Laboratory features throughout the disease course of influenza A (H1N1) virus infection.

Background: Influenza has emerged every year but a complete profile of laboratory indices throughout the disease course remains unknown. Methods: Clinical data was collected from 28 confirmed cases of the pandemic influenza H1N1 2009. The levels of serum iron (Fe), carbon dioxide combining power (CO2-CP), total complement hemolytic activity (CH50), C-reactive protein (CRP), and white blood cell (WBC) and differential count were analyzed. Results: Major laboratory abnormalities recorded for patients upon admission were lymphopenia (96.4%), eosinopenia (50.0%), hypoferremia (92.9%), decreased levels of serum CO2-CP (60.7%), increased levels of serum CRP (84.6%) and serum CH50 (71.4%). The serum iron and CO2-CP concentration and the counts for lymphocytes, eosinophils, and basophils were significantly increased four days after sickness was noticed compared with the first three days of illness (p < 0.05). The total WBC and neutrophil counts were significantly decreased four days after onset of illness compared with the counts over the first three days (p < 0.05). The monocyte count and CRP concentration was significantly decreased 7 days after onset of illness compared with first 3 days after illness onset (p < 0.05). The serum CH50 concentrations were higher than the normal range during disease course and significantly elevated 7 days after onset of illness compared with the first 6 days after illness onset (p < 0.05). Conclusions: The serum levels of iron, CO2-CP, CH50, CRP, and WBC and differential count were significantly varied during the whole pandemic influenza (H1N1) 2009. The development of WBC count in patients with influenza may be an effective predictor for severity of illness.