Thyroid function and thyroid autoimmunity in patients with type 1 diabetes mellitus AbdelRahman Radaideh, MD, Mohammed El-Khateeb, MD, Anwar M. Batieha, MD, Abeer S. Nasser, BSc Lab, Kamel M. Ajlouni, MD, PhD.
ABSTRACT Objective: An association between diabetes mellitus and autoimmune thyroid disease is well known. We have investigated the prevalence of thyroid dysfunction and autoimmunity in type 1 diabetic patients. Methods: Seventy-nine type 1 diabetic patients were recruited in the study, and underwent complete investigations for thyroid function, which included free thyroxine, free triiodothyronine, and thyroid stimulating hormone, of those only 64 patients had performed thyroid autoantibodies (TAb); antithyroid peroxidase antibodies (TPOAb) or antimicrosomal antibodies and thyroglobulin antibodies (TgAb). They were compared with 127 healthy subjects matched for sex and age. This study was carried out at the National Center for Diabetes, Endocrinology and Genetics, Jordan University, Amman, Jordan between 2000 and 2001.
subclinical hypothyroidism, whereas the other 3 had overt hypothyroidism and were on thyroxine replacement therapy. In the control group, 6 (4.7%) subjects were diagnosed as subclinical hyperthyroidism. There was a significant difference in thyroid function variables between diabetics and controls. Among type 1 diabetic patients, 7 (9.2%) had thyroid autoantibodies, 5 with positive TPOAb only and 2 with positive TAb; TPOAb or antimicrosomal antibodies and TgAb; compared with 8 (6.3%) in the control group, 4 with positive TPOAb only and 4 with positive TAb; TPOAb or antimicrosomal antibodies and TgAb P=0.68. Conclusion: Biochemical thyroid dysfunction and thyroid autoimmunity were evident in type 1 diabetics who were apparently euthyroid, with no significant difference between diabetics and controls.
Results: In the diabetic group, 7 cases (8.9%) of thyroid dysfunction were detected, 4 of these were diagnosed as
he association between type 1 diabetes mellitus T (T1DM) and autoimmune thyroid disease has long been recognized. In several studies of children and 1
adults with T1DM, a high prevalence of thyroid autoantibodies (TAb) (8-44%) has been found as an indicator of thyroid autoimmune disease. 1-7 Most of those antibody-positive diabetic patients were clinically and
Saudi Med J 2003; Vol. 24 (4): 352-355
biochemically euthyroid. It is uncertain how many of them will later develop thyroid dysfunction. The thyroid antibodies detected in previous studies have primarily been against thyroglobulin and microsomal antigens. It is now possible to measure the more sensitive and antigen-specific anti-thyroid peroxidase antibodies (TPOAb).8,9 However, TAb does not always appear in
From the National Center for Diabetes Endocrinology and Genetics (Radaideh, Nasser, Ajlouni), Department of Pathology (El-Khateeb), Jordan University and the Department of Public Health (Batieha), Jordan University of Science and Technology, Amman, Jordan. Received 7th September 2002. Accepted for publication in final form 16th November 2002. Address correspondence and reprint request to: Dr. Kamel M. Ajlouni, National Center for Diabetes Endocrinology and Genetics, PO Box 13165, Amman 11942, Jordan. Tel. +962 (6) 5353374. Fax. +962 (6) 5353376. E-mail:
[email protected]
352
Thyroid function and thyroid autoimmunity ... Radaideh et al
the serum of patients with autoimmune thyroid diseases.10 In the present study, we determined the prevalence of thyroid dysfunction and TAb abnormalities in T1DM patients compared with age and sex matched healthy controls. The aim of the present study was to assess the prevalence of thyroid dysfunction and autoimmunity in T1DM Jordanian patients attending the National Center for Diabetes, Endocrinology and Genetics in Amman, Jordan. Methods. All patients with T1DM receiving care at the National Center for Diabetes, Endocrinology and Genetics, Jordan University, Amman, Jordan between 2000 and 2001, were eligible for the study. A total of 79 patients were recruited in the study; 41 females (60%) and 38 males (40%) with a mean age of 19.6 ± 9 years (range 3-43) and a mean duration of diabetes of 5.96 ± 6.64 years (range 1-32). Three patients were known cases of hypothyroidism and were on L-thyroxine treatment. The age and sex matched control group, residing in the same geographical area, included 127 healthy subjects. The mean age of the control group was 20.9 ± 5.5 years (range 7-30). At the time of the study, none of the participants had acute or recent illness nor were receiving any drugs affecting thyroid function. All participants underwent complete physical examination. Venous blood samples were withdrawn and assayed for determination of thyroid function: free thyroxine (FT4), free tri-iodothyronine (FT3), thyroid stimulating hormone (TSH), anti-TPOAb or antimicrosomal antibodies (AMAb), thyroglobulin antibodies (TgAb) and glycosylated hemoglobin (HbA1c). Tests were either directly analyzed from venous blood samples or serum was frozen at -20ºC until analysis. All participants gave informed consent and the study was approved by the ethical committee of the Center. Biochemical measurements. Serum free thyroxine (normal range 9.1-23.8 pmol/l), serum FT3 [normal range 2.58-5.44 pmol/L] and serum TSH (normal range 0.40-5.0 mU/L) were determined by enzyme linked immunoassay (ELISA) (microparticle enzyme immunoassay, Abbott Lab United States of America). Serum anti-TPOAb (normal range
