Thyroid function in Fabry disease before and after enzyme replacement therapy

AM: Patients with Fabry disease (FD), a genetic disorder caused by lysosomal a-galactosidase-A enzyme deficiency and characterized by a systemic accumulation of globotriaosylceramides, present high prevalence of subclinical hypothyroidism. The pathogenic mechanism is thought not to be related to anti-thyroid autoimmunity and may be dependent by intra-thyroid lipid accumulation. In this study, it was investigated whether thyroid function recovers in FD after long-term enzyme replacement therapy (ERT).

Study population included 14 FD patients (7 females, 7 males, aged 21-62 years) and 14 sex- and age-matched normal subjects. Thyroid function was evaluated in each patient at baseline and after the beginning of ERT with rh-a-galactosidase-A (1 mg/kg/BW every 2 weeks) for three years.

TSH levels were higher in FD patients than in controls (P<0.05). In FD patients, TSH levels were higher before than after ERT (1.9±0.2 vs 1.2±0.2 mU/L, P<0.01) while fT3 and fT4 levels were normal at baseline and unchanged after ERT. At baseline, TSH levels were >3 mU/L in three patients and normalize after ERT. Anti-Tg and/or anti-TPO titres were positive in 14% of patients and 21% of controls. After ERT, the rate of autoimmunity was unchanged. At the thyroid ultrasonography, a slight hypoechoic pattern was found in 71% of patients at baseline and decreased to 43% after ERT.

Primary hypothyroidism in FD patients is reverted after long-term ERT. A screening of thyroid function and periodical re-evaluation during ERT is mandatory in all FD patients.