Rising frequency of autoimmune thyroid disease
with time in type 1 diabetes mellitus
(July 2003)
The background of
the study. Patients with type 1 diabetes mellitus have an
increased risk of autoimmune thyroiditis, as defined by high serum
antithyroid antibody concentrations or thyroid ultrasonography.
In this study these tests were repeated in children and adolescents
with type 1 diabetes three years after initial study.
How the study was done. In 1997,
serum antithyroid peroxidase antibodies, thyrotropin, and thyroxine
were measured, and thyroid ultrasonography was done in 105 children
and adolescents with type 1 diabetes and 105 age- and sex-matched
normal subjects. These tests were repeated in 2000 in 101 (96 percent)
of the diabetic children and adolescents (47 girls, 54 boys; median
age, 16 years; median duration of diabetes, 8 years).
The results of the study. Five of
the 101 patients with diabetes (5 percent) had hypothyroidism initially;
at follow-up three more patients had hypothyroidism. Four of these
eight patients had a high serum antithyroid peroxidase antibody
concentration, and all had attenuated echoes on thyroid ultrasonography.
At base line, 13 patients (13 percent) had a high serum antithyroid
peroxidase antibody concentration. At follow-up, 10 patients had
higher concentrations and 3 patients had lower (but still high)
concentrations. No patient who had a normal serum antithyroid peroxidase
antibody concentration at base line had a high concentration at
follow-up.
The median thyroid volume at base line was 9 ml in the patients
and the normal subjects. At follow-up, it was 11 ml in the patients.
Some ultrasonographic abnormality (usually decreased echoes) was
present in 42 patients (42 percent) at base line and in 49 patients
(48 percent) at follow-up; 33 (33 percent) had an abnormality at
both times, 16 changed from normal to abnormal, and 9 changed from
abnormal to normal. Ultrasonography was abnormal in 77 percent of
patients with high serum antithyroid antibody concentrations and
44 percent of those with normal concentrations.
The conclusions of the study. The
frequency of biochemical, serologic, and ultrasonographic abnormalities
indicative of chronic autoimmune thyroiditis increases with time
in children and adolescents with type 1 diabetes.
The original article. Hansen D,
Bennedbaek FN, Hoier-Madsen M, Hegedus L, Jacobsen BB. A prospective
study of thyroid function, morphology and autoimmunity in young
patients with type 1 diabetes. Eur J Endocrinol 2003;148:245-51.
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