Hematologic parameters in patients with COVID‐19 infection

As of 28 February, 2020, Singapore had 96 confirmed cases of COVID‐19 infection. SARS‐CoV‐2 was confirmed by Real Time Reverse Polymerase Chain Reaction (RT‐PCR), performed on respiratory samples of these patients. A majority of 69 out of these 96 patients were treated at the National Centre for Infectious Diseases (NCID).

A new study presents a detailed analysis of the hematological parameters of the COVID‐19 patients at the NCID.

In this way, the study also revealed that on admission, most patients had a normal Complete Blood Count (CBC) ―normal Hemoglobin (Hb), White Blood Cells (WBC) and Platelet Count (PC)―, and Lactate Dehydrogenase (LDH). Also, no patient presented moderate or severe thrombocytopenia that is frequently observed in other viral illnesses such as dengue fever which is endemic in that region.

However, 28% of all patients presented with lymphopenia ―low Absolute Lymphocyte Count (ALC)―. This number is significantly smaller compared to 63% of patients in Wuhan, China, and 42% of patients outside of Wuhan who presented with lymphopenia. This disparity in numbers may in part be reflective of the extent of epidemiological data available within the surveillance pyramid in those regions. Those requiring ICU care had a lower lymphocyte counts and higher LDH. These were findings also reported on the characteristics of COVID‐19 patients in Wuhan, China. Besides, lymphopenia has been well described in retrospective analysis of patients in Hong Kong and Singapore afflicted with SARS‐CoV in 2003, and was associated with adverse outcomes and ICU stay.

Notably, ICU patients tend to develop neutrophilia during the hospitalization with a median peak Absolute Neutrophil Count (ANC) of 11.6 × 109/L, compared to 3.5 × 109/L in the non‐ICU group. The ICU group also had a peak LDH which was significantly higher than the non‐ICU group.

This review is a reflection of real‐life clinical setting wherein a proportion of asymptomatic patients (admitted from positive RT‐PCR results during contact tracing) may not have significant anomalies on their CBC at presentation. This may result in lower hematological indices on admission as those patients were already in critical condition.

In conclusion, the study showed that on admission, older age, lymphopenia and raised LDH were associated with ICU admissions. Patients who were transferred to the ICU had a lower ALC, lower Absolute Monocyte Count (AMC) and lower Hb, and higher peak Absolute Neutrophil Count (ANC) and peak LDH levels as compared to patients who did not require ICU stay.

Link to the paper: https://doi.org/10.1002/ajh.25774

Editorial Disclaimer: information published during the 2020 COVID-19 pandemic may be updated frequently to reflect the dynamic nature of current understanding.

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