The thyroid gland produces two related hormones, thyroxine (T4) and triiodothyronine (T3). Hypothyroidism (underactive thyroid) is a condition in which your thyroid gland doesn’t produce enough of certain crucial hormones.
Deficient thyroid hormone secretion can be due to thyroid failure.
Deficient thyroid hormone secretion can be due to pituitary or hypothalamic disease.
It occur in silent or subacute thyroiditis.
Subclinical (Or Mild) Hypothyroidism
It is a state of normal free thyroid hormone levels and mild elevation of TSH.
Clinical (Or Overt) Hypothyroidism
With higher TSH levels and low free T4 levels, symptoms become more readily apparent.
Causes of Hypothyroidism
- Iodine deficiency- Too little iodine can lead to hypothyroidism, and too much iodine can worsen hypothyroidism in people who already have the condition.
- Autoimmune hypothyroidism- Autoimmune disorders occur when your immune system produces antibodies that attack your own tissues. (Hashimoto’s thyroiditis, atrophic thyroiditis )
- Iatrogenic: 131I treatment, subtotal or total thyroidectomy( Removing all or a large portion of your thyroid gland can diminish or halt hormone production.), external irradiation of neck for lymphoma or cancer
- Drugs: iodine excess (including iodine-containing contrast media and amiodarone), lithium, antithyroid drugs, p-aminosalicylic acid, interferon α and other cytokines
- Congenital hypothyroidism: absent or ectopic thyroid gland, dyshormonogenesis, TSH-R mutation
- Infiltrative disorders: amyloidosis, sarcoidosis, hemochromatosis, scleroderma, cystinosis, Riedel’s thyroiditis
- Some women develop hypothyroidism during or after pregnancy (postpartum hypothyroidism), often because they produce antibodies to their own thyroid gland. Left untreated, hypothyroidism increases the risk of miscarriage, premature delivery and preeclampsia — a condition that causes a significant rise in a woman’s blood pressure during the last three months of pregnancy. It can also seriously affect the developing fetus.
- Silent thyroiditis, including postpartum thyroiditis
- Subacute thyroiditis
- After 131I treatment or subtotal thyroidectomy for Graves’ disease
- Hypopituitarism: tumors, pituitary surgery or irradiation, infiltrative disorders, Sheehan’s syndrome, trauma, genetic forms of combined pituitary hormone deficiencies
- Isolated TSH deficiency or inactivity
- Bexarotene treatment
- Hypothalamic disease: tumors, trauma, infiltrative disorders, idiopathic.
Are a woman
Are older than 60
Have a family history of thyroid disease
Have an autoimmune disease, such as type 1 diabetes or celiac disease
Have been treated with radioactive iodine or anti-thyroid medications
Received radiation to your neck or upper chest
Have had thyroid surgery (partial thyroidectomy)
Have been pregnant or delivered a baby within the past six months.
- Dry skin
- Feeling cold
- Hair loss
- Difficulty concentrating and poor memory
- Weight gain with poor appetite
- Hoarse voice
- Menorrhagia (later oligomenorrhea or amenorrhea)
- Impaired hearing
- Dry coarse skin; cool peripheral extremities
- Puffy face, hands, and feet (myxedema)
- Diffuse alopecia
- Peripheral edema
- Delayed tendon reflex relaxation
- Carpal tunnel syndrome
Goiter. Constant stimulation of your thyroid to release more hormones may cause the gland to become larger — a condition known as a goiter.
Heart problems. Hypothyroidism may also be associated with an increased risk of heart disease and heart failure, primarily because high levels of low-density lipoprotein (LDL) cholesterol
Mental health issues. Depression may occur early in hypothyroidism
Peripheral neuropathy. Long-term uncontrolled hypothyroidism can cause damage to your peripheral nerves. These are the nerves that carry information from your brain and spinal cord to the rest of your body — for example, your arms and legs. Peripheral neuropathy may cause pain, numbness and tingling in affected areas.
Infertility. Low levels of thyroid hormone can interfere with ovulation, which impairs fertility.
Birth defects. Babies born to women with untreated thyroid disease may have a higher risk of birth defects compared to babies born to healthy mothers. These children are also more prone to serious intellectual and developmental problems.
- Thyroid profile T,T4,TSH,Anti-TPO antibodies, anti-thyroglobulin (Tg).
- Lipid profile
- Ultrasound thyroid gland