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Disorder of Thyroid Gland

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Disorder of Thyroid Gland Differential Diagnosis ~9301125 References Harrison s internal medicine Lange Pathophysiology Washington Manual ... – PowerPoint PPT presentation

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Title: Disorder of Thyroid Gland


1
Disorder of Thyroid Gland
  • Differential Diagnosis

9301125???
2
References
  • Harrisons internal medicine
  • Lange Pathophysiology
  • Washington Manual
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3
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  • Stage of goiter
  • Stage 0 no goiter
  • Stage Ia goiter detectable only by palpation
    and not visible when the neck is fully extended
  • Stage Ib goiter palpable and visible only when
    the neck is fully extended
  • Stage II goiter visible with the neck in normal
    position
  • Stage III very large goiter that can be
    recognized at a considerable distance.

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4
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5
Overview of Thyroid Disease
  • The clinician commonly encounters patients with
    one of five types of thyroid dysfunction
  • (1) hyperthyroidism (thyrotoxicosis), caused by
    an excess of thyroid hormones
  • (2) hypothyroidism (myxedema), caused by a
    deficiency of thyroid hormones
  • (3) goiter, a diffuse enlargement of the thyroid
    gland, caused by prolonged elevation of TSH
  • (4) thyroid nodule, a focal enlargement of a
    portion of the gland, caused by a benign or
    malignant neoplasm and
  • (5) abnormal thyroid function tests in a
    clinically euthyroid patient.

6
Pathogenesis of Thyroid Disorder
  • Autoimmune processes
  • stimulate the overproduction of thyroid hormones
    (thyrotoxicosis) or
  • cause glandular destruction and hormone
    deficiency (hypothyroidism).
  • benign nodules and various forms of thyroid
    cancer

7
Pathogenesis-autoimmune process
  • sensitization of the host's own lymphocytes to
    various thyroidal antigens.
  • Three major thyroidal antigens have been
    documented
  • thyroglobulin (Tg),
  • thyroidal peroxidase (TPO),
  • TSH receptor.
  • ExampleIn Graves' disease, the TSH receptor
    autoantibody TSH-R stim Ab stimulates the
    thyroid follicular cells to produce excessive
    amounts of T4 and T3.

8
Antibody? Adenoma? Ectopic Secretion?
9
Autoimmune thyroiditis
  • Hashimotos thyroiditis
  • marked lymphocytic infiltration of the thyroid
    with germinal center formation
  • atrophy of the thyroid follicles accompanied by
    oxyphil metaplasia, absence of colloid, mild to
    moderate fibrosis.
  • Atrophic thyroiditis
  • the fibrosis is much more extensive,
  • lymphocyte infiltration is less pronounced,
  • thyroid follicles are almost completely absent.
  • Atrophic thyroiditis likely represents the end
    stage of Hashimoto's thyroiditis rather than a
    distinct disorder.

10
Terminology
  • Thyrotoxicosis the state of thyroid hormone
    excess
  • Hyperthyroidism the result of excessive thyroid
    function.
  • However, the major etiologies of thyrotoxicosis
    are hyperthyroidism caused by Graves' disease,
    toxic multinodular goiter, and toxic adenomas.

11
Thyroid function tests
  • Thyroid function tests
  • TSH T3 T4 RT3U FTI
    Free T4
  • Antimicrosome AB (Anti-peroxidase AB) (TPO AB)
  • Antithyroglobulin AB
  • TSH receptor AB
  • thyroglobulin

12
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  • Best initial diagnostic test Plasma TSH
  • Free T4 and Free T3 p.s.T3(total T3?total
    T4??????ex.drug estrogen??? )
  • Autoantibodies
  • Anti-thyroglobulin antibodies
  • Antithyroid microsomal/thyroid peroxidase
    antibodies(TPO)
  • ????--??????Hashimotos thyroiditis
    ????---??????????????
  • TSH receptor Ab -Graves disease?specific?Ab

13
Lab testHyperthyroidism
  • Serum thyroid hormones are elevated.
  • Both the free thyroxine (FT4) and the free
    thyroxine index (FT4I) are elevated.
  • In 510 of patients, T4 secretion is normal
    while T3 levels are high (so-called T3 toxicosis
  • Hyperthyroidism resulting from Graves' disease
    suppressed serum TSH level
  • However, TSH levels may also be suppressed in
    some acute psychiatric and other nonthyroidal
    illnesses.
  • In the rare TSH-secreting pituitary adenomas
    (so-called secondary hyperthyroidism) and in
    hypothalamic disease with excessive TRH
    production (so-called tertiary hyperthyroidism),
    hyperthyroidism is accompanied by elevated plasma
    TSH.
  • The radioactive iodine (RAI) uptake of the
    thyroid gland at 4, 6, or 24 h
  • increased when the gland produces an excess of
    hormone (eg, Graves' disease)
  • decreased when the gland is leaking stored
    hormone (eg, thyroiditis),
  • when hormone is produced elsewhere (eg, struma
    ovarii), and when excessive exogenous thyroid
    hormone is being ingested (eg, factitious
    hyperthyroidism). Technetium 99m scanning can
    provide information similar to that obtained with
    RAI and is quicker and entails less radiation
    exposure.
  • The TRH test is sometimes helpful in diagnosis
    when patients have confusing results of thyroid
    function tests. In normal individuals,
    administration of TRH (500 g intravenously)
    produces an increase in serum TSH of at least 6
    mU/L within 1530 min. In primary
    hyperthyroidism, TSH levels are low and TRH
    administration induces little or no rise in the
    TSH level.

14
Flow chart of Hyperthyroidism D.D.
15
Flow chart of Hypothyroidism D.D.
16
Features of Graves Disease
  • 6080 of thyrotoxicosis, women predominate,
    2050 y/o
  • Ophthalmopathy / Proptosis (06)
  • Pretibial myxedema

17
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