Frequency of High Serum Creatine Phosphokinase (CPK) Levels in Hospitalized Patients with Influenza in 2019

Influenza is one of the leading causes of respiratory illness in children and adults with underlying disease and the elderly. The virus kills large numbers of people annually, and dangerous types of the virus are associated with pneumonia and complications. Muscle pain is one of the most common findings in this disease, which is associated with myoglobinuria and increased levels of creatine phosphokinase (CPK). Patients with high CPK levels are associated with more complications and a higher risk of hospitalization. There has been a lot of research on the high levels of CPK in these patients, but the association of this enzyme in the blood of hospitalized patients with influenza has not been done and it is important to pay attention to the levels of this enzyme in hospitalized people. Serum CPK levels in the flu can be used as a diagnostic marker and predict the effects of the flu. Therefore, the aim of this study was to evaluate the level of CPK in patients with influenza and its differences in different ages.

In this descriptive-analytical study, 264 patients with influenza resulting in hospitalization with an age range of one month to 90 years who were referred to Hazrat Ali Asghar and Hazrat Rasoul Akram Hospital in Tehran in autumn and winter of 1398, were Were examined. The clinical signs of influenza were evaluated in these patients and the frequency of lymphopenia, thrombocytopenia, neutropenia, myoglobinuria, positive blood culture and blood CPK level were measured in vitro. The relationship between influential variables such as myalgia and myoglobinuria and platelet status with high CPK levels was investigated. The obtained data were analyzed by SPSS software version 23.

The mean age of patients was 24.99 years. 54.2% were male. Prevalence of clinical symptoms of patients based on age groups showed that 176 (66.7%) had chills, 179 (67.8%) had myalgia, 115 (43.5%) had pharyngitis, 242 (98.4%) Cough, 119 patients (45%) had sputum, 58 patients (22%) had headache, 66 patients (25%) had shortness of breath and 68 patients (25.6%) had diarrhea. Among these, the highest and lowest prevalence of myalgia were in the age group of 21-40 years and children under 5 years, respectively, which was statistically significant (P = 0.027). There was also a significant difference in the prevalence of pharyngitis (P ˂0.001), sputum (P = 0.004) and shortness of breath (P ˂0.001) in patients. CPK levels were about 50% higher than normal and did not differ between age groups and sexes. Lymphopenia, thrombocytopenia and neutropenia had a prevalence of 41%, 25% and 20%, respectively. Myoglobinuria had a prevalence of 82%, which was more common in the under-5 age group. In the group with normal CPK, the prevalence of myoglobinuria was nearly 30% higher. Also, the prevalence of high CPK in the group with myoglobinuria was almost 35% higher than the group without it, which indicates the relationship between the prevalence of high CPK and myoglobinuria (P = 0.02). There was a significant relationship between patients' blood platelet status and high or normal CPK (P = 0.01). The prevalence of myalgia in the group with high CPK was 52% higher than the group without myalgia and in the group with myalgia, the prevalence of high CPK was 16% higher and the prevalence of myalgia symptom was statistically significant (P = 0.004). Positive blood cultures were higher in adults and the elderly than in youth and children, and among the clinical signs, CPK was associated only with myalgia.

High levels of CPK were observed in half of the patients and our findings showed that high levels of CPK were significantly associated with myalgia and myoglobinuria and platelet status. This indicates that the increase and decrease of this enzyme can affect the fate of the disease. It is suggested that future studies investigate the association of CPK levels with lymphopenia and leukopenia and immune cells. Examination of CPK levels in future patients can be effective in identifying the risk factor for disease severity and help in better treatment and reduction of disease complications.