The relationship of juvenile hypothyroidism to chronic lymphocytic thyroiditis

Hashimoto's thyroiditis in children and adolescents: a retrospective study on clinical, epidemiological and laboratory properties of the disease

Hashimoto's thyroiditis (HT) is the most common cause of goiter and acquired hypothyroidism in children and adolescents in iodine replete areas. To find out the clinical, epidemiological and laboratory characteristics of the disease in childhood, we reviewed files of 162 children and adolescents with HT followed in the Department of Pediatric Endocrinology, Hacettepe University Faculty of Medicine.

RESULTS

Female patients constituted 86.4% (n = 140) of all patients with a female:male ratio of 6.4. Mean age at diagnosis was 11.4 +/- 2.97 years (age range 4.4-16.5 years). At the time of diagnosis 43.2% of the patients (n = 70) were euthyroid, 24.1% (n = 39) had subclinical hypothyroidism, 21% (n = 34) had overt hypothyroidism, and 8.6% (n = 14) had overt and 3.1% (n = 5) subclinical hyperthyroidism.

CONCLUSIONS

Autoimmune thyroiditis is more frequent in females, and increases in frequency over age during childhood and adolescence. At the time of diagnosis, frequency of overt and subclinical hypothyroidism is similar to that of euthyroid goiter.

Juvenile autoimmune thyroiditis

Autoimmune thyroiditis is a frequent cause of goiter in children and studies point to the increasing prevalence of juvenile autoimmune thyroiditis (JAT) in children and adolescents. Clinically, JAT can manifest, depending on the presence or absence of goiter, as either a goitrous form or atrophic form. Both are characterized by the presence of thyroid antibodies in serum, with the goitrous form being more common in children. Recent evidence suggests that thyroid autoimmunity originates from an interaction of genetic, endogenous and environmental factors which end up activating thyroid-specific autoreactive T-cells in susceptible children. In addition to underlying genetic/HLA predisposition, factors including sex hormones, glucocorticoids, low birth weight, radiation and drugs may play a role in thyroid autoimmunity. Patients with JAT can present due to thyroid enlargement or symptoms arising due to hypothyroidism. Asymptomatic enlargement of the thyroid gland is a common presenting complaint, especially in older children and adolescents. Thyroid function can vary from euthyroidism to subclinical or overt forms of hypothyroidism and less commonly hyperthyroidism. Accordingly, patients can be symptomatic. There is considerable debate regarding the management of patients with euthyroidism or subclinical hypothyroidism. Available evidence indicates the presence of residual goiter in endemic form and a high prevalence of JAT in children. It is suggested that children should be screened for goiter as part of school health examinations, and goitrous children should be monitored for thyroid function.

A boy with atrophic thyroiditis of prepubertal onset, who was positive for TSH-binding inhibitor immunoglobulins

A 12 year old boy was admitted to our hospital because of short stature. From the age of 7, his growth velocity decreased and he manifested intolerance to low temperatures, hoarseness, dry skin, and slowness of thought and physical movement. On admission, his height was 129.8 cm (-3 s.d.) and his body weight was 43.2 kg (-0.5 s.d.). His clinical features also included relaxation phase of tendon reflexes, periorbital puffiness and cold skin but no struma. His bone age was 9 years. His serum thyroxine (T4), triiodothyronine (T3), free T4 and free T3 were low, while his thyrotropin was high. He was positive for antithyroglobulin antibodies, antimicrosomal antibodies, and TSH-binding inhibitor immunoglobulins. He was diagnosed as having atrophic thyroiditis. We also determined the HLA haplotypes of his family members. His father's HLA haplotypes were A2, BW61(a) and A24, BW52(b), while his mother's haplotypes were A24, BW52(c) and A30, BW60(d). The HLA haplotypes of both the patient and his younger brother showed a and d, while the patient's elder brother's HLA haplotypes showed b and c. His family members all had normal thyroid function, but his father was positive for antimicrosomal antibodies. In summary, we describe a rare case where the onset of hypothyroidism was prepubertal, where the pathogenesis may have involved TSH-receptor blocking antibodies, and where the inheritance of the disease may have been from the paternal side of the family.

Macroorchidism and testicular fibrosis associated with autoimmune thyroiditis

A 16-year-old male with long-standing atrophic chronic lymphocytic thyroiditis was evaluated for macroorchidism. A testicular biopsy prior to treatment revealed peritubular and interstitial fibrosis, reduced spermatogenesis and sparse Leydig cells with nonprominent smooth endoplasmic reticulum. Biological/immunological LH and FSH ratios were reduced, I-LH and FSH response to GnRH was blunted, and levels of testosterone and androstenedione were low. Twenty-two months after thyroid treatment, the testicular size was unchanged, and the degree of fibrosis showed minimal regression. Spermatogenesis with normal morphology was present, Leydig cells with Reinke crystals were present, and surface area and diameter of the seminiferous tubules had increased only slightly. There was a normal I-LH and FSH response to GnRH, and normal levels of testosterone and androstenedione. This study, along with previous reports, suggests that the etiology of the hypothyroid state may influence the development of testicular fibrosis.

Comparison of atrophic and goitrous auto-immune thyroiditis in children: clinical, laboratory and TSH-receptor antibody studies

We studied the clinical features, laboratory and thyroid functions and thyrotropin (TSH)-receptor and thyroid-stimulation antibodies in 21 patients with atrophic auto-immune thyroiditis (AAT) and 48 patients with goitrous auto-immune thyroiditis (GAT) of childhood onset. The clinical features of patient with AAT were cessation of growth and obesity, while asymptomatic enlargement of the thyroid gland was the sole symptom in most patients with GAT. Although the ages at diagnosis were comparable in both groups, the estimated ages at onset were much lower in patients with AAT than in those with GAT. Patients with AAT exhibited more severe hypothyroidism when evaluated by serum thyroxine (T4), tri-iodothyronine (T3), TSH, cholesterol levels and basal metabolic rates. The 24 h 123I-thyroidal uptake was significantly lower in patients with AAT than in those with GAT. None of the 19 patients with AAT possessed TSH-binding inhibitor immunoglobulins (TBII). On the other hand, 3 of the 32 GAT patients tested, possessed weak to potent TBII activities. Three TBII-positive patients with GAT also possessed thyroid-stimulation blocking antibodies. These findings suggest that: 1. Pathogenesis of AAT in children whose onset of hypothyroidism was before puberty is not due to TSH-receptor blocking antibodies, which are often found in patients with AAT of postpubertal onset. 2. AAT in children is considered not to be due to the later stage of GAT. 3. Some patients with GAT possessed TSH-receptor blocking antibodies. The aetiology and pathogenesis of AAT in children have yet to be elucidated.

Long-term growth in juvenile acquired hypothyroidism: the failure to achieve normal adult stature

It has been suggested that complete catch-up growth is achieved with treatment in patients with juvenile acquired hypothyroidism. We tested this assumption by examining long-term growth in 18 girls (mean [+/- SD] age, 11.4 +/- 2.7 years; bone age, 6.2 +/- 3.1 years) and 6 boys (age, 10.6 +/- 4.7 years; bone age, 6.4 +/- 2.7 years) with severe primary hypothyroidism (serum thyroxine level 1.1 +/- 0.3 micrograms per deciliter [13 +/- 4 nmol per liter]). At diagnosis, heights were 4.04 +/- 0.5 and 3.15 +/- 0.4 SD below the mean heights for age of normal girls and boys, respectively. The patients were treated with levothyroxine (3.4 +/- 0.3 micrograms per kilogram of body weight per day) to maintain normal thyroid function. During the first 18 months of therapy, the children's skeletal maturation exceeded the maturation expected for their statural growth, regardless of whether or not they were undergoing pubertal development. Predictions of decreased adult height were based on these observations. At maturity, girls and boys stood approximately 2 SD below normal adult stature, at 149 +/- 5.0 cm and 168 +/- 5.1 cm, respectively. Heights at maturity were also lower than midparental heights (P less than 0.01) and lower than pre-illness standard-deviation scores for height (P less than 0.01). The deficit in adult stature was significantly related to the duration of hypothyroidism before treatment (P less than 0.01). We conclude that despite treatment, prolonged juvenile acquired hypothyroidism results in a permanent height deficit related to the duration of thyroxine deficiency before treatment.

Natural course of juvenile autoimmune thyroiditis

Forty-six patients with juvenile autoimmune thyroiditis were followed for an average of 6.5 years. The diagnosis was based on a firm goiter and on cytologic findings of lymphocytic thyroiditis. The thyroid function and the size of the thyroid gland were regularly evaluated, and thyroid cytologic findings reevaluated once about 4.5 years after the diagnosis was made. Initially, 24 patients were euthyroid, 16 subclinically hypothyroid, and six hypothyroid. At the end of follow-up, 29 patients were euthyroid, six subclinically hypothyroid, and 11 hypothyroid, but there had been an extensive exchange of individual patients among these three groups. At cytologic reevaluation, the changes were virtually unaltered. Thyroid antibodies and circulating immune complexes were repeatedly tested: on one or more occasions, 85% of the patients had positive test results for thyroid antibodies, and about 50% for circulating immune complexes. Hypothyroidism at the end of follow-up correlated with the initial hypothyroid state and with thyroglobulin antibodies of IgG class detected by enzyme immunoassay. The best predictors of the final hypothyroid state were female sex, initial hypothyroidism, IgG thyroglobulin antibodies by EIA, and IgG circulating immune complexes assayed by conglutinin-binding test-EIA.

Acute hypothyroidism in a 3 year old

A 3 year old girl presented with a three week history of lethargy, constipation, and joint swelling. Investigation showed primary hypothyroidism associated with immunological changes including thyroglobulin antibodies. Reassessment several months after beginning thyroxine treatment confirmed persisting hypothyroidism. Primary hypothyroidism may present as a rapid onset disorder.

Organ-specific autoantibodies in children with common endocrine diseases

Sera from 438 children were examined for autoantibodies to thyroid microsomes, thyroglobulin, pancreatic islet cells, gastric parietal cells, and adrenocortical cells by indirect hemagglutination and immunofluorescence techniques. A modification of the indirect hemagglutination technique allowed specific detection of low titers of antithyroidal antibodies. The subjects included a control group (117) with no known autoimmune disease, and children with disorders of the thyroid (88), insulin-dependent diabetes mellitus (201), Turner's Syndrome (24), and Addison disease (8). A subject's age at the time of disease onset and the race and sex were correlated with the prevalence of autoantibodies. The coincidence of autoantibodies to components of the thyroid with autoantibodies to gastric parietal cells was increased in children with disorders of the thyroid (94%, 18/19) over that observed in diabetes (29%, 4/14), Turner syndrome (0%), or Addison disease (0%), perhaps indicating different genetic propensities for the development of parietal cell antibodies in these groups. Islet cell antibodies were not found in subjects with Turner syndrome, nor were they more prevalent in white or black subjects with diabetes. The incidence of organ-specific autoantibodies in individuals without overt clinical disease may reflect an altered immunologic state that will lead eventually to autoimmune disease. Islet cell antibodies decline in prevalence in diabetes, whereas thyroid antibodies in disorders of the thyroid do not; this may reflect differences in the pathogenesis of these common autoimmune endocrine disorders in children.

Clinical recognition of juvenile hypothyroidism in the early stage

The clinical manifestations of biochemically-confirmed acquired hypothyroidism in nineteen children and adolescents were reviewed to evaluate the symptoms and signs in the early stage of the disease. The group consisted of 14 girls and 5 boys ranging in age from 4 to 15 years. In 13 of the 19 patients with profound biochemical hypothyroidism, classical symptoms were often absent and clinical signs limited. In these patients, hypothyroidism was presumed to have been short in duration and consequence of chronic lymphocytic thyroiditis. In the remaining 6 patients, hypothyroidism was long-standing and clinical presentation classical, including disproportionate weight gain, fatigue, cold intolerance, myxedematous feature, growth retardation and constipation. Goiter was the most consistent finding in both groups and was present in all instances of spontaneously acquired primary hypothyroidism. These observations emphasize the importance of routine examination of the thyroid gland, particularly in preadolescent and adolescent girls. The finding of goiter may be the only detectable sign of hypothyroidism in the early stage of the disease. Biochemical evaluation should not be deferred because of a clinically euthyroid presentation. Replacement therapy must be instituted when findings indicate a hypothyroid state. Failure to recognize and treat hypothyroidism in these pubertal patients may compromise the adult height, since skeletal maturation will proceed under the influence of sex hormones despite the presence of hypothyroidism.

Thyroid antibodies in children and adolescents with thyroid disorders

Thyroid antibodies were determined by three different techniques in the sera of 125 children and adolescents with thyroid disorders and in the sera of 53 short, normal children without thyroid dysfunction. The incidence of antithyroglobulin antibodies in patients with thyroiditis was highest when measured by radioimmunoassay (85%), less than when measured by hemagglutination (24%), and least by antimicrosomal antibodies (7%). No patient who had initially negative serum for RATA subsequently had positive tests during follow-up of five to 24 months, whereas eight of 31 patients with initially negative serum for ATA later developed positive tests. Treatment appeared to have a suppressive effect on RATA, but not on ATA titers, in hypothroid patients with clinical thyroiditis. The incidence of hypothyroidism in the patients with clinical thyroiditis on initial presentation was significant (37%) and suggests that identification of children and adolescents with thyroiditis is important to ensure adequate medical follow-up.

Occurrence and natural history of chronic lymphocytic thyroiditis in childhood

In a six-year survey of 5,179 school children in Arizona, Utah, and Nevada 62 cases of chronic lymphocytic thyroiditis were identified giving a prevalence of 1.2%. Thyroids were enlarged in 85%, firm in 60%, and had an irregular or lobulated surface in 75%. Antibodies to thyroglobulin were demonstrable in the serum at some time during the course of the disease in 76% by the tanned red blood cell technique and in 93% by radioimmunoassay. Serum TSH concentrations were elevated in seven of 15 subjects. Many of the cases were early or mild thyroiditis and, in most instances, subjects were asymptomatic and considered clinically euthyroid. Two subjects were hypothyroid, and two appeared clinically hyperthyroid. Spontaneous resolution of thyroiditis occurred in 15 of 32 individuals who received no treatment. Resolution occurred in 14 of 30 children treated with thyroid hormone supplement. The results suggest that lymphocytic thyroiditis in children may be present without symptoms and in many is a self-limiting disorder from which complete recovery occurs spontaneously.

Autoimmune thyroid disease in children with mongolism

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