Types

• Thyroxine (T4) is one of the two major hormones produced by the Thyroid Gland. Almost all of the T4 found in the blood is bound to protein, the rest is free (Unbound) and is the biologically active form of the hormone. Most of the hormones produced by the Thyroid is T4. It is relatively Inactive, but it is converted into much more active T3...

Description

• 4.5-12 ug/dl

Paediatric normal range- 

• 1-3 days- 11.8-22.6 ug/dl
• 1-4 months-7-2-14.4 ug/dl

When to get Tested

• When there are s/s of Hyperthyroidism (Increased heart rate, Anxiety, weight loss, difficulty sleeping, tremors in the hands, weakness, Menstrual irregularity

Elevated Level

• Hyperthyroid states
• Grave’s disease
• Toxic multinodular goiter
• Sub-acute or chronic thyroiditis
• Early Hashimoto’s disease
• Iodine-induced hyperthyroidism
• Germ cell tumours
• Trophoblastic disease

Decreased Level

• Hypothyroidism (including later stage of Hashimoto’s disease, cretinism, myxedema, goitrous disease, following radio iodine or thyroid ablation, infiltrative diseases such as scleroderma, amyloid goiter)
• TBG deficiency
• Excessively treated Hyperthyroidism
• Inadequately treated hypothyroidism
• Malnutrition
• Systemic illness
• Fasting