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Year : 2019  |  Volume : 22  |  Issue : 4  |  Page : 573-577

Investigation of Vitamin D levels in medical staff in a dental clinic

1 Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Kayseri, Turkey
2 Genome and Stem Cell Research Center, Erciyes University, Kayseri, Turkey
3 Private Dental Clinic, Faculty of Medicine, Kayseri, Turkey
4 Department of Endocrinology and Metabolism, Faculty of Medicine, Kayseri, Turkey

Date of Acceptance29-Jan-2019
Date of Web Publication11-Apr-2019

Correspondence Address:
Dr. F Dogruel
Department of Oral and Maxillofacial Surgery, Erciyes University, Kayseri - 38039
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/njcp.njcp_523_18

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Aims: Recently, Vitamin D deficiency is pandemic now. The main reason of vitamin D deficiency is inadequate exposure to sunlight. Vitamin D level in nutrients is low and it can be ineffective to meet the daily requirements. Vitamin D is synthesized in the skin by ultraviolent radiation. In the present study, the authors aimed to investigate serum 25(OH) D levels of the medical staff working in different positions in the Faculty of Dentistry. Subjects and Methods: A total of 51 dentists, 28 dental assistants, 11 secretaries, and 10 nurses working in the Faculty of Dentistry, Erciyes University between November and December 2014 were included to the study. The serum 25(OH) D levels of the participants were evaluated. Results: Of the participants, 62 were females and 38 were males with a mean age of 30.17 ± 5.77 (range: 20–49) years. The mean vitamin D levels were found to be 12.1 ± 8.37 ng/mL (range: 2.1–38.3). A total of 51 participants had severe vitamin D insufficiency, while three participants had normal vitamin D levels with only one dentist. Conclusion: According to the results of present study, dental staff should be considered as a high-risk group for vitamin D deficiency. Vitamin D deficiency and insufficiency is a common problem among medical staffs as in several working groups such as white-collar workers and bankers. Results of present study suggest that insufficient exposure to the sunlight may lead to severe vitamin D deficiency in dental professionals. Vitamin D supplementation may be recommended to the dental staff.

Keywords: Dental professionals, healthcare providers, vitamin D, vitamin D deficiency

How to cite this article:
Dogruel F, Gonen Z B, Canpolat D G, Ocak H, Bayram F. Investigation of Vitamin D levels in medical staff in a dental clinic. Niger J Clin Pract 2019;22:573-7

How to cite this URL:
Dogruel F, Gonen Z B, Canpolat D G, Ocak H, Bayram F. Investigation of Vitamin D levels in medical staff in a dental clinic. Niger J Clin Pract [serial online] 2019 [cited 2021 May 17];22:573-7. Available from:

   Introduction Top

Vitamin D is a fat-soluble vitamin which has important effects on calcium balance and bone metabolism and it affects almost all cells in the body.[1] In addition, it has beneficial effects on several systems and diseases, such as immune modulation, prevention of development of autoimmune diseases, chronic conditions, and cancer.[2]

Vitamin D is mainly synthesized in the skin by sunlight and it is the only hormone which is synthesized in the skin by exposure to the sunlight.[3] Ultraviolent B (UVB) which is present in the sunlight initiates vitamin D synthesis in skin, UVB causes conversion of provitamin D (7-dehydrocholesterol) to previtamin D3 and, then, to vitamin D3. Vitamin D3, which is synthesized in the skin, is initially hydroxylated in liver and serum 25-hydroxyvitamin D [25(OH) D] levels are produced. Then, it undergoes re-hydroxylation in kidneys and 1,25(OH) D, the active form of vitamin D, is produced. Active vitamin D has direct effects on intestinal calcium absorption, mineralization process in bone, and contraction activity in muscle tissue.[4],[5]

Although vitamin D deficiency has been associated with only musculoskeletal disorders (i.e. rickets, osteomalacia), recent studies have demonstrated that vitamin D is important life-long for growth, development, and protection of a healthy body.[6] Several types of cancer,[7] coronary artery disease,[8],[9] and type 1-2 diabetes,[8],[10],[11] which are associated with vitamin D deficiency have been extensively investigated. Microbial diseases,[12] multiple sclerosis, rheumatoid arthritis, hypertension, and Alzheimer disease have been associated with vitamin D deficiency.[13],[14],[15] Furthermore, it has been demonstrated that mental health is also adversely affected by vitamin D deficiency.[16],[17],[18],[19]

Currently, pandemic vitamin D deficiency is present. The main reason of vitamin D deficiency is insufficient exposure to the sunlight. Vitamin D deficiency is a commonly seen condition in all races, in all geographical regions, and socioeconomic conditions. Except vitamin D-enriched nutrients, vitamin D level in nutrients is low and it can be insufficient to meet the daily requirements. Direct skin exposure to sunlight is necessary for synthesis. As the appropriate angle of beam is between 10.00 A.M. and 03.00 P.M., vitamin D can be synthesized, if the sunlight exposure is between these hours.[16] Living near polar regions, reduced exposure to the sunlight, dark skin, aging, sun protection cream, obesity, increased vitamin D metabolism (i.e., hyperparathyroidism, lymphoma), malabsorption, nephrotic syndrome, chronic renal failure, chronic hepatic failure, and drugs (i.e., anticonvulsants, antituberculosis drugs) are main causes of vitamin D deficiency. Therefore, in addition to dietary habits in the society, the daily environment and working conditions have been also become important.

The medical staffs are at the highest risk, as they spend most of the day, particularly the hours of sunlight exposure, in large concrete buildings and close environments with insufficient light. In the literature, vitamin D deficiency is high among the medical staffs.[20],[21],[22] Thus, in the present study, it was aimed to investigate the serum 25(OH)D levels in the dental staffs working in different positions in a university dental hospital.

   Subjects and Methods Top

The study was approved by the Ethics Committee of Erciyes University and was conducted in accordance with the principles of the Declaration of Helsinki. A written informed consent was obtained from each participant before the study.

A total of 100 individuals including dentists, dental assistant, secretaries, and nurses working in Faculty of Dentistry, Erciyes University, Kayseri, Turkey between November 2014 and February 2015 were included to the study. Those who had chronic disease and drug use, which could affect vitamin D metabolism, and who received vitamin D supplement within the past 3 months were excluded from the study. In all patients, fasting serum 25(OH) D levels were measured using the high-performance liquid chromatography (HPLC) method. The vitamin D levels of the participants were evaluated. Serum's total calcium and phosphate levels were assayed by automated analysis using colorimetric and enzymatic methods. Serum intact parathyroid (PTH) concentrations were measured by an electrochemiluminescence immunoassay in Cobas e 601 (Roche Diagnostics, Mannheim, Germany) with the inter- and intraassay coefficient of variation of 1.1–2.0 and 2.8–3.4%, respectively. Serum 25 (OH)-D was measured by HPLC method with Chromsystems in HPLC Agilent 1100 series (Germany). In addition, serum calcium, phosphorus, and PTH levels were measured in all participants. The daily duration of mean sunlight exposure of the participants was recorded.

According to serum 25(OH) D levels, vitamin D level >30 ng/mL was accepted as normal, vitamin D level of 20–30 ng/mL was accepted as vitamin D insufficiency, <20 ng/mL was accepted as vitamin D deficiency, and <10 ng/mL was accepted as severe vitamin D deficiency.[16]

Statistical analysis

Statistical analysis was performed using the SPSS for Windows version 16.0 software (SPSS Inc., Chicago, IL, USA). Descriptive data were expressed in mean ± standard deviation (SD). A P value of < 0.05 was considered statistically significant.

   Results Top

Of a total of 100 individuals, 62 were females and 38 were males with a mean age of 30.17 ± 5.77 (range: 20–49) years. Vitamin D levels were found not statistically different between individuals <30 years of age (n: 54) and >30 years of age (n: 46) (P = 0.4). A total of 51 of the participants were dentists, 28 were dental assistants, 11 were secretaries, and 10 were nurses. All the participants worked from 08.00 am to 17.00 pm and the study group was homogenous in term of mean exposure time to the sunlight. Demographical characteristics of the participants and vitamin D levels are shown in [Table 1].
Table 1: Demographical characteristics of the participants

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The mean vitamin D levels among the dental staff was 12.05 ± 7.42 ng/mL (range: 2.1–38.3), the mean level of PTH 36.3 ± 15.9 (range 11.6–94.4), Ca 9.38 ± 0.3 mg/dL (range 8.1–10.2), andP3.22 ± 0.5 (range 1.9–5.5) mg/dL. The levels of PTH, Ca, andPare shown in [Table 2].
Table 2: Ca, P, and PTH levels according to vitamin D levels

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The mean level of vitamin D was found as 13.5 ± 8.1 ng/mL (range: 3.4–38.3) in males and 11.1 ± 6.8 ng/mL (range: 2.1–28.9) in females. No statistically significant difference in the vitamin D levels was found between the male and female participants (P = 0.12).

While severe vitamin D deficiency was found in 51 participants (6.53 ± 2.03), vitamin D deficiency was found in 36 participants (14.48 ± 2.5), and vitamin D insufficiency was found in 10 participants (24.55 ± 3.31). Only three participants (35.03 ± 3.77) had normal vitamin D levels and only 1 dentist (35.9) had the normal range of vitamin D [Figure 1]. There was no statistically significant correlation between vitamin D and PTH P = 0.171 [Figure 2]. There was no significant difference between the sunlight exposure time of the participants. All of the participants exposed to the sunlight less than 2 hours in a day.
Figure 1: Distribution graph of the vitamin D in each occupation.

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Figure 2: The correlation graph between the levels of serum 25OHD and plasma PTH.

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   Discussion Top

In the present study, it was aimed to investigate the serum 25(OH)D levels of the dental staffs at the first time in the literature. Considering the working conditions, the medical staff are at the highest risk for vitamin D deficiency.[20],[21],[22] Recent studies have demonstrated that vitamin D may have a role in the protection of immune system and bone health.[4] Vitamin D deficiency decreases intestinal calcium absorption and, to a less extent, phosphate absorption, thereby, leading to secondary parathyroidism. Although insufficient vitamin D intake contributes to the development of vitamin D deficiency, one of the main reason is insufficient exposure to the sunlight. According to geographical latitude of Turkey, vitamin D is mostly synthesized between May and November. The participants reported that they worked in closed environments due to busy schedule and their exposure to sunlight was less than 2 hours in a day and they only exposed sunlight during the annual leave.

In the present study, the mean vitamin D level was found 12.05 ± 7.4 ng/mL (range: 2.10–38.3). In the study of Yıldız et al.,[21] the mean vitamin D level was 12.5 ± 0.6 ng/mL among 96 medical staff. In the study of Erden et al.,[23] the mean vitamin D level was 8.98 ± 4.89 ng/mL among medical staff working in anesthesia department. In another study, Rajebi et al.[24] found vitamin D level to be 11.7 ± 9.3 ng/mL in 114 nurses. Medical staffs are not exposed to sufficient UVB light due to long working hours and they do not take sufficient vitamin D replacement; therefore, the majority of the staff are at high risk for vitamin D deficiency.[21] In a prospective study, which was performed in fellows of the Department of Internal Medicine in the United States, low 25(OH)D levels (<20 ng/mL) were found in 74% of the participants at the end of winter and in 26% of the participants at the end of summer.[25] In another cross-sectional study which was performed in fellows in Brazil, 25(OH) D level was found to be <20 ng/mL in 57.4% of the participants.[22]

The main function of vitamin D is to preserve calcium/phosphorus balance of the organism together with PTH by intestinal calcium and phosphorus absorption. The efficacy of vitamin D is not limited only with maintenance of bone health by regulation of calcium homeostasis, it has also proapoptotic, anti-inflammatory, and immunomodulatory roles and it increases insulin production and decreases renin synthesis.[26] There is an inverse relationship between 25(OH)D levels and PTH levels. As vitamin D level decreases, parathyroid glands response by increasing PTH synthesis and secretion.[26] In the study of Oǧuz et al.,[20] in which they investigated the predictive role of calcium, phosphorus, and PTH in predicting 25(OH)D deficiency, the mean PTH values were found to be significantly higher in the vitamin D deficiency group, compared to the other groups. However, the authors concluded that PTH alone was not sufficient to demonstrate vitamin D deficiency and, even when all parameters were evaluated; it was insufficient to have a predictive role.

In the literature, there are few studies evaluating vitamin D levels among medical staff in different countries. In a study which was performed in 340 physicians and nurses in Qatar, vitamin D level was found to be below 30 ng/mL in 97% of the participants.[27] In another study in healthy population in India, one of the subgroups was determined as physicians and nurses and vitamin D level was found to be low in this group.[28] In another study which was performed among the hospital staff in India, vitamin D level was found to be low in 66% of the participants.[29] In addition, vitamin D levels at the end of winter and at the end of summer were measured in medical staff including medical students in Boston, and it was found that 32% of the young adult population had vitamin D deficiency at the end of winter.[30] The mean level of 25(OH)D was found to be quite low in these studies in both patients and healthy individuals, and the results of the present study are similar to these previous findings.

Vitamin D deficiency has been gradually increasing all over the world. In previous studies, reduced UVB and sunlight exposure have been associated with an increased prevalence of vitamin D deficiency.[27],[28],[29],[30],[31] In addition, serum 25(OH)D level shows seasonal variation: it reaches the peak level in the summer months.[32],[33] In countries which are present at and above 37°North latitude, the angle of sunlight during November–February is oblique, and most of them are absorbed in ozone layer of the atmosphere. As less UVB light reaches the earth surface in winter, the tendency for vitamin D deficiency is high in people living at and above 37°North latitude.[4],[34] The latitude of Iran is at 36°00′ North. It has been reported that there is no significant seasonal variation in serum vitamin D levels.[35] However, it has been reported that vitamin D deficiency is frequent during winter–spring period in Denmark, which is located at 56°00′ North latitude.[32] Turkey is located at 39°57′ North latitude between Iran and Denmark. In present study, severe vitamin D deficiency was found in 51 participants, vitamin D deficiency was found in 36 participants and vitamin D insufficiency was found in 10 participants. Only three participants had normal vitamin D levels and only one dentist had the normal range of vitamin D. Therefore, dental staff should be considered high-risk group for vitamin D deficiency.

In conclusion, vitamin D deficiency and insufficiency is a common problem among dental staffs according to results of present study. It has been understood that vitamin D insufficiency has increased to the highest degree all over the world among medical staffs, white-collar workers, and bankers. Limited exposure to the sunlight might cause severe vitamin D deficiency in healthy individuals. Dental staffs are also at risk for several chronic diseases in the long term due to constantly low vitamin D levels. This patient group may admit to orthopedics or physical therapy policlinics mainly complain from musculoskeletal system diseases and diffuse body aches and this situation leads to both workforce and time consumption. Therefore, based on the results of present study, vitamin D supplementation is recommended to the dental staffs to prevent aforementioned problems.


The study did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

It was presented as a poster in Turkish Congress of Endocrine and Metabolism Disorders May 2015, Turkey.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

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  [Figure 1], [Figure 2]

  [Table 1], [Table 2]


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