IN NEW-ONSET INSULIN-DEPENDENT DIABETIC-PATIENTS THE PRESENCE OF ANTITHYROID PEROXIDASE ANTIBODIES IS ASSOCIATED WITH ISLET-CELL AUTOIMMUNITY AND THE HIGH-RISK HAPLOTYPE HLA DQA1-ASTERISK-0301-DQB1-ASTERISK-0302

In 157 new onset IDDM (104 men, 53 women, ages 10-39 yr) anti-thyroid peroxidase anti-bodies (anti-TPO) were assayed with a specific immunol ogical test. Values greater than 100 U ml(-1) were considered positive . Seventeen per cent of the patients were positive (32% of the women v ersus 10% of the men, p < 0.001). Eighty-five per cent of the anti-TPO + patients have a positive titre of islet-cell antibodies (ICA greater than or equal to 12 JDFU) versus 64% of the anti-TPO-patients (p < 0. 05). When patients were subdivided in a young (10-25 yr) and an older age group (26-39 yr) this association was also true for ICA greater th an or equal to 50 JDFU and valid for insulin autoantibodies (IAA) at l ow (greater than or equal to 0.7%) and high risk (greater than or equa l to 1.5%) (p < 0.005) in the second group. The median of the TSH conc entration was not different between anti-TPO+ and anti-TPO- when the g roup is considered as a whole. In the anti-TPO+ men (26-39 yr) TSH was however significantly greater (1.55 mu U ml(-1), range 0.74-8.5 versu s 1.4 mu U ml(-1), range 0.21-3.5, p < 0.0001) when compared to the an ti-TPO-men of the same age group. The haplotype HLA DQA10301-DQB1*030 2 was more frequent in the anti-TPO+ (39%) than in the anti-TPO- (23%) patients (p < 0.02) for the age group 26-39 yr but not for the age gr oup 10-25 yr. The other diabetes susceptibility haplotype DQA10501-DQ B10201 was less frequent in anti-TPO+ patients. In conclusion we sugg est that thyroid auto-immunity must be part of the initial screening o f IDDM especially when patients are older at clinical onset of the dis ease.