Hector Osorio 21 May 2020

COVID 19 is a novel disease caused by the SARS-cov-2 virus that is currently spreading around the world and is characterized by being highly infectious, causing symptoms mostly associated with the respiratory and gastrointestinal system and leading to a deadly inflammatory response in (2-3)% of cases [1].

The international media has been reporting on our capability for detecting or predicting the behavior of this disease, which at the moment continues to develop but is still lacking. Meanwhile, the medical community is working on indirect ways to track the development of COVID 19 patients using more traditional methods that are already available and do not require expensive new reagents or technologies.

Lab results were naturally the first tool to explore in the study of how this new disease behaves in different individuals. Ideally, by detecting a strong correlation between some of the parameters most commonly evaluated by these routine tests (like white blood cell count in the hematology test, for example), doctors could gather a list of good indicators that could help them improve the care provided to patients and even prevent the development of the disease into its most deadly forms.

In this article we will point out some of the most promising parameters being studied in COVID 19 patients today that can be analyzed with already available lab tests and that could potentially save many lives and/or improve the quality of care provided in healthcare facilities. Remember though, this is a new virus so things are changing daily.


This parameter is not obtained with laboratory tests, however, is so important and heavily supported by the scientific community that it would be careless to omit it here.

It is well-known that COVID 19 tends to be more dangerous for the elderly. People older than 67 years are at a much higher risk of manifesting the most severe symptoms and represent a large proportion of the (2-3)% mortality rate. This reveals them as the main vulnerable population, which indicates that they will need to be specially protected against infection and that our treatment and handling of the elderly when infected should be different than how we handle younger patients [2].

IL-6 and D-Dimer

IL-6 is a pro-inflammatory cytokine, which means that it mediates a number of processes involved with the development of an inflammatory response. In other articles we have mentioned the importance of these cytokines in the most critical stages of covid-19, however, recent evidence suggests that by monitoring this parameter, doctors could help predict which patients are more likely to experience severe symptoms and organize their efforts to prevent the worst outcomes [3].

D-dimer is an important indicator for the late stages of coagulation and high levels can be found in individuals with a greater tendency to form blood clots than normal. In severe cases, COVID 19 patients develop coagulation problems like thromboembolism, which makes D-dimer an especially important parameter to keep track of [3,4].

Some researchers consider that studying both parameters (in tandem or in parallel) is a very good tool since (depending on how they are measured) this method can predict which patients will develop severe symptoms with as much as 93.3% sensitivity and 96.4% specificity [3].

These parameters become valuable as predictive factors when: IL-6> 24.3 pg/ml and/or D-dimer >0.28 µg/L [3].

C reactive protein, IL-8 and TNF-α

These 3 parameters are also strongly associated with the inflammatory response. Since most complications from COVID-19 are caused by an extreme inflammatory process, it is no surprise that indicators such as these (which are directly correlated to the intensity of the response) can be used to follow how each patient evolves [2,5].

In the case of C reactive protein, values over 30,7 ng/ml tend to be associated with more severe outcomes [2].

Vitamin D

Recent evidence points to a very curious connection between COVID-19 and Vitamin D deficiency [6]. In a previous article we explored the importance and sources of this vitamin so we’ll skip right to its relevance in the context of this new disease.

Some researchers consider that Vitamin D could be used to treat COVID 19 patients. This approach is supported by the observation that countries where people could be more exposed to the sun tended to have a lower death rate than colder/”darker” countries and by the evidence pointing at severe Vitamin D deficiency as a relevant factor that predisposed individuals to some of the worst manifestation of this disease [6].

Although more studies are required, some authors are considering incorporating Vitamin D supplementation as treatment for patients with low levels of this vitamin. 10000 IU/day of Vitamin D have been recommended to sustain vitamin levels over (40-60) ng/ml [6].

It seems important to also mention that Vitamin D is thought to help the body fight viral infections by (among other things) regulating the immune response and prevent cytokine storms [6].

Vitamin K

COVID 19 causes coagulation problems in severe patients. Some studies have the theory that important factors related to coagulation such as Vitamin K could provide important evidence for the proper diagnosis and treatment of patients [7].

Vitamin K is a factor that promotes coagulation and it seems to decrease significantly in critical COVID 19 patients. At the moment, Vitamin K supplementation has not been adopted as a common treatment and more evidence is needed to determine how effective that approach would be in severe cases [7,8].

Normal Vitamin K levels exist within the range of (0.2-3.2) ng/ml. This nutrient can be found mostly in leafy green vegetables like lettuce [8].

White blood cell (WBC), Lymphocytes (LC) and Neutrophils (N)

Some blood parameters become altered in the presence of most viral infections and although they alone cannot be used to specifically diagnose or treat them, they should still be considered as early warning signs.

WBC or leukocytes are extremely important cells that directly act as part of the immune system and therefore become affected when an infection is present. LC refers to a sub-group of the WBC that are more associated with the mechanisms that the body uses to adapt and attack “unknown” infectious agents [9].

WBC and LC drop considerably as part of the development of several different diseases and this is also the case for COVID 19. Interestingly, some studies say that both mild and critical patients have this symptom and it does not seem to have a direct correlation to the severity of the disease [2, 9].

Neutrophils are also a sub-group of leukocytes; however, these are associated with the more immediate responses that the immune system has against infections. Is quite common to register a sudden increase in the number of these cells when an infection has been detected by the body [2, 9].


Several enzymes become altered in patients with COVID-19.

Lactate dehydrogenase (LDH), aspartate aminotransferase (ALT) and alanine aminotransferase (AST) increase considerably in these patients and some studies propose that they (together with other parameters already mentioned in this article) could be used as an alternative method for the diagnosis of COVID 19 [9].

ALT and AST are mainly related to the function of the heart, liver and kidney while LDH is important for the basic functions of almost all living cells. High levels are traditionally linked to organ or tissue damage, however, whether these parameters directly signal loss of liver function in COVID 19 patients is still under debate [9, 10].

Is important for us to remind you that COVID-19 is still a very new disease and our understanding of the interactions between the human body and this virus is still developing, therefore, a lot of information is still unknown and what we do know changes quickly. Consult with your doctor before interpreting your own lab tests.

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About the Author:
Hector Osorio is a cell biologist, research assistant and science/health content writer. He loves complex topics related to life sciences like cancer, viral infections and aging. He graduated from Central University of Venezuela Faculty of Sciences and worked as a research assistant for the Center of Experimental Medicine of the Venezuelan Center for Scientific Research (IVIC) for 5 years.


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  • [7] Dofferhoff, A. S., Piscaer, I., Schurgers, L. J., Walk, J., Van den Ouweland, J. M., Hackeng, T. M., … Janssen, R. (2020). Reduced vitamin K status as a potentially modifiable prognostic risk factor in COVID-19. doi:10.20944/preprints202004.0457.v1
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