Vitamin D is a preprohormone known to play a key role in the metabolism of phosphates and calcium. Its main source is the synthesis by ultraviolet (UV) radiation in the skin [
Ecuador is located on the equator at a latitude of −0.95, with two seasons: winter (January–April) and summer (May–December). The solar radiation index is 10-11 UV, which is considered as very high radiation levels; however, the general population takes measures to avoid sun exposure which results in insufficient levels of vitamin D. The objective of this study was to determine vitamin D status by measuring serum calcidiol (25 (OH)-D) in an Ecuadorian population that had attended a first consultation at a Rheumatology Center.
Retrospective study of Ecuadorian subjects from the city of Guayaquil, Ecuador, who had an initial study of serum 25 (OH)-D, as the indicator of vitamin D status, from 2015 to 2016.
The 25 (OH)-D serum levels of the patients had been measured in the same laboratory. Samples were analyzed by the chemiluminescence method with an Advia Centaur® assay system. Serum 25 (OH)-D levels are not standardized for each population; however, the following (1.4–6) are considered: Ideal: 30–40 ng/dL Deficiency: 30–20 ng/dL Insufficiency: 20–10 ng/dL Severe insufficiency: <10 ng/dL.
The patients were from the city of Guayaquil located in Guayas province, at six meters above sea level and at a latitude of −0.95, with a solar exposure index of 10-11 UV.
The data was analyzed using the statistical program SPSS v 22, with
269 Ecuadorian subjects were analyzed, with a mean age of 54.73 ± 16.58; 85%
Demographic data and 25 (OH)-D levels.
|
% |
|
|
---|---|---|---|
Demographic data | |||
Women | 228 | 85 | — |
Men | 41 | 15 | — |
Mean age | 54.73 ± 16.58 |
|
|
25 (OH)-D | |||
Normal | 81 | 30 |
|
Deficiency | 141 | 53 |
|
Insufficiency | 44 | 16 |
|
Severe insufficiency | 3 | 1 |
|
|
|||
Mean | 27.29 ± 10.12 | ||
Women | 27.01 ± 9.72 | ||
Men | 28.89 ± 12.18 |
25 (OH)-D levels, as indicator of vitamin D status, in Ecuadorian subjects.
Men had higher levels of 25 (OH)-D than women, but levels in both sexes were deficient with a mean of 27.01 ± 9.72 and 28.89 ± 12.18, respectively.
Higher levels of 25 (OH)-D were observed in the summer months in relation to the winter months, with February being the month with the highest 25 (OH)-D level 34.26 ± 12.7 (Figure
25 (OH)-D levels during the 12 months of the year. Months with the lowest sun exposure: January–April (winter); months with the highest sun exposure: May–December (summer).
Patients were divided into age groups according to the WHO scale [
Age groups.
Age group |
|
% |
|
---|---|---|---|
Children, adolescents < 18 years old | 4 | 1.5 | 0.001 |
Young adults 18–35 years old | 44 | 16.4 | 0.001 |
Adults 36–64 years old | 133 | 49.4 |
|
Elderly > 65 years old | 88 | 32.7 | 0.001 |
Mean 25 (OH)-D levels in the age groups.
This is a descriptive study of an Ecuadorian population in which levels of 25 (OH)-D, as an indicator of vitamin D status, were determined. 70% of the population showed levels below 30 ng/dl, considered insufficient.
The origin of the population is an important factor when evaluating vitamin D status, because Ecuador is located on the equator at a latitude of −0.95, where the radiation and intensity of UV rays are greater. You would expect the population to have sufficient levels of vitamin D; however, Ecuadorians take measures to avoid sun exposure.
Common sunscreens absorb solar radiation. It has been shown that a sunscreen with a protection factor (SPF) of 30 can absorb up to 95–98% of UV radiation, which reduces the production of vitamin D3 in 95–98% [
A study conducted in Atahualpa, a village located on the Ecuadorian coast, determined 25 (OH)-D levels in 220 subjects, of which 25% had levels below 20 ng/ml and was directly related to ischemic events and diffuse subcortical brain damage [
Climatic seasons have a significant influence on the production of cutaneous vitamin D [
A study by dermatologists in Australia showed that approximately 87% of Australians after summer had vitamin D levels below 20 ng/dL [
Reports from Mexico, Europe, Asia, India, and Africa show that more than 50% of the world’s population is at risk of hypovitaminosis D [
As for the age group, vitamin D levels have been shown to be inversely related to age [
Studies have demonstrated the utility of vitamin D in cardiovascular diseases [
The advantages of our study were that the subjects admitted to the study were not institutionalized, the technique used for the determination of vitamin D was universal, and the origin of the population was exclusively the city of Guayaquil. Within the limitations we consider the lack of sun exposure data and specific measures of sun protection. However, the stated objectives were reached, thus determining that 70% of the population studied showed deficient levels of 25 (OH)-D. More studies of vitamin D status determination are needed in other cities of Ecuador with different geographic characteristics such as the Andes and Amazon region.
It is evident that despite the location of Ecuador and the intensity of UV rays it receives throughout the year, Ecuadorian subjects have insufficient levels of vitamin D. In the summer months vitamin D levels are higher compared to winter months. Also, vitamin D levels are higher in the elderly compared to other age groups.
The authors declare no conflicts of interest.