Thyroid Function in Adults with Down's Syndrome

Abstract

The thyroid status of 82 institutionalized adults with Down's syndrome has been assessed. Compared to age and sex matched control subjects, these patients had significantly lower mean total serum thyroxine (T4) and triiodothyronine (T3) concentrations (T4; 69.1+/-22.2 nmol/1; (mean+/-SD) vs. 100.1+/-19.1, P less than 0.001; T13; 1.61+/-0.47 nmol/1 vs. 1.76+/-0.34, P less than 0.025), lower free thyroxine index (FTI), (FTI; 66.1+/-22.4 vs. 95.1+/-20.2, P less than 0.001), and higher basal serum thyrotrophin (TSH) concentrations (TSH; 7.6+/-10.7 mU/1 vs. 3.8+/-1.5, P less than 0.001). These changes were not related to age or sex. Abnormalities in one or more test of thyroid function were demonstrated in at least 38 (46%) of the 82 patients. Two main patterns of abnormality were defined: 1) subnormal T4, FTI and elevated basal TSH levels (primary hypothyroidism) in 13 (16%). All seven of the 13 patients in whom TRH tests were performed showed the expected exaggerated TSH response, and seven out of the 13 patients (54%) had positive thyroid antibodies, 2) Subnormal T4, subnormal or low normal FTI, and basal TSH levels within the normal range in 18 (22%). The mean basal TSH concentration was, however, significantly higher than in patients with normal T4 and FTI levels, suggesting a minor degree of thyroid failure. Only two of the 18 patients (11%) had positive thyroid antibodies. Of the 17 patients in the group tested, 13 showed a normal TSH response to TRH, three an exagerrated response (all females), and one had an impaired response. Other patterns of abnormal thyroid function were observed occasionally: one female patient had biochemical T3 toxicosis; another had the biochemical pattern of subclinical hypothyroidism, four patients with normal basal T4, FTI and TSH levels showed an exaggerated TSH response to TRH and one patient had an impaired response. These data indicate that htyroid dysfunction, in particular hypothyroidism, is common in adults with Down's syndrome, though specific tests are usually required to make the diagnosis. The general reduction in thyroid function in Down's syndrome may be due to impaired development of the thyroid gland. However, frank chemical hypothyroidism may occur only when thyroiditis is superimposed on preexisting diminished thyroid reserve.

Hormonal and autonomic responses to autonomic stimulation are altered in young men with Down syndrome

“…If ACTH response was effective after stimulation (+54%, p<0.01), the cortisol gland did not respond by an appropriate cortisol secretion. This observation was exclusive in DS group and could corroborate the cortical gland deficiency proposed by Murdoch et al [29]. Moreover norepinephrine concentrations were higher after immersion in DS, and this effect was not observed in CONT group.…”

“…Because this increase was not accompanied by a cortisol increase, a corticotropic dysfunction should be considered. Murdoch et al [29] have shown a blunted cortisol response to a Synacthen® test in population with DS, suggesting a cortisol deficiency. In our study this phenomenon seemed to be similar.…”

Down Syndrome and Thyroid Disorders: A Review

“…Other abnormalities may suggest the presence of a thyroid disorder; eg, abnormal electrocardiogram consistent with hypothyroidism, (Murdoch, 1977), presence of a goitre (Ruvalcaba, 1969;Hollingworth, 1974), detection of a pericardial effusion (Werder et al, 1993), dementia (Prasher & Krishnan, 1993), detection of alopecia areata (duVivier & Munro, 1975), premature puberty (Maranon et al, 1951).…”

“…Persons with Down syndrome with circulating thyroid autoantibodies may present with hypothyroidism (Baxter et al 1975;Murdoch et al, 1977;Lobo et al, 1980;Dinani & Carpenter, 1990), hyperthyroidism (Aarskog, 1969;Blumberg & Ruskin, 1987) or may be euthyroid (Hollingsworth et al, 1974). Further, not all individuals with clinical thyroid disease have auto-antibodies (Cutler et al, 1986).…”

Down Syndrome with Thyroid Dysfunction Detected by Neonatal Screening for Congenital Hypothyroidism

“…It is well documented that there is a high prevalence of overt or subclinical hypothyroidism in children and adults with DS (1)(2)(3)(4).…”