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Know Your Blood Parameter: Thyroxine (T4)

Updated: Jul 11

  1. Parameter Name 

    Total T4 (Thyroxine)


  2. Test Type 

    Blood


  3. Normal Range 

    5.0 – 12.0 µg/dL


  4. High Levels Indicate 

    Hyperthyroidism, Graves’ disease, thyroid inflammation, pregnancy (transient).


  5. Low Levels Indicate 

    Hypothyroidism, pituitary disease, iodine deficiency.


  6. Why It's Tested 

    To assess overall thyroid hormone levels in suspected thyroid dysfunction.


  7. Associated Symptoms (if abnormal) 

    High: Weight loss, tremors, heat intolerance 

    Low: Constipation, fatigue, depression


  8. What To Do If Abnormal 

    Check with TSH and Free T4; initiate treatment if clinically indicated.


  9. Common Conditions Related 

    Hypothyroidism, hyperthyroidism, thyroiditis


  10. Nutrition or Lifestyle Connection 

    Balanced iodine intake; selenium and zinc support thyroid hormone conversion.


  11. References (APA Format)

    • MedlinePlus. (2023). T4 test.

    • Mayo Clinic. (2022). Thyroid tests.

    • NIH Office of Dietary Supplements (2023). Iodine.


 
 
 

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