Researchers studied 179 older adults hospitalized with COVID-19 to see if the amount of calcium in their blood could predict who might not survive. They found that patients with higher levels of a specific type of calcium (ionized calcium) had a higher risk of dying within three months of getting COVID-19. This discovery suggests that doctors might be able to use simple blood tests to identify which older COVID-19 patients need extra care and attention. While this is interesting, more research is needed to understand why this connection exists and how doctors should use this information.

The Quick Take

  • What they studied: Whether the amount of a specific type of calcium in the blood could help predict which older adults hospitalized with COVID-19 might not survive three months after infection
  • Who participated: 179 older adults (geriatric patients) who were admitted to a hospital in France with COVID-19 during two time periods in 2020-2021
  • Key finding: Older adults with higher ionized calcium levels (above 1.22 mmol/L) were about 2.4 times more likely to die within three months compared to those with lower levels
  • What it means for you: If you’re an older adult with COVID-19, doctors might use a simple blood test to check your calcium levels as one tool to understand your risk. However, this is just one piece of information—many other factors affect survival, and this finding needs more research before it changes how doctors treat patients.

The Research Details

This was a retrospective cohort study, which means researchers looked back at medical records of patients who had already been treated. They examined 179 older adults who were hospitalized with COVID-19 at a specific hospital unit in France during two separate time periods (March-June 2020 and October 2020-March 2021). The researchers measured ionized calcium levels in blood samples taken when patients arrived at the hospital and then tracked whether patients survived or died over the next three months.

The researchers also collected information about many other health factors that might affect survival, including age, sex, nutrition status, kidney function, inflammation markers, vitamin D use, and how sick patients were when admitted. This allowed them to see if calcium levels predicted survival even after accounting for these other important factors.

The study used statistical methods called Cox regression models to analyze the data. This technique helps researchers understand whether calcium levels independently predict survival or if other health factors are really responsible for the differences in outcomes.

This research approach is important because it uses real-world patient data rather than laboratory experiments. By looking at actual patients and their outcomes, researchers can discover patterns that might help doctors identify high-risk patients earlier. The fact that researchers controlled for many other health factors makes the findings more reliable—it suggests the calcium connection isn’t just because sicker patients happen to have different calcium levels.

This study has some strengths: it included a reasonable number of patients (179), measured calcium levels objectively through blood tests, and accounted for many other health factors. However, there are limitations to consider: the sample size is moderate, the study only looked at patients from one hospital in France, and it’s observational rather than experimental. The study shows an association between calcium and survival but cannot prove that high calcium causes death—other unknown factors could explain the connection.

What the Results Show

The main finding was that older adults with ionized calcium levels above 1.22 mmol/L had significantly higher mortality rates at three months compared to those with lower levels. Specifically, patients with higher calcium were 2.4 times more likely to die. This association remained strong even after researchers adjusted for other important health factors like age, kidney function, nutrition status, and inflammation markers.

The researchers used survival curves to visualize this difference—essentially creating a graph showing how many patients in each group survived over the three-month period. The group with higher calcium levels showed a noticeably steeper decline, meaning more patients in that group died sooner.

The statistical analysis showed this finding was unlikely to be due to chance (p = 0.003), which means there’s strong evidence for a real association. However, it’s important to note that this doesn’t mean high calcium causes death—it means these two things occur together in a way that’s unlikely to be random.

The study examined several other health factors in relation to survival, including parathyroid hormone levels, inflammation markers (C-Reactive Protein), nutrition status (albumin levels), kidney function, and vitamin D supplementation. While the abstract doesn’t detail all secondary findings, the researchers controlled for these factors in their analysis, suggesting they all played a role in patient outcomes. The fact that the calcium association remained significant even after accounting for these factors suggests it provides additional information beyond what these other markers tell us.

This research adds to growing evidence that mineral and electrolyte balance is important in severe COVID-19. Previous studies have shown that various blood chemistry abnormalities predict poor outcomes in COVID-19 patients. This study specifically highlights ionized calcium—the form of calcium that’s biologically active in the body—as a potential marker. The finding fits with what we know about how severe infections affect the body’s ability to regulate minerals and electrolytes, though the specific mechanism for calcium in COVID-19 isn’t yet fully understood.

Several important limitations should be considered: First, this study only included patients from one hospital in France, so results might not apply to other populations or healthcare settings. Second, the study is observational, meaning researchers watched what happened rather than randomly assigning patients to different treatments—this makes it harder to prove cause and effect. Third, the study looked back at existing medical records, which means some information might be incomplete or measured differently than in a planned research study. Fourth, while 179 patients is a reasonable sample, larger studies would provide stronger evidence. Finally, the study doesn’t explain why high calcium levels are associated with worse outcomes—understanding the mechanism would help doctors know how to respond to this finding.

The Bottom Line

Based on this research, ionized calcium levels may be a useful additional tool for doctors to assess risk in older adults hospitalized with COVID-19 (moderate confidence level). However, this should not be used as the only predictor of outcomes—many other factors matter. Doctors should continue using established risk assessment methods while considering adding calcium level checks to their evaluation. More research is needed before this becomes a standard part of COVID-19 care.

This finding is most relevant to: (1) doctors and hospitals treating older adults with COVID-19, who might use calcium testing as one additional risk assessment tool; (2) older adults hospitalized with COVID-19 and their families, who might discuss calcium levels with their medical team; (3) researchers studying COVID-19 and mineral metabolism. This finding should NOT be used by people to self-diagnose or self-treat at home, as calcium levels require professional medical interpretation.

If this finding were to be implemented in clinical practice, doctors would measure calcium levels at hospital admission (immediate) and use this information to guide treatment decisions throughout the hospital stay. The three-month timeline in this study reflects when researchers measured survival outcomes, not how quickly patients might see benefits from any intervention based on calcium levels.

Want to Apply This Research?

  • For older adults recovering from COVID-19, track weekly blood work results if available (specifically ionized calcium levels if measured), along with overall health status and any symptoms. Record the date, calcium level if known, and general wellness rating on a 1-10 scale.
  • If you’re an older adult who had COVID-19, discuss calcium and mineral status with your doctor during follow-up appointments. Ask whether your calcium levels were checked during hospitalization and what they mean for your recovery. Ensure adequate calcium intake through diet (dairy, leafy greens, fortified foods) or supplements as recommended by your healthcare provider.
  • Work with your healthcare provider to establish a follow-up schedule that includes periodic blood work for the first three months after COVID-19 hospitalization. If calcium levels are measured, track trends over time rather than focusing on single measurements. Share results with your doctor and discuss any concerning patterns.

This research describes an association between calcium levels and outcomes in older adults hospitalized with COVID-19, but does not prove that calcium causes these outcomes. This information is for educational purposes and should not replace professional medical advice. If you or a loved one has been hospitalized with COVID-19, discuss calcium levels and any other health concerns with your doctor. Do not attempt to change calcium intake or supplementation based on this study without consulting your healthcare provider, as both too much and too little calcium can be harmful. This study was conducted in a specific hospital setting and may not apply to all populations or healthcare systems.