Vitamin D Deficiency and Low Serum Calcium as Predictors of Poor Prognosis in Patients with Severe COVID-19

Journal of the American College of Nutrition:

It is widely recognized that COVID-19 severity is a multifactorial condition; several risk factors have been identified, including advanced age, ethnicity, type 2 diabetes, hypertension, obesity, renal dysfunction, and cardiovascular diseases.

Interestingly, each of these factors is also known to be related to vitamin D deficiency in some way. This has led to raising the issue of whether inadequate vitamin D levels can affect the progression or even the prognosis of COVID-19.

In the ongoing pandemic, a substantial body of evidence, particularly from observational and ecological surveys, involving countries from all over the world, suggests an inverse relationship between Vitamin D status and the likelihood of infection, progression toward severity, and even fatality from COVID-19 (3,9). However, no definitive conclusions have yet been pronounced.

On the other side, Hypocalcemia is a common in-hospital complication, which occurs concurrently with other bio-clinical disorders such as an unbalanced status of vitamin D and parathyroid hormone (PTH) release, hypoproteinemia, and even chronic kidney disease. It is tightly linked to a poor prognosis, especially in critical patients; however, its association with the progression of COVID-19 has not been well investigated.

In light of the above-cited data, this study was carried out to assess both vitamin D and serum calcium status among COVID-19 severely affected patients, and to test the hypothesis of a possible link between their serum levels and short-term prognosis of this affection.

Among this study patients, hypocalcemia was very common and could be partly explained by impaired intestinal absorption, hypovitaminosis D, but mostly by hypoalbuminemia and hypoproteinemia; conditions that are particularly prevalent in intensive care, including severe cases of COVID-19.

This study demonstrates the high frequency of hypocalcemia and hypovitaminosis D in severe COVID-19 patients and provides further evidence of their potential link to poor short-term prognosis.

It is, therefore, possible that correction of albuminemia, hypocalcemia as well as supplementation with vitamin D may attenuate the severity and improve the vital prognosis.

Randomized controlled trials should be conducted to evaluate the effects of this supplementation and to confirm preliminary hypotheses drawn from observational studies.

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Abstract

Background: The severity of Coronavirus Disease 2019 (COVID-19) is a multifactorial condition. An increasing body of evidence argues for a direct implication of vitamin D deficiency, low serum calcium on poor outcomes in COVID-19 patients. This study was designed to investigate the relationship between these two factors and COVID-19 in-hospital mortality.

Materials: This is a prospective study, including 120 severe cases of COVID-19, admitted at the department of Reanimation-Anesthesia. Vitamin D was assessed by an immuno-fluoroassay method. Total serum calcium by a colorimetric method, then, corrected for serum albumin levels. The association with in-hospital mortality was assessed using the Kaplan-Meier survival curve, proportional Cox regression analyses and the receiver operating characteristic curve.

Results: Hypovitaminosis D and hypocalcemia were very common, occurring in 75% and 35.8% of patients. When analyzing survival, both were significantly associated with in-hospital mortality in a dose-effect manner. A cutoff value of 39 nmol/l for vitamin D and 2.05 mmol/l for corrected calcemia could predict poor prognosis with a sensitivity of 76% and 84%, and a specificity of 69% and 60% respectively.

Conclusion: This study demonstrates the high frequency of hypocalcemia and hypovitaminosis D in severe COVID-19 patients and provides further evidence of their potential link to poor short-term prognosis. It is, therefore, possible that the correction of hypocalcemia, as well as supplementation with vitamin D, may improve the vital prognosis.

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