Patients with insulin-dependent diabetes mellitus (IDDM) have a 6-20% incidence of thyroid autoantibodies, depending upon the population studied /1-5/.It has been reported that 45% of IDDM patients with antimicrosomal antibodies (MCHA) may develop thyroid dysfunction /4/. In adult diabetics there is an increased prevalence of subclinical hypothyroidism, unrelated to the presence of autoantibodies, diagnosed by basal TSH and T 4 values /6/ and an exaggerated response of TSH to TRH /7/.The aims of the present investigation were to study children with IDDM for a) the evolution of the anti-thyroid antibodies during a 12-18 month follow-up period and b) changes in thyroid function as assessed by T 4 and T 3 levels and the TSH response to TRH.
SUBJECTS AND METHODSNone of the patients had a goiter or clinical signs of thyroid dysfunction at the diagnosis of diabetes. Each patient was treated with at least 2 injections of insulin per day, and none was in ketoacidosis at the time of the test. The patients were randomly divided into two groups. Group 1 consisted of 77 patients with IDDM (41 females and 36 males) with a mean age of 12.3 years (range 4-18.9 years) and a mean duration of the disease of 59.4 months. In this group, we investigated the presence of antithyroglobulin (TGHA) and MCHA antibodies and measured the basal values of T 4 , T 3 , Free T 4 (FT 4 ), TSH and the TSH response to i.v. TRH.All patients were re-examined clinically 12-18 months after the first test. In 19 of them the antibody titer and the TSH response to TRH were again determined.Group 2 consisted of 23 patients with IDDM (13 females, 10 males) with a mean age of 13.4 years (range 5.8 to 18.1 years) and with a mean duration of the disease of 73.8 months. In these patients, basal blood values of T 4 , T 3 and Hb A] were longitudinally (2-3 times) monitored during 12-18 months. Five Mg/kg TRH (Roche, Basel) was intravenously injected as a bolus: blood samples were withdrawn just before the TRH injection (time 0) and 20, 30, 60 and 90 min. afterwards.TGHA and MCHA were detected in the plasma with the method of passive hemoagglutination (thymune-T -Wellcome, Beckenham, UK and Fujizoki, Tokyo, Japan respectively). TSH, T 4 , T 3 , FT 4 and HbAiwere determined in the blood respectively by RIA and by microchromatography as previously reported /8/.
RESULTS
Group 1:MCHA were present in 11.7% and TGHA in 5.2% of the patients. In a control study carried out in 197 normal subjects, age and sex matched with our patients, MCHA were present in 3% and TGHA in 0.5% of the subjects. The nine patients with MCHA (Table I) (6 females and 3 males) were older than 10 years. In the patients with MCHA both basal TSH levels (3.3 ± 1.3 μΙΓ/πι1;Χ ± SD 9) and peak levels of TSH after TRH (21.3+7.0 μυ/ml) were statistically not different from the patients without VOL. 1, NO. 2&3, 1985 185 Brought to you by | University of Arizona Authenticated Download Date | 7/29/15 7:31 PM
