Bevacizumab-Induced Hypothyroidism: A Case Study

This case study highlights a 60-year-old woman with pre-existing primary hypothyroidism who experienced worsening thyroid function while undergoing chemotherapy with bevacizumab for metastatic duodenal carcinoma. Bevacizumab, a monoclonal antibody targeting VEGF, is not commonly associated with thyroid dysfunction, unlike tyrosine kinase inhibitors. However, in this case, the patient's TSH levels increased significantly, indicating worsened hypothyroidism, which improved after adjusting her levothyroxine dosage and temporarily halting bevacizumab. The study suggests that bevacizumab may affect thyroid function, necessitating monitoring of thyroid labs during VEGF inhibitor therapies. Further research is needed to understand the mechanisms and prevalence of this adverse effect.