Hyperthyroidism

• Disorders such as Graves’ disease (an autoimmune condition) cause an overproduction of thyroid hormones.

Thyroid Hormone Overdose

• Excessive intake of thyroid hormones (whether through treatment or accidental ingestion) results in increased FT4 levels.

Thyroiditis

• In certain inflammatory thyroid conditions, damaged follicles may temporarily “leak” hormones into the circulation.

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Hypothyroidism

• Often due to autoimmune destruction (Hashimoto’s thyroiditis) or iodine deficiency, leading to insufficient hormone production.

Central Hypothyroidism

• Pituitary or hypothalamic dysfunction can result in low stimulation of the thyroid.

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Children/Infants

• Adequate FT4 is vital for brain development.
• Deviations can affect growth and neurodevelopment.

Elderly

• Mild variations may occur.
• Chronic low levels can contribute to fatigue, weight gain, or depression.

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Thyroid Function

• Common Thyroxine (T4), Free Thyroxine (FT4), Free Triiodothyronine (FT3):
  These markers measure the overall thyroid hormone production and the bioavailable (active) fractions. While Common T4 reflects total hormone levels (both bound and free), FT4 and FT3 specifically indicate the unbound, active hormones that drive metabolic processes.
  
  
• Thyrotropic Hormone (TSH):
  This pituitary hormone regulates thyroid hormone synthesis through a negative feedback mechanism. Elevated or suppressed TSH levels provide insight into thyroid function and help direct further evaluation of thyroid disorders.
  
  
• Thyroxine Binding Globulin (TBG):
  TBG is the main protein binding thyroid hormones in the blood. It influences the proportion of hormone that remains free versus bound, affecting the interpretation of Common T4 compared to FT4 and FT3 levels.
  
  
• thyreoglobulin;calcitonin; tumerous marker thyreoglobulin:
  These markers focus on thyroid tissue activity and neoplastic surveillance.
  
  
  
  • thyreoglobulin reflects the functional activity of thyroid follicular cells.
  • When used as a tumour marker (tumerous marker thyreoglobulin), it helps monitor for residual or recurrent differentiated thyroid cancer following treatment.
  • calcitonin, secreted by the thyroid’s C cells, is particularly valuable in detecting medullary thyroid carcinoma.

Together, these markers offer a comprehensive view of thyroid gland function, regulation, and tissue integrity, integrating hormonal activity with diagnostic tools for thyroid cancer surveillance.

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