What is an Underactive Thyroid?

Hypothyroidism (hypothyroidism for short) is a disease caused by decreased metabolism of the body due to reduced synthesis and secretion of thyroid hormones or insufficient physiological effects. According to its cause, it is divided into three types: primary hypothyroidism, secondary hypothyroidism and peripheral hypothyroidism.

Basic Information

nickname

A minus

English name

hypothyroidism

Visiting department

Endocrinology

Common causes

May be caused by iodine deficiency or insufficient thyroid hormone synthesis

Common symptoms

Pale and swollen, indifferent expression, dry and thick skin, etc.

Causes of hypothyroidism

The etiology is more complicated, more common in the primary, followed by the pituitary, others are rare.

Clinical manifestations of hypothyroidism

1. Pale complexion, swollen eyelids and cheeks, indifferent expression, dry, thickened, rough, and desquamated skin, non-sagging edema, hair loss, yellowish hands and feet, weight gain, thick and brittle nails crack.

2. Nervous and mental system: memory loss, mental retardation, drowsiness, slow response, polydipsia, dizziness, headache, tinnitus, deafness, nystagmus, ataxia, sluggish tendon reflexes, prolonged Achilles tendon reflex period, severe cases may be Dementia, stiffness, and even lethargy.

3. Cardiovascular system: bradycardia, reduced cardiac output, low blood pressure, dull heart sounds, enlarged heart, and concurrent coronary heart disease, but angina pectoris and heart failure generally do not occur, sometimes with pericardial effusion and pleural effusion . Severe cases develop myxedema cardiomyopathy.

4. Digestive system: anorexia, bloating, constipation. In severe cases, paralytic intestinal obstruction may occur. Gallbladder contraction weakens and swells. Half of the patients have gastric acid deficiency, which leads to malignant anemia and iron deficiency anemia.

5. Motor system: muscle weakness, pain, stiffness, may be accompanied by joint diseases such as chronic arthritis.

6. Endocrine system: women have more menstrual periods, prolonged illness, amenorrhea, infertility; men are impotence, hyposexuality. A few patients have lactation and secondary pituitary enlargement.

7. In severe cases, stress caused by cold, infection, surgery, anesthesia, or improper application of sedatives can induce myxedema or coma or "hypothyroidism". Manifestations include hypothermia (T <35 ° C), slowed breathing, bradycardia, decreased blood pressure, relaxation of limb muscle strength, weakened or disappeared reflexes, and even coma, shock, and heart and kidney failure.

8. Mind sickness: dull expression, low dumb pronunciation, pale face, edema around the orbit, widening of the distance between the eyes, flattened nose bridge, thick salivation, large tongue extension, short limbs, duck step.

9. Juvenile hypothyroidism: short stature, low intelligence, delayed sexual development.

Hypothyroidism test

Thyroid function test

Serum TT ₄ , TT ₃ , FT ₄ and FT _{3 were} lower than normal values.

2. Serum TSH value

(1) The TSH of primary hypothyroidism is significantly increased with the decrease of free T4. The subclinical hypothyroidism serum TT ₄ and TT ₃ values are normal, while the serum TSH is slightly elevated. After the TRH stimulant test, the serum TSH level is higher than that of normal people.

(2) Hypophyseal hypothyroidism Serum TSH levels are low or normal or higher than normal, and have no response to the TRH excitation test. After TSH application, serum TT ₄ levels increased.

(3) Hypothalamic hypothyroidism Serum TSH levels are low or normal, and respond well to the TRH excitation test.

(4) Peripheral hypothyroidism (thyroid hormone resistance syndrome) has elevated TSH in central resistance, low TSH in surrounding tissue resistance, and different manifestations in TSH in systemic resistance.

3.X-ray inspection

Enlarged heart, slowed heart rate, pericardial effusion, and plain radiograph of the skull showed that the saddle could be enlarged.

4. ECG examination

Shows low voltage, QT interval prolonged, ST-T abnormal. Echocardiography shows myocardial thickening and pericardial effusion.

5. Lipid, creatine phosphokinase activity increased, glucose tolerance curve was low.

Diagnosis of hypothyroidism

Diagnosis can be made based on the etiology and clinical manifestations of thyroid function.

Differential diagnosis of hypothyroidism

It should be distinguished from renal edema, anemia, and congestive heart failure. According to rT ₃ and the patient's primary disease manifestation, it should be distinguished from low T ₃ syndrome. The symptoms of hypothyroidism and galactorrhea should be distinguished from prolactinoma.

Hypothyroidism treatment

1. Lifetime replacement therapy for thyroid preparations

Early mild cases were dominated by oral thyroid tablets or levothyroxine. Test thyroid function and maintain TSH within normal range.

Symptomatic treatment

In addition to oral thyroid tablets or levothyroxine, intermediate and advanced severe cases require symptomatic treatments such as oxygenation, infusion, infection control, and heart failure. For the treatment of hyperthyroid patients to prevent excessive hypothyroidism.