key: cord-0843337-nnc9u2it
authors: di Filippo, Luigi; Formenti, Anna Maria; Giustina, Andrea
title: Hypocalcemia: the quest for the cause of a major biochemical feature of COVID-19
date: 2020-10-22
journal: Endocrine
DOI: 10.1007/s12020-020-02525-9
sha: e431e133aaa95917e4831d00068e456a47a9335d
doc_id: 843337
cord_uid: nnc9u2it

nan

However, it is likely that one single mechanism could not explain a so widespread phenomenon in a quite heterogenous population with different degree of severity and multifaced clinical background and manifestations [6] . In fact, besides the calcium dependent viral mechanism of action and the enhanced cellular permeability to calcium ions we previously hypothesized that hypovitaminosis D could be a predisposing factor to hypocalcemia [2] . Whereas we agree with the authors that chronic lack of vitamin D is not likely to be the only causative factor of acute hypocalcemia [7] , high prevalence of vitamin D deficiency in COVID-19 patients was reported by several studies [8] . Since vitamin D is involved in immunocompetence both with regard to innate and adaptive immunity [9] , it has been hypothesized that vitamin D deficiency may predispose to SARS-CoV-2 infection and lower levels of vitamin D could be related to increased COVID-19 severity [8] . Chronic vitamin D deficiency is known to alter calcium metabolism and infection by SARS-CoV-2 could predispose to/exacerbate hypocalcemia occurrence in COVID-19 patients, particularly in severe patients.

Interestingly, the authors of this letter also pointed out that early correction of hypocalcemia may be a therapeutic target to improve COVID-19 outcomes, and not just a predictor of severity [1] . We agree on this concept. In fact, to date, several clinical studies confirmed our initial findings that hypocalcemia may be a relevant risk factors for hospitalization [2] , but also for ICU admission and worse disease outcomes in COVID-19 patients [8] . Moreover, hypocalcemia per se when severe can complicate the cardiovascular and neurological picture of COVID-19 [2] . However, no data yet were published regarding the effect of calcium supplementation on COVID-19 hypocalcemic patients outcomes.

Therefore, currently it can only be suggested that calcium levels should always be checked at hospital admission, carefully monitored and replaced as clinically indicated in COVID-19 patients. Further studies are needed to clarify if calcium (and vitamin D) supplementation may have a relevant clinical impact in the natural history of COVID-19.

Conflict of interest The authors declare that they have no conflict of interest.

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