Low free T4 causes and symptoms

T4- thyroxine is one of the thyroid hormones that is produced by thyroid gland. There are 2 thyroid hormones as T4-thyroxine and T3-triiodothyronine secreted by thyroid gland.

Thyroid gland is a small, butterfly shaped gland in front of your neck, below the Adam’s apple. Thyroid gland produces thyroid hormones by the effect of TSH- thyroid stimulating hormone. TSH is secreted by pituitary gland and stimulates thyroid gland for thyroid hormone production.

T3 is the more active thyroid hormone and T4 is transformed to T3 for body usage. 1% of the T4 is found free in your body and called free T4 (fT4). Insufficient levels of thyroid hormones are called hypothyroidism- underactive thyroid gland and may cause low free T4. Free T4 level should be evaluated with T3 and TSH levels for diagnosis.

Low free T4 symptoms

free t4

Low free T4 level may cause hypothyroidism and sometimes these type of symptoms may be found;

  • Fatigue
  • Weakness
  • Depression
  • Difficulty concentrating
  • Hair loss
  • Weight gain
  • Dry skin
  • Constipation
  • Menstrual changes
  • Memory impairment
  • Fluid retention
  • Feeling cold
  • Muscle weakness
  • Muscle aches
  • Decreased fertility
  • Decreased sweating
  • Dry mouth

Low free T4 causes

Low T4-thyroxine thyroid hormone may be caused by several reasons like under-active thyroid gland- hypothyroidism

  • Hypothyroidism; under-active thyroid gland
  • Hashimoto’s thyroiditis- an autoimmune disease
  • Iodine deficiency
  • Drugs
  • Radioactive iodine
  • Cushing’s syndrome
  • Cancer
  • Severe illness
  • Thyroid gland surgery-removal
  • Pituitary gland failure; under active pituitary gland
  • Cirrhosis
  • Chronic liver disease
  • Under active hypothalamus
  • Genetic problems
  • Radiation therapy for neck or head cancers
  • Kidney failure
  • Large thyroid – goitrous thyroid
  • Small thyroid- athropic thyroid



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