Total T4 (Thyroxine)
Sample Required:
Sample Type: Serum (red Top) or Heparin (Green Top)
Preferred Volume: 1ml whole blood, 0.5ml serum/plasma
Test Code: BBT4
Sample Handling:
-If the sample cannot be analysed within 24 hours of collection, then it must be refrigerated and remain chilled for transport. Please do not freeze unseparated samples.
-Stable in serum or heparinized plasma for 7 days at 2 - 8 oC.
Indications:
Total T4 is assessed in the evaluation of hyperthyroidism and hypothyroidism, and for monitoring patients receiving medication to treat hyperthyroidism and hypothyroidism.
Method:
Electrochemiluminescence immunoassay.
Background:
Hypothyroidism can be congenital or, more frequently, acquired and is a relatively common endocrinopathy of dogs, but is rare in cats. It is most commonly associated with destruction or atrophy of the thyroid gland.
Hyperthyroidism is commonly seen in elderly cats, but is a rare condition in dogs. In cats it is most commonly associated with adenomatous hyperplasia of the thyroid gland; in dogs it can occasionally be seen with a functional thyroid neoplasm.
References:
Reviewed: 18 June 2025.