Hyperthyroidism

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HYPERTHYROIDISM
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INTRODUCTION

• Hyperthyroidism, also known as Thyrotoxicosis, is
  the clinical syndrome that results from elevated
  concentrations of free thyroid hormone in the
  plasma, associated with clinical evidence of
  hypermetabolism.

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CAUSES
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GRAVES DISEASE (GD)

• GD is overall the most common cause of
  Hyperthyroidism. GD is caused by a generalized
  over activity of the entire thyroid gland
  (Hyperthyroidism).
• GD is an autoimmune disorder in which Thyroid
  Receptor Antibodies (TRAbs) stimulate the TSH
  receptor, increasing thyroid hormone production.

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Prevalance

• Women are more frequently affected by Graves
  Disease than men by a 51 ratio. TRAbs are
  present in 70-100 of Graves Disease (85-100
  for activating antibodies and 75-96 for blocking
  antibodies).
• The prevalence of hyperthyroidism has been
  studied in several studies in India.
• In an epidemiological study from Cochin,
  Subclinical and Overt Hyperthyroidism were
  present in 1.6 and 1.3 of subjects
  participating in a community survey.
• In a hospital-based study of women from
  Pondicherry, Subclinical and Overt
  Hyperthyroidism were present in 0.6 and 1.2 of
  subjects.

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Pathogenesis

• The Hyperthyroidism of Graves Disease is caused
  by Thyroid stimulating immunoglobulin that are
  synthesised in the thyroid gland as well as in
  bone marrow and lymphnodes. A combination of
  environmental and genetic factors, including
  polymorphism in HLA- DR, CTLA-4, CD25, PTPN22
  TSH-R contribute to Graves Disease
  susceptibility. Cytokines appear to play a major
  role in thyroid-associated opthalmopathy.

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Clinical Manifestations
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Laboratory Evaluations

• In Graves Disease, the TSH level is suppressed
  total and unbound thyroid hormone levels are
  increased. In 2-5 of patients, only T3 is
  increased (T3 toxicosis).
•  Measurement of Thyroid receptor antibodies is
  the most reliable diagnostic method if the
  diagnosis is unclear clinically.

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A SCHEME FOR EVALUATING SUSPECTEDHYPERTHYROIDISM
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HYPERTHYROIDISM IN PREGNANCY

• Graves disease is the most common cause of
  autoimmune hyperthyroidism in pregnancy,
  occurring in 0.11 (0.4 clinical and 0.6
  subclinical) of all pregnancies. More frequent
  than Graves disease as the cause of
  thyrotoxicosis is the syndrome of gestational
  hyperthyroidism defined as transient
  hyperthyroidism, limited to the first half of
  pregnancy characterized by elevated FT4 and
  suppressed or undetectable serum TSH, in the
  absence of serum markers of thyroid
  autoimmunity . It is diagnosed in about 13
  of pregnancies, depending on the geographic area
  and is secondary to elevated hCG
  levels. Determination of TSH receptor antibody
  (TRAb) is indicated for differentiating
  gestational hyperthyroidism from Graves
  hyperthyroidism in pregnancy.

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Fetal risks for women with active Graves
hyperthyroidism are

• 1) fetal hyperthyroidism
• 2) neonatal hyperthyroidism
• 3) fetal hypothyroidism
• 4) neonatal hypothyroidism
• 5) central hypothyroidism

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Recommendation

• If the patient has a past or present history of
  Graves disease, a maternal serum determination
  of TRAb should be obtained at 2024 weeks
  gestation for determining the risk of Neonatal
  Thyrotoxicosis.

TEST RANGE AVAILABLE
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CLINICAL REFERENCE

• Harrisons Principles of internal Medicine,
  18th Edition
• Guidelines of the American Thyroid Association
  for the Diagnosis and Management of Thyroid
  disease during Pregnancy Postpartum, 2011
• Tietz Textbook of Clinical Biochemistry, Fifth
  Edition
• For more information about Health Disease visit
  https//www.lalpathlabs.com/
• HYPOTHYROIDISM

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Thank You