Transient elevation of serum tumor markers in a patient with hypothyroidism

We report a case of a 66-year-old woman admitted to our hospital for examination and treatment of uterine and rectal prolapse, pleural and pericardial effusion, and ascites. On further examination, she was diagnosed with hypothyroidism. Test results showed markedly elevated concentrations of serum carcinoembryonic antigen (CEA) and carbohydrate antigen 125 (CA 125). We consequently performed multiple imaging studies, none of which detected a malignancy. Hormonal replacement therapy with levothyroxine was started, and the pleural and pericardial effusion and ascites gradually abated. Concentrations of serum CEA and CA125 also decreased gradually after therapy with levothyroxine. These findings indicate that in patients with hypothyroidism, elevated CEA and CA125 levels do not necessarily indicate malignancy. Conversely, in any patient with elevated serum CEA and/or CA125, hypothyroidism should be considered in the differential diagnosis.