Introduction: Subclinical thyroid dysfunction (STD) is rapidly rising worldwide and reported among medical staff to about 30% due to high work stress and night shifts affecting the circadian system leads to hormonal irregularities. Aim of Work: To assess the prevalence of subclinical thyroid dysfunction and its associated factors among healthcare workers. Materials and Methods: A cross-sectional study was carried out during the period from September 2023 to February 2024 among a random sample including: Group I: 118 participants of healthcare workers at Menoufia University Hospitals, Shebin Al-
Kom City, Egypt and Group II: control group (118) who were attending outpatient clinic of Family Medicine at the same hospitals and were matched in age and sex with group I. A pre-designed questionnaire was answered by each participant and blood samples were taken for assessment of free tri-iodothyronine (FT3), free thyroxine (FT4) and serum thyroid-stimulating hormone (TSH) level. Results: The prevalence of STD was 33.1% among healthcare workers (HCWs) versus 11.9% among controls with overall prevalence of 22.5%. Female gender, smoking, comorbidities, working >8 hours daily
and obesity were more frequent among those with STD 79.5%, 15.4%, 38.5%, 87.2% and 46.2% versus only 58.2%, 3.8%, 13.9%, 69.6% and 11.4% of those without STD (p=0.037, 0.025, 0.005, 0.038 and 0.002; respectively). Logistic regression was performed to show the effects of the studied risk factors on the likelihood of STD occurrence and it
was statistically significant p < 0.05. Conclusion and Recommendations: STD was more prevalent among HCWs. Screening of all HCWs for STD by TSH testing and analyses of the work environment to assess all risk factors associated with this disorder are suggested. Repeating the screening of TSH should be done after 3 months in cases of subclinical
hypothyroidism for diagnosis of overt hypothyroidism.