Thyroid and Parathyroid

autoimmune thyroiditis is encountered in children but is rare in those under 5 years of
age. In adolescents 40 percent of goiters are from autoimmune thyroiditis. Other
predisposing conditions to autoimmune thyroiditis include Down syndrome, familial
Alzheimer's disease, and Turner's syndrome. It is more common in areas of iodine
excess. Studies suggest that thyroid cells in Hashimoto's thyroiditis have increased
FAS receptors and that interleukin-1 induces abnormal FAS expression and triggers
. apoptosis or increased programmed thyroid cell death
Pathology
In Hashimoto's disease the thyroid gland typically is firm and mildly enlarged. The
enlargement usually is symmetrical. Frequently the pyramidal lobe also is enlarged.
Histologically, there is follicular and Hürthle cell hyperplasia associated with
lymphocytic and plasma cell infiltration and formation of lymphoid follicles. The
disease is usually focal but gradually extends to involve the whole gland. Epithelial
cell degeneration occurs with fragmentation of the basement membrane, and
remaining epithelial cells enlarge and demonstrate oxyphilic changes (Hürthle or
Askanazy cells). As lymphocytic infiltration progresses, the thyroid tissue degenerates
. and may be replaced by fibrous tissue
Clinical Manifestations
Approximately 20 percent of patients with Hashimoto's thyroiditis present with signs
and symptoms of hypothyroidism; a few patients present with hyperthyroidism
(Hashitoxicosis). Most patients are euthyroid when the diagnosis is made. The most
common presenting symptom is a tightness in the throat, often associated with a
painless, nontender enlargement of the thyroid gland. Compression of the trachea or a
recurrent laryngeal nerve is rare. Rapid enlargement of the thyroid gland should raise
suspicion of thyroid lymphoma or carcinoma. Palpation usually demonstrates a
diffusely enlarged, firm, often granular thyroid gland; in some cases the gland also is
nodular. Usually the pyramidal lobe is enlarged. Evidence of other autoimmune
conditions, such as disseminated lupus, rheumatic arthritis, and myasthenia gravis,
. may be present
Diagnostic Findings
In early Hashimoto's thyroiditis, patients may present with a transient rise in serum
thyroid hormone levels, but as the disease progresses, the serum TSH level rises as
serum T4 and T3levels fall. The diagnosis is confirmed by the presence of circulating
antithyroid antibodies. These antibodies are directed against the membrane-bound
enzyme involved in thyroid hormone synthesis, thyroid peroxidase (TPO), formerly
called antimitochondrial antibodies, in almost 100 percent of patients and against
thyroglobulin in about 50 percent of patients. FNAC examination of the thyroid gland
occasionally is useful in confirming the diagnosis of Hashimoto's thyroiditis and in
. patients in whom malignancy is suspected
Treatment
In the absence of compressive symptoms, patients demonstrating goiter, with or
without evidence of hypothyroidism, are best treated with thyroid hormone.
Reduction in thyroid goiter size with thyroxine treatment is variable but is more
commonly seen in younger patients. Surgical intervention is indicated for patients
complaining of obstructive symptoms, for cosmetically unacceptable goiters, or when