Abstract
INTRODUCTION: Telogen effluvium (TE) is one of the causes of non-scarring hair loss that occurred commonly 2-3 months after a triggering factor. It was reported that the incidence of TE increased during the COVID-19 (coronavirus disease 2019) pandemic. However, to date, there is no study evaluating the status of COVID-19 before the onset of hair loss in patients with TE. The aim of this study is to evaluate the patients with TE whether they had COVID-19 or not before the onset of their hair loss and to compare the demographic and clinical characteristics and laboratory parameters of those with and without a history of COVID-19. METHOD: We conducted an observational cohort study of TE patients. The diagnosis of TE depended on anamnesis and physical examination of the patients. Also, hair pull test was performed. Demographic data and the results of COVID-19 real-time polymerase chain reaction (RT-PCR) were recorded from the electronic medical records. RESULTS: Totally, 181 patients with TE were included in the study. Sixty-four of patients (35.4%) had been diagnosed with COVID-19 before the hair loss started. The median duration of development of hair loss was 2 months (range 1-11 months, IQR 3) after COVID-19 diagnosis. In this group, 87.5% of patients (n = 56) had acute TE and 12.5% of patients (n = 8) had chronic TE. The rate of acute TE and the use of vitamin supplements were ignificantly higher (p < 0.001 and p = 0.027, respectively) and the monocyte count in peripheral blood was lower (p = 0.041) in the group diagnosed with COVID-19. DISCUSSION AND CONCLUSION: It was stated that monocytes and macrophages infected by SARS-CoV-2 can produce pro-inflammatory cytokines that play a crucial role in the development of COVID-19-related complications. Also, it was suggested that the number of monocytes tends to be lower in the late recovery stage. The lower monocyte count in patients with a history of COVID-19 in our study may be related to evaluating the patients in the late period of recovery and the migration of circulating monocytes to hair follicles. The history of COVID-19 must be questioned in patients with TE. It should be kept in mind that hair loss that develops after COVID-19 may be presented as chronic TE form too. The exact mechanisms of hair loss induced by COVID-19 are not fully explained; the roles of monocytes on the hair follicles may be one of the responsible mechanisms.