Thyroid function and anti-thyroid antibodies in Iranian patients with type 1 diabetes mellitus: influences of age and sex

ABSTRACT

Type 1 diabetes mellitus is frequently associated with autoimmune thyroid disease [ATD].Genetic susceptibility for autoantibody formation in association with ATD and type 1 diabetes mellitus has been described with varying frequencies, but there is still debate about its prevailing situation in Iran. We have therefore investigated the prevalence of anti-thyroid peroxidase [anti-TPO] and anti thyroglubolin [Anti TG] antibodies in type 1 diabetic patients, and compared the effect of age and sex on the thyroid autoimmunity in patients with type 1 diabetes mellitus in Iran. Ninety one subjects with type 1 diabetes mellitus and one hundred and sixty three unrelated normal controls under the age of thirty years were recruited for the detection of anti-TPO and anti-TG. Radio Immuno Assay and chemiluminescence methods were used for anti-TPO and anti-TG detection respectively. Among 91 type 1 diabetic patients, 36 [39.6%] were positive for anti-TPO and 27[30%] were positive for antiTG. Anti-TPO antibodies were detected only in 6.7% of control group. Comparing with those without thyroid autoimmunity, there was a female preponderance for the type 1 diabetic patients with thyroid autoimmunity [female male, 2814 vs. 2820 respectively]. Among the type 1 diabetic patients those with thyroid autoimmunity, tended to be older [p 0.04] and to have higher TSH concentration [p 0.03]. Patients with high anti-TPO levels had longer duration of diabetes [P 0.02]. The presence of anti-TPO in 39.6% of our type 1 diabetic patients comparing with 8.5% of normal subjects confirmed the strong association of ATD and type 1 diabetes mellitus