Know Your Blood Parameter: Thyroxine (T4)

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.