Discussion
Our study evaluated the vitamin D deficiency prevalence and the
association between vitamin D deficiency and clinical and inflammatory
markers in our patients hospitalized for COVID-19 infection. To the best
of our knowledge, we have not found any study on vitamin D levels in
pediatric patients diagnosed with COVID-19 in our literature review of
resources in English. We aim to investigate whether children diagnosed
with COVID-19 had vitamin D deficiency as well as the realationship
between vitamin D deficiency and clinical outcomes.
Although there are no adequate studies on vitamin D levels and its
effects in children with COVID-19, there are several studies evaluated
the relationship between other respiratory pathogens and vitamin D. In
some clinical studies, vitamin D has been shown to protect children from
lung infection. Children with vitamin D deficiency or insufficiency are
more susceptible to respiratory infection (13). A meta-analysis and
systematic review of 25 randomized controlled trials by Martineau et al.
showed that vitamin D generally protects against acute respiratory
infection (14). In an important study covering 1582 people by Li et al.
with aim of determining the relationship between 25(OH)D in children and
pulmonary infection, the community-acquired pneumonia group displayed a
lower value than the control group, and there were also significant
differences between the pneumonia group and pneumonia-derived sepsis
group ( p <0.001), and there was association between
lower serum 25(OH)D level and more serious symptoms (15).
Daneshkhah et al. observed that high CRP was inversely correlated with
25(OH)D, and they thought vitamin D to have a possible role in reduction
of complications caused by abnormal inflammation and cytokine storm
given the CRP as a marker for cytokine storm and considering its
association with vitamin D deficiency (16). Some previous studies found
negative correlation between 25(OH) D vitamin level and pneumonia
severity, CRP level, increased risk of sepsis, ARDS risk and increased
production of proinflammatory cytokines such as IL-6 (17-21). In the
present study, a negative correlation was found between vitamin D level
and fever symptom (p = 0.023), but there was no significant finding in
terms of CRP level and clinical severity.
In a study conducted by Alipio M et al. observed that vitamin D level
was low or insufficient in 74.1% of patients diagnosed with COVID 19
and also found a statistically significant difference between serum
25(OH)D level and clinical outcomes (p <0.001) (22). In
another study of Lau et al. regarding the relationship between vitamin D
deficiency and the severity of COVID-19 disease in adult age group, low
levels of vitamin D were found in 75% of the cases and 84.6% of the
patients in intensive care unit (23). In a study conducted on adults,
Raharusa et al. found deficient or insufficient levels of vitamin D in
47.3% of 780 patients diagnosed with COVID-19. Vitamin D was
insufficient in 27.3% of them and deficient in 20% of them. They
observed mortality in 49.1% of vitamin D insufficient cases, 46.7% of
deficient ones and 4.1% of normal ones, and found statistically
significant results between vitamin D level and mortality (p
<0.001). However, the comorbid factors concomitant with the
majority of those with deficient and insufficient vitamin D levels in
their studies make it difficult to evaluate the relationship between
mortality and vitamin D alone (24). In our study, 72.5% of our cases
were vitamin D deficient or insufficient, and 2 patients (100%) in need
of treatment in the intensive care unit had the vitamin D level of below
10 ng/ml, and had comorbid diseases, but none of them had mortality. In
our study, the distribution of disease severity according to vitamin D
levels was not found significantly different (p = 0.097). Yet, although
the virulence mechanisms related to COVID-19 are not fully
characterized, the fact that clinical severity and mortality rate of the
disease generally progress better in children compared to adults
suggests that it may be due to Ace 2 receptor count and cytokine storm
being less than that of adults depending on immunological response. When
COVID 19 diagnosed childrens who had deficient and insufficient level of
vitamin D (group 1) and covid 19 diagnosed childrens who had normal
level of vitamin (group 2) compared at admission, Group 1 had
significantly higher fever symptom (34.5%, 10) than Group 2 (0%) (p =
0.038). A negative correlation was found between vitamin D level and
fever symptom (p = 0.023), but there was no significant finding in terms
of CRP level and clinical severity.
A study conducted by Ilie et al., found that average vitamin D levels in
each country and the COVID-19 cases were negatively correlated with the
number of deaths caused by COVID-19 (25). Since there were no patients
in our study who died, there was no evaluation of the relationship
between vitamin D levels and mortality.
In conclusion, our study is the first to evaluate vitamin D levels and
its relationship with clinical findings in pediatric patients diagnosed
with COVID-19. There are significantly lower levels of vitamin D in
children with COVID-19 than those in the control group. This shows that
vitamin D, which is effective in the immunological mechanism, also has
an effect in the physiopathology of the disease. Vitamin D levels are
associated with fever. Since we did not have any patients lost, their
relationship with mortality could not be evaluated. More studies are
needed in children for evaluation of the association between vitamin D
with clinical and laboratory findings of the disease and its effect on
mortality.