25(OH)D), and 1,25-dihydroxy vitamin D (1,25(OH)D).  Synthesis of vitamin D3 is induced by UV light in skin and Cholecalciferol converted to 25-hydroxyvitamin D [25-(OH)D] or calcidiol by 25α-hydroxylase  in the liver and subsequently in the kidney into its’ active metabolite 1,25 dihydroxy vitamin D by the 1α-hydroxylase, an enzyme which is stimulated by parathyroid hormone. The synthesis of the metabolites is under control of 25-hydroxylase in the liver and 1-hydroxylase in the kidney. Thereafter, the active metabolite can enter cells and bind to either the vitamin D-receptor or  a responsive gene, such as that of calcium binding protein and help  calcium absorption.1 It has been estimated not more than 1% of the total solar UVB radiation reaches the earth’s surface and especially in winters it is difficult to produce Vitamin D.2-3  Clothing and glass absorbs all UVB radiation, so it prevents vitamin D production during sun exposure.2  Dietary intake of vitamin D is generally limited to oily fish and eggs.4 Multiple factors like  ethnicity, age, sex, clothing, season, time of the day,  diseases  and medication influence vitamin D concentrations. Blood concentration of 25(OH)D is the biomarker usually used by clinicians to determine vitamin D status.5


Vitamin D deficiency is a major public health problem worldwide in all age groups, even in those residing countries with low latitude, where it was generally assumed that UV radiation was adequate enough to prevent this deficiency and in industrialized countries, where vitamin D supplementation has been implemented for years.6  It has been estimated that approximately 30% and 60% of children and adults worldwide are vitamin D deficient and insufficient, respectively.7  There has been an association of vitamin D deficiency with  many diseases including  autoimmune disorders and  endocrinological diseases such as osteomalacia. In spite of the fact that the exact mechanisms by which vitamin D may reduce the risk for autoimmune diseases are not fully understood, it  was concluded  that vitamin D plays an important role in cellular immunity.8


Up until 1998, vitamin D deficiency was defined as a blood level of 25 hydroxyvitamin D[25(OH)D]; which represents a total concentration of both 25-hydroxyvitamin D2 and 25-hydroxyvitamin D3] of less than 10 ng/mL (25 nmol/L).3 This definition was mainly based on reports relating to blood levels of 25(OH)D and the development of rickets. 9 Recently, the following definitions are used to diagnose vitamin D status: for vitamin D deficiency   25(OH)D <20 ng/ml and for vitamin D insufficiency  25(OH)D ≥20 ng/ml and <30 ng/ml.10


The best method for determining a person’s vitamin D status is to measure serum  25(OH)D concentration because of its’ long half-life and easiness to measure. Most commercial assays are reliable enough to determine a person’s vitamin D  status.9 These include various radioimmunoassays and what is recently considered to be the gold standard: liquid chromatography-tandem mass spectrometry.11-12-13


The purpose of this study was to examine the prevalence of vitamin D deficiency in people without chronic disease or a significant risk factor and its correlates to test the hypothesis that vitamin D deficiency was common in Turkish population.





Study Population


This was a single-ethnicity study of 2007 healthy subjects aged 18-65years admitted to hospital for routine check-ups between January 2015 and December 2016. We measured serum 25(OH) D3  by a chromatographic method. The season of blood draw was classified as winter, spring, summer or fall. 


The data archive of the laboratory information system was searched for a 2-year period between 2015 January and 2016 December and among 6736 subjects searched for vitamin D3, 2007 remained (18–65 years old, 481 male and 1526 female) when we excluded the outliers for estimation of the prevalence of vitamin D deficiency.


Subjects were excluded if they had a significant cardiac, hepatic, oncologic disease, or disorders known to affect bone mineral metabolism including hyperthyroidism, hyperparathyroidism, osteomalacia or Paget’s disease. Pregnant women, patients with chronic renal failure or hospitalized patients were excluded from the study. Patients using any drugs containing vitamin D were also excluded. In the case of multiple test results for the same patient, only the first test result was included in the study. 4729 patients were excluded from the study because of having at least one of the above diseases and using Vitamin D containing drugs and 2007 patients remained.


Subjects were classified by sex and age. The season of blood draw was classified as winter (December through February), spring (March through May), summer (June through August)  or fall (September through November). 


We used the following definitions; vitamin D deficiency: 25(OH) D3<20 ng/ml; insufficient vitamin D status: 25(OH)D3  20–29 ng/ml  and optimal vitamin D status: 25(OH)D3  30–50 ng/ml .10-14-15-16  The prevalence of vitamin D deficiency is defined by four different thresholds of 25(OH)D3: ≤ 5,  ≤ 10, ≤20, and ≤30 ng/mL in this study.


Method of Study


The analytical method used for serum 25(OH)D3 was  Liquid chromatography-tandem mass spectrometry (LC-MS/MS)  performed by  liquid chromatography (Shimadzu LC-20AD system (Japan)) tandem mass spectrometry (Applied Biosystems MDS SCIEX(USA) API 3200). The quality of analyses in this laboratory was ascertained through the Vitamin D External Quality Assessment Scheme external controls. The inter-assay coefficients of variation were lower than 5%. The limit of detection was 4 ng/mL Liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods quantify vitamin D metabolites based on the compound-specific precursor to production mass-to-charge (m/z) transitions.17


Statistical Analysis


 Data analysis was performed using SPSS version 15(SPSS Inc, Chicago, IL, USA). Shapiro-Wilk analysis was used to test for gaussian or non-gaussian distribution. Our data were gaussian distributed variables. For gaussian distributed variables, data are expressed as arithmetic mean and ± standard deviation. Frequencies were presented as percentage (%). We assessed the significance of differences between two groups using independent samples t-test for gaussian-distributed data. P value ≤0.05 was considered statistically significant. The study was approved by Selçuk University Defense research ethics committee.



Using the definition of serum 25-OH-D3 concentrations 20 ng/mL. It was found that over 60% of Turkish adults, both men, and women, would be categorized as vitamin D deficient. Table.1 clearly shows that the prevalence of vitamin D deficiency is about 67.9% and vitamin D insufficiency prevalence is 20%. Only 12.1% of our study population has an adequate vitamin D level.














The aim of this study was to determine the prevalence of vitamin D deficiency specific to our region by using the archive of laboratory information system and find out whether deficiency of Vitamin D is similar to other populations.


The Institute of Medicine recently proposed that  25(OH)D3 level ≤20 ng/mL can be used to define vitamin D deficiency.18 Using this definition, vitamin D deficiency was highly prevalent in Konya, Turkey despite high levels of sunshine and UV radiation throughout the most seasons. The risk of Vitamin D deficiency was particularly high during winter and spring and among females.


The prevalence of vitamin D deficiency was found to be 72% in a study conducted by Durmuş et al. in Kayseri, another city of the Central Anatolia region.20 In addition, vitamin D deficiency was more frequent in women and there was no significant difference between age groups, similarly.


Hekimsoy et al. reported that Vitamin D deficiency was significantly more common among women (78.7%) than men (66.4%, p < 0.01). 25(OH)D levels were not significantly different in persons according to age as our study.21


Serum 25(OH) vitamin D levels vary depending on the seasons and reach its’ highest levels during summer months.22 Çidem et al. showed that the peak prevalence for vitamin D deficiency prevalence was in March during the year and the lowest level occurred in August in Turkey.19 Vitamin D deficiency was higher among females than among males. These findings support our study.


According to studies conducted in Turkey, vitamin D deficiency is common[19-22] . An  important reason why Vitamin D deficiency is  common in Turkey may be that people’s outdoor  activities are limited because of living urban areas in flats  and there is limited outdoor  social activities.19 Apartments  are more common than houses with gardens. In our era, because of our era’s working lifestyle, people must stay in closed areas for at least 8-10 hours in a day when there is sunshine. The use of sunscreen causes a reduction in the synthesis of vitamin D, while it protects the skin against the destructive effects of UVA and UVB20.  Furthermore, because of wearing sun protection during sun exposure and increased incidence of obesity vitamin D deficiency increases all over the World.9


It is reported that vitamin D deficiency is higher in individuals who dressed in a style which blocks sunlight and reported that vitamin D deficiency is three times higher in individuals who dressed in a style which blocks sunlight in Turkey.21 In a study conducted in Turkey, the serum vitamin D levels of women who prefer traditional clothing and covered clothes were shown to be at a lower level than in those whose clothing styles allowed exposure to sunlight.22


Regardless of latitude, lifestyle factors are crucial for vitamin D status and deficient. Insufficient vitamin D status and generally lower levels in females were observed in the Middle East with a strong relationship to the use of covering clothes 10 . According to the vitamin D test results of 60,979 people in the United Arab Emirates, Vitamin D deficiency was reported about 61.4% of women and 58.3% of males.23 In the study done in Iraq, another neighboring country of Turkey, the deficiency of vitamin D was around 50%. 24 In a study in Iran, the prevalence of vitamin D deficiency was about 50.8%.25  Surprisingly, Van der Wielen et al. reported that wintertime serum 25(OH)D3 concentrations of elder people from 11 European countries found 36% of men and 47% of women suffering from Vitamin D deficiency.26 In subjects over 65 years of age, vitamin D deficiency prevalence (<20 ng /ml) was found to be 44.7% in males and 56.1% in females in Holland.27


As a result of our study, it can be said that vitamin D deficiency is highly prevalent in Konya. Our results indicate that the risk of vitamin D deficiency and insufficiency was particularly high during winter and among females.


The characteristic features of our study are that our study population do not use vitamin D containing drug and they do not have any significant diseases. Furthermore, our measurement method is a gold standard to evaluate vitamin D levels. In addition, there are only a few studies conducted in the healthy patient group who don’t use Vitamin D containing drug in our country.


Limitations to our study need to be considered. The limitations were being a local study and our study includes female patients more than males.


In the literature, even in countries where is less sunshine, vitamin D levels are higher than us.  We think that environmental factors such as clothing and lifestyle play a role in vitamin D deficiency in Konya region at such high level. Since vitamin D deficiency is common in our society, most people use vitamin D supplements. In order to prevent vitamin D deficiency, it should be told by family physicians to patients how it is secreted in human body and people should be directed to social activities. Preventive measures should be taken more in order to prevent Vitamin D deficiency.





  1. Heaney RP, Dowell MS, Hale CA, Bendich A. Calcium absorption varies within the reference range for serum 25-hydroxyvitamin D. J Am Coll Nutr 2003;22:142-146.
  2. Wacker M, Holick MF. Sunlight and vitamin D: a global perspective for health. Dermato-Endocrinol. 2013;5(1):51–108.
  3. Holick MF. The vitamin D deficiency pandemic: Approaches for diagnosis, treatment and prevention. Rev Endocr Metab Disord (2017) 18:153–165 DOI 10.1007/s11154-017-9424-1
  4. Altieri B, Muscogiuri G, Barrea L, Mathieu C, Vallone CV, Mascitelli L et al. Rev Endocr Metab Disord. Does vitamin D play a role in autoimmune endocrine disorders? A proof of concept. (2017) Sep;18(3):335-346. doi: 10.1007/s11154-016-9405-9.
  5. Battault S, Whiting SJ, Peltier SL, Sadrin S, Gerber G, Maixent JM. Vitamin D metabolism, functions, and needs: from science to health claims. Eur J Nutr (2013) 52:429–441 DOI 10.1007/s00394-012-0430-5
  6. Palacios C, Gonzalez L. Is vitamin D deficiency a major global public health problem? J Steroid Biochem Mol Biol. 2014 October; 144PA: 138–145. doi:10.1016/j.jsbmb.2013.11.003
  7. Daly RM, Gagnon C, Lu ZX, et al. Prevalence of vitamin D deficiency and its determinants in Australian adults aged 25 years and older: a national, population-based study.  Clin Endocrinol. 2012; 77:26–35.
  8. Antico A, Tampoia M, Tozzoli R, Bizzaro N. Can supplementation with vitamin D reduce the risk or modify the course of autoimmune diseases? A systematic review of the literature. Autoimmun Rev 2012; 12:127-36; PMID:22776787; http://dx.doi.org/10.1016/j.autrev.2012.07.007
  9. Holick MF. Vitamin D deficiency. N Engl J Med 2007; 357:266–81.
  10. Granlund L, Ramnemark A, Andersson C  et al.  Prevalence of vitamin D deficiency and its association with nutrition, travelling and clothing habits in an immigrant population in Northern Sweden. European Journal of Clinical Nutrition (2016) 70, 373–37
  11. Holick MF, Siris ES, Binkley N, et al. Prevalence of vitamin D inadequacy among postmenopausal North American women receiving osteoporosis therapy. J Clin Endocrinol Metab 2005; 90:3215–24.
  12. Binkley N, Krueger D, Cowgill CS et al. Assay variation confounds the diagnosis of hypovitaminosis D: a call for standardization. J Clin Endocrinol Metab 2004; 89:3152–7.
  13. Holick MF, Chen TC. Vitamin D deficiency: a worldwide problem with health consequences- Am J Clin Nutr. 2008 Apr;87(4):1080S-6S
  14. Pearce SH, Cheetham TD. Diagnosis and management of vitamin D deficiency. BMJ 2010; 340: b5664.
  15. Rosen CJ, Gallagher JC. The 2011 IOM report on vitamin D and calcium requirements for North America: clinical implications for providers treating patients with low bone mineral density. J Clin Densitom 2011; 14: 79–84.
  16. Ross AC, Manson JE, Abrams SA, Aloia JF, Brannon PM, Clinton SK et al. The 2011 report on dietary reference intakes for calcium and vitamin D from the Institute of Medicine: what clinicians need to know. J Clin Endocrinol Metab 2011; 96: 53-58
  17. Tang JCY, Nicholls H, Piec I, Washbourne CJ, Dutton JJ.et all. Reference intervals for serum 24,25-dihydroxyvitamin D and the ratio with 25-hydroxyvitamin D established using a newly developed LC–MS/MS method, Journal of Nutritional Biochemistry 46 (2017) 21–29. 
  18. Institute of Medicine 2011 Dietary reference intakes for calcium and vitamin D. Washington, DC: The National Academies Press.
  19. Çidem M, Karacan İ, Beytemur O et al. Prevalence and risk factors for vitamin D deficiency in patients with widespread musculoskeletal pain. Turk J Med Sci (2017) 47: 728-731/ doi:10.3906/sag-1508-30
  20. Durmuş H, Çetinkaya F. Vitamin D Status of Adults in Kayseri, Turkey: Summer Time Population Based Cross-Sectional Study. J Clin Anal Med 2017;8(suppl 4): 325-9.
  21. Hekimsoy Z, Dinç G, Kafesçiler S, Onur E, Güvenç Y, Pala T et al. Vitamin D status among adults in the Aegean region of Turkey. BMC Public Health 2010;10(1):782
  22. Alagöl F, Shihadeh Y, Boztepe H, Tanakol R, Yarman S, Azizlerli H et al. Sunlight exposure and vitamin D deficiency in Turkish women. Journal of Endocrinological Investigation 2000;23(3):173-7
  23. Haq A, Svobodová J, Imran S, Stanford C, Razzaque MS. Vitamin D deficiency: A single centre analysis of patients from 136 countries. The Journal of steroid biochemistry and molecular biology 2016;164(9):209-13
  24. Al-Hilali K. Prevalence of Hypovitaminosis D in Adult Iraqi People Including Postmenopausal Women. Scientific Research Journal (SCIRJ), Volume IV, Issue IX, September 2016, ISSN 2201-2796.
  25. Hovsepian S, Amini M, Aminorroaya A,  Amini P,  Iraj B. Prevalence of Vitamin D Deficiency among Adult Population of Isfahan City, Iran. . J Health Popul Nutr (2011) Apr;29(2):149-155 ISSN 1606-0997.
  26. Van der Wielen RP, Löwik MR, van den Berg H, de Groot LC, Haller J, Moreiras O, van Staveren WA: Serum vitamin D concentrations among elderly people in Europe. Lancet 1995, 346:207-2l0.
  27. Lips P. Vitamin D status and nutrition in Europe and Asia. The Journal of Steroid Biochemistry and Molecular Biology 2007;103(3):620-5.

Table 1. Prevalence of vitamin D deficiency and insufficiency

Figure 1. Vitamin D levels according to months

Table 2. Vitamin D status according to gender

Table 3. Patients’ Vitamin D status according to season

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