Know Your Blood Parameter: Thyroxine (T4)
- Zeenat Khalil
- Jun 23
- 1 min read
Updated: Jul 11

Parameter Name
Total T4 (Thyroxine)
Test Type
Blood
Normal Range
5.0 – 12.0 µg/dL
High Levels Indicate
Hyperthyroidism, Graves’ disease, thyroid inflammation, pregnancy (transient).
Low Levels Indicate
Hypothyroidism, pituitary disease, iodine deficiency.
Why It's Tested
To assess overall thyroid hormone levels in suspected thyroid dysfunction.
Associated Symptoms (if abnormal)
High: Weight loss, tremors, heat intolerance
Low: Constipation, fatigue, depression
What To Do If Abnormal
Check with TSH and Free T4; initiate treatment if clinically indicated.
Common Conditions Related
Hypothyroidism, hyperthyroidism, thyroiditis
Nutrition or Lifestyle Connection
Balanced iodine intake; selenium and zinc support thyroid hormone conversion.
References (APA Format)
MedlinePlus. (2023). T4 test.
Mayo Clinic. (2022). Thyroid tests.
NIH Office of Dietary Supplements (2023). Iodine.
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