Download subclinical hypothyroidism

thyroiditis
Dr.m.ghasemi
Ped endocrinologist
Kermanshah university of medical sciences
LYMPHOCYTIC THYROIOITIS (HASHIMOTO THYROIDITIS,
AUTOIMMUNE THYROIDITIS)
• the most common cause of thyroid disease in children and
adolescents
• formerly designated "adolescent" or "simple“ goiter.
• also the most common cause of acquired hypothyroidism,
with or without goiter.
• 1-2% of younger school-aged children
• and 4-6% of adolescents
• have positive antithyroid antibodies as evidence of
autoimmune thyroid disease.
Etiology
• lymphocytic infiltration of the thyroid
• About 60% of infiltrating lymphoid cells are T cells and about 30% express
B-cell markers
• Thyroid antiperoxidase antibodies (TPOAbs; formerly called
antimicrosomal antibodies) and antithyroglobulin antibodies are
demonstrable in the sera of 90% of children with lymphocytic thyroiditis
and in many patients with Graves disease.
• Thyrotropin receptor-blocking antibodies are often present, especially in
patients with hypothyroidism,
• Antibodies to pendrin, in 80% of children with autoimmune thyroiditis.
Clinical Manifestations
2-4 times more common in girls than in boys
• It can occur during the first 3 yr of life but becomes
sharply more common after 6 yr of age and reaches a
peak incidence during adolescence.
• The most common clinical manifestations are goiter
and growth retardation.
• The goiter can appear insidiously and may be small or
large.
• In most patients, the thyroid is diffusely
enlarged, firm, and nontender.
• In about 30% of patients, the gland is lobular and
nodular.
• Most of the affected children are clinically
euthyroid and asymptomatic; some may have
symptoms of pressure in the neck, including
difficulty swallowing and shortness of breath
• Some children have clinical signs of
hypothyroidism, but others who appear clinically
euthyroid have laboratory evidence of
hypothyroidism.
• A few children have manifestations suggesting
hyperthyroidism, but results of laboratory studies
are not necessarily those of hyperthyroidism.
• Occasionally, the disorder coexists with Graves
disease.
• The goiter might become smaller or might
disappear spontaneously,
• or it might persist unchanged for years while
the patient remains euthyroid.
• Most children who are euthyroid at
presentation remain euthyroid.
• In children who initially have mild or subclinical
hypothyroidism, over several years:
• about 50% revert to euthyroidism,
• about 50% continue to have subclinical hypothyroidism,
and a few develop overt hypothyroidism.
• Thyroiditis is the cause of most cases of nongoitrous
(atrophic) hypothyroidism.
• incidence in siblings or parents of affected children may be
as high as 25%.
• The disorder has been associated with many other autoimmune
disorders.
• Autoimmune thyroiditis occurs in 10% of patients with type I
autoimmune polyglandular syndrome (APS- 1), characterized by
autoimmune polyendocrinopathy,
• candidiasis, and
• ectodermal dysplasia (APCED).
• APS-1(HAM syndrome) consists of 2 of the triad of
• hypoparathyroidism,
• Addison disease
• mucocutaneous candidiasis
• APS-1 is autosomal recessive Caused by mutations in the
autoimmune regulatory (AIRE) gene
• Autoimmune thyroiditis occurs in 70% of patients with APS-2
(Schmidt syndrome).
• APS-2 consists of the association of
• Addison disease with
• type 1 diabetes mellitus (TIDM)
• or autoimmune thyroid disease.
• The etiology is unknown, and it typically occurs in early adulthood.
• Autoimmune thyroid disease also tends to be
associated with pernicious anemia, vitiligo, or
alopecia.
• TPOAbs are found in approximately 20% of white
and 4% of black children with TIDM.
• Autoimmune thyroid disease has an increased
incidence in children with congenital rubella.
• Lymphocytic thyroiditis is also associated with
Turner syndrome and Down syndrome.
• In children with Down syndrome
• one study reported that
• 28% had antithyroid antibodies (predominantly
anti-TPOs),
• 7% had subclinical hypothyroidism,
• 7% had overt hypothyroidism,and
• 5% had hyperthyroidism.
• In a study of girls with Turner syndrome:
• 41% had antithyroid antibodies (again,
predominantly anti-TPOs),
• 18% had goiter
• 8% had subclinical or overt hypothyroidism.
Laboratory Findings
• Thyroid function tests (free T4 and TSH) are often
normal,
• although the level of TSH may be slightly or even
moderately elevated in some patients, termed
subclinical hypothyroidism
• goiter may be caused by the lymphocytic
infiltrations or by thyroid growth-stimulating
immunoglobulins.
• Young children with lymphocytic thyroiditis have
serum antibody titers to TPO, but the TG test for
thyroid antibodies is positive in <50%.
• Antibodies to TPO and TG are found equally in
adolescents with lymphocytic thyroiditis.
• When both tests are used, approximately 95% of
patients with thyroid autoimmunity are detected.
• Thyroid scans and ultrasonography usually are not needed.
• thyroid scans reveal irregular and patchy distribution of the
radioisotope,
• and in about 60% or more, the administration of perchlorate results
in a >10% discharge of iodide from the thyroid gland.
•
Thyroid ultrasonography shows scattered hypoechogenicity in most
patients.
• The definitive diagnosis can be established by biopsy of the thyroid;
this procedure is rarely clinically indicated.
Treatment
• If there is evidence of hypothyroidism (overt or
subclinical),replacement treatment with levothyroxine (at
doses specific for size and age) is indicated.
• The goiter usually shows some decrease in size but can
persist for years.
• In a euthyroid patient, treatment with suppressive doses of
levothyroxine is unlikely to lead to a significant decrease in
size of the goiter.
• Antibody levels fluctuate in both treated and untreated
patients and persist for years.
• Because the disease is self-limited in some
instances, the need for continued therapy
requires periodic reevaluation.
• Untreated patients should also be checked
periodically.
• prefer to treat Children with subclinical
hypotyroidism until growth and puberty are
complete, and then reevaluate their thyroid
function
• Prominent nodules, i.e. >1.0 cm, that persist
despite suppressive therapy should be
examined histologically using FNA,
• because thyroid carcinoma or lymphoma has
occurred in patients with lymphocytic
thyroiditis