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Low Circulating Vitamin D in Intensive Care Unit-Admitted COVID-19 Patients as a Predictor of Negative Outcomes.

Take Home Message

The main findings of this single-center retrospective observational study conducted in Russia were that ICU patients (n = 40) with COVID-19 had deficient serum 25(OH)D concentrations on admission and that a serum 25(OH)D concentration ≤9.9 ng/mL (£24.75 nmol/l) at admission was predictive of in-hospital mortality.


  • All 40 patients had low serum 25(OH)D concentrations at admission [median = 12 ng/ml (30 nmol/l); ranging 9–15 ng/mL (22.5-37.5 nmol/l)].
  • In total, 18 patients (45%) did not survive; 22 patients (55%) survived to Day 60.
  • The median serum 25(OH)D concentration was greater in survivors [13.3 ng/mL (33.25 nmol/l); ranging 10.0–17.1 ng/mL (25-42.75 nmol/l)] than in non-survivors [9.6 ng/mL (24 nmol/l); ranging 7.9–14.2 ng/mL (19.75-35.5 nmol/l)].
  • Kaplan–Meier survival curves for the 25(OH)D concentrations on admission to the ICU showed that the 60-d mortality rate was greater in those with serum 25(OH)D concentrations ≤9.9 ng/mL (£75 nmol/l) (n = 14, 71%) than in those with concentrations >9.9 ng/mL (>24.75 nmol/l) (n = 26, 31%).
  • Patients with serum 25(OH)D concentrations ≤9.9 ng/mL (£75 nmol/l) had a 5.6-fold higher risk of death than those with concentrations >9.9 ng/mL (>24.75 nmol/l) (OR: 5.63; 95% CI: 1.35, 23.45).
  • The durations of stay in the ICU [9 d (ranging 2–22 d) compared with 13 d (ranging 5–17 d)] and hospital stay [16 d (ranging 11–25 d) compared with 14 d (ranging 8–19d)] did not significantly differ between the ≤9.9 ng/mL and >9.9 ng/mL serum 25(OH)D concentration groups.


Forty adult patients (20 men, 50%; 20 women, 50%) with confirmed COVID-19 in Moscow, Russia who were admitted to the intensive care unit (ICU), had a serum 25(OH)D concentration measurement on the day of admission and had a definite outcome (death or discharge) were included in this study.

Things to Keep in Mind

This study has several limitations:

  • The observational design of the study cannot substantiate causality between serum vitamin D levels and severity of COVID-19 disease. The effect of adding vitamin D to the therapy of COVID-19 patients remains to be established.
  • The study enrolled a very limited number of patients (N = 40) at a single center. This study included patients from a single center in Russia and may not be generalizable to all COVID-19 patient populations.
  • Comorbidities were not adjusted for but have been shown in other studies to alter COVID-19 patient outcomes.
  • The low serum 25(OH)D concentrations may have been influenced by seasonality, because the study was performed in April after a long period of limited sun exposure.

Author’s Conclusions

In conclusion, we found that the ICU patients had a low serum 25(OH)D concentration on admission. Serum 25(OH)D concentrations ≤ 9.9 ng/mL on admission can be used to predict in-hospital mortality in patients with COVID-19 infection. An intervention study is warranted to elucidate the usefulness of vitamin D supplementation for the treatment and/or prevention of COVID-19.

Study Design

  • This is a single-center retrospective observational study of patients admitted between April 6 and April 27, 2020 to the Federal Scientific and Clinical Center of Specialized Types of Medical Care and Medical Technologies of the Federal Medical and Biological Agency of Russia in Moscow, Russia.
  • The primary endpoint was mortality at day 60.
  • The serum 25(OH)D concentrations were assessed by chemiluminescence immunoassay. Vitamin D status was categorized using cutoffs based on serum 25(OH)D concentrations: <10.0 ng/mL (25 nmol/l) represented severe deficiency, 10.0–19.9 ng/mL (25 nmol/l-49.75 nmol/l) represented a deficiency, 20.0–29.9 ng/mL (50-74.75 nmol/l) represented insufficiency, and ≥30.0 ng/mL (75 nmol/l) represented sufficient 25(OH)D concentrations.
  • The Mann–Whitney test, Fisher’s exact test, Kaplan–Meier analysis, and receiver operator characteristic (ROC) analysis were used to assess serum 25(OH)D concentration as a predictor of COVID-19 mortality.


Bychinin MV, Klypa TV, Mandel IA, Andreichenko SA, Baklaushev VP, Yusubalieva GM, Kolyshkina NA, Troitsky AV. Low Circulating Vitamin D in Intensive Care Unit-Admitted COVID-19 Patients as a Predictor of Negative Outcomes. J Nutr. 2021 May 12:nxab107. doi: 10.1093/jn/nxab107. Epub ahead of print. PMID: 33982128; PMCID: PMC8194597.

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