Transient Elevation of CA 19-9 Due to Cessation of Levothyroxine in a Patient with Hashimoto’s Thyroiditis

ABSTRACT

Serum CA 19-9 (carbohydrate antigen 19-9) is a tumor marker with monosialoganglioside structure. Its levels are measured frequently for screening purposes in daily practice by physicians, while its main application is in the study of tumor recurrence and the follow-up of the recurrences. Although significant elevation in the levels of CA 19-9 indicates malignancy, an underlying malignant disease may not always be determined, and benign pathologies may also be observed. A 45-year-old female patient who was undergoing a follow-up for Hashimoto’s thyroiditis applied to our clinic with complaints of fatigue, tiredness, and hair loss. Elevations in the levels of both thyroid-stimulating hormone (TSH) and CA 19-9 were observed. The levels of TSH and CA 19-9 were observed to be normal after the patient was treated for hypothyroidism, and the results of the analysis conducted for malignancy were also determined to be normal. On the basis of the present case study, we propose that hypothyroidism should be considered while making a differential diagnosis for patients with elevated levels of CA 19-9.