Incidence of thyroid disorders in mixed cryoglobulinemia: Results from a longitudinal follow-up.

No study has evaluated the incidence of new cases of thyroid autoimmunity (AT) and dysfunction (TD) in hepatitis C-associated mixed cryoglobulinemia (MC) patients. We aimed to evaluate the incidence of new cases of AT and TD in a wide group of MC patients vs. age- and gender-matched controls from the same geographic area. After exclusion of MC patients with TD at the initial evaluation, the appearance of new cases of TD was evaluated in 112 MC patients and 112 matched controls, with similar iodine intake (median follow-up 67months in MC vs. 78 in controls). A high incidence (P<0.05) of new cases of hypothyroidism, TD, anti-thyroperoxidase antibody (AbTPO) positivity, appearance of a hypoechoic thyroid pattern, and thyroid autoimmunity in MC patients vs. controls was shown. A logistic regression analysis showed that in MC, the appearance of hypothyroidism was related to female gender, a borderline high initial thyroid-stimulating hormone (TSH), AbTPO positivity, a hypoechoic, and small thyroid. In conclusion, we show a high incidence of new cases of AT and TD in MC patients. MC patients at high risk (female gender, a borderline high initial TSH, AbTPO positivity, a hypoechoic, and small thyroid) should have periodically thyroid function follow-up.