Assessment of Thyroid Hormone Levels and the Potential Risk of Hypothyroidism in Healthcare Workers Exposed to Low-Dose Ionizing Radiation
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Background: Healthcare professionals working in radiology and nuclear medicine may experience repeated occupational exposure to low-dose ionizing radiation, while the thyroid is a radiosensitive endocrine organ. Evidence concerning thyroid dysfunction among occupationally exposed healthcare workers remains limited in Pakistan. Objective: To assess thyroid hormone profiles and the association between occupational radiation exposure and hypothyroidism among radiology and nuclear medicine personnel. Methods: This cross-sectional study included 44 healthcare professionals from the Institute of Nuclear Medicine and Oncology, Lahore. Occupational information and exposure history were collected through a questionnaire, annual radiation exposure categories were obtained from personal dosimetry records, and serum thyroid-stimulating hormone (TSH), free thyroxine (FT4), and free triiodothyronine (FT3) were assessed. Results: Overall, 13/44 (29.5%) participants were classified as having hypothyroidism. Hypothyroidism occurred in 2/17 (11.8%) radiology personnel and 11/27 (40.7%) nuclear medicine personnel (exact p=0.0496). Prevalence increased across exposure-duration categories from 0% at 1–5 years to 52.6% at ≥16 years (exact p=0.0385). Hypothyroidism occurred in 3/27 (11.1%) participants within the normal radiation-exposure category and 10/17 (58.8%) in the higher-than-normal category (exact p=0.0016; crude prevalence ratio 5.29, 95% CI 1.70–16.53). TSH distributions differed significantly between exposure groups (p=0.0026), whereas FT4 and FT3 category distributions did not reach statistical significance. Conclusion: Higher recorded occupational radiation exposure and longer exposure duration were associated with a greater prevalence of hypothyroidism in this sample. The cross-sectional design does not establish causation, but the findings support continued occupational dosimetry, radiation-protection measures, and appropriate thyroid health surveillance.
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