T3 serum total triiodothyronine, which is a commonly used indicator to determine hyperthyroidism or hypothyroidism, diagnosed as a specific indicator of hyperthyroidism, as well as for the assessment of the severity of the disease, and its application in treatment monitoring. Adults: 1.8 to 2.9 nmol/liter (0.12 to 0.19 ug/di). T4 thyroxine Total serum thyroxine, the body’s primary thyroid, decreases in concentration with age. It is a common indicator for determining hyperthyroidism (commonly known as “no one in sight”) or hypothyroidism (commonly known as “hypothyroidism”), as well as for assessing the severity of the disease and for general treatment monitoring. The following are the clinical significance of T3 and T4.
Clinical significance of TT4 measurement
Measurement methods: RIA, chemiluminescence immunoassay and enzyme-linked immunoassay, etc.
Characteristics: It mainly reflects the level of serum bound T4 (99.98% of TT4). It is sensitive to hypothyroidism and changes in iodine levels in the body.
Normal value: Refer to each laboratory value, age-related.
Elevated: hyperthyroidism, thyroiditis, high TBG, high iodine reserve.
Decreased: hypothyroidism, reduced serum TBG, iodine deficiency, severe liver, kidney and other systemic diseases.
Clinical significance of serum TT3 determination
Measurement methods: RIA, chemiluminescent immunoassay and enzyme-linked immunoassay, etc.
Characteristics: Reflects the level of bound T3 (about 99.7% of TT3) in serum. Sensitive to hyperthyroidism.
Normal values: Refer to various laboratory values, normal levels decrease with age.
Elevated: hyperthyroidism, various types of thyroiditis, elevated serum TBG.
Decreased: primary or secondary hypothyroidism, decreased serum TBG, suppression of T4 to T3 factors (low T3 syndrome).
Clinical significance of serum FT4 determination
Methods: RIA, chemiluminescent immunoassay, enzyme-linked immunoassay, etc.
Characteristics: Not affected by TBG in serum, but some methods are still mildly affected; the level is micro, FT4 is about 0.02% of TT4.
Elevated: hyperthyroidism, thyroiditis and euthyroxine (L-thyroxine) treatment, etc. Pregnancy (certain kits only).
Decrease: Hypothyroidism, severe systemic diseases.
Influencing factors: Some kits are influenced by serum albumin concentration.
Clinical significance of serum FT3 determination
Methods: RIA, chemiluminescent immunoassay, enzyme-linked immunoassay, etc.
Characteristics: Not affected by TBG in serum. However, some methods are still mildly affected; the content is slight, and FT3 accounts for about 0.3% of TT3.
Elevated: hyperthyroidism, various types of thyroiditis, thyroid tablets (containing T3) treatment, etc.
Decrease: primary or secondary hypothyroidism, factors causing low T3 syndrome.
Influencing factors: Some kits are influenced by serum albumin concentration.