Geriatric hypothyroidism

Introduction to senile hypothyroidism Hypothyroidism (hypothyroidism) is a systemic disease caused by insufficient synthesis or secretion of thyroid hormones, which can occur at any age. It is not uncommon for the elderly to report to the elderly aged 65 years. The prevalence of clinical hypothyroidism is about 1% to 5%, and 5% to 15% of the population has subclinical hypothyroidism, and its prevalence increases with age, and the prevalence rate among inpatients is higher. . basic knowledge The proportion of illness: the incidence rate of middle-aged and elderly people over 50 years old is about 0.002%--0.004% Susceptible people: good for the elderly over 65 years old Mode of infection: non-infectious Complications: edema, coma, hypotension

Causes of senile hypothyroidism

Causes:

Chronic lymphocytic thyroiditis, also known as Hashimotos thyroiditis, is an autoimmune disease that is the leading cause of hypothyroidism in the elderly. It has normal thyroid function at the beginning, sometimes with hyperthyroidism, but In the later stage, it often shows hypothyroidism. Many autoantibodies against thyroid are often detected in the body, but the process of inflammation and cytotoxic damage is still unclear. It is found that TSH receptor inhibitory antibodies can bind to TSH receptors. The role of TSH may be related to the hypothyroidism; the appearance of microsomal antibodies (actually peroxidase antibodies) may inhibit the synthesis of thyroid hormone to a certain extent; the deposition of thyroglobulin and its antibody complex in the thyroid may damage the thyroid gland And activation of "K" cells, (2) after radiotherapy: more common in Graves' disease after radioactive iodine treatment, the incidence of hypothyroidism increases with time, many cases of hypothyroidism within 1 year after iodine treatment (with dose There is a certain relationship), and the annual incidence of hypothyroidism (independent of dose) is about 1% to 5%. Early hypothyroidism is associated with acute radiation thyroiditis. Save low dose radiation may inhibit or destroy the DNA, which ultimately leads to the regeneration stop thyroid cells, in addition, the radiation can also cause neck cancer treatment of hypothyroidism.

Surgical factors (25%):

After thyroid cancer for total thyroidectomy; the occurrence of hypothyroidism after total resection of Graves disease is related to the number of residual thyroid gland and the integrity of blood supply. The annual incidence of postoperative permanent hypothyroidism is reported to be 1% to 2%.

Drug factor (5%):

Excessive antithyroid drugs (including thioureas and imidazoles); others such as salicylic acid, phenylbutazone, potassium perchlorate, cobalt, lithium and amiodarone can also cause hypothyroidism.

Other (30%):

Hypothyroidism is mainly caused by the decrease of TSH secretion caused by pituitary lesions or lesions of the pituitary attachment. It is common for pituitary tumors. After pituitary surgery or radiotherapy, patients with craniopharyngioma and Xihan disease enter old age, and a small number can be released by hypothalamic lesions. Caused by insufficient.

Pathogenesis:

Thyroid hormone deficiency affects all tissues of the body, so the symptoms are multifaceted. The most important pathophysiological changes caused by thyroid hormone deficiency are a large amount of extracellular mucinous substances in the interstitial space of the whole body. The substance is composed of acid mucopolysaccharide. a combination of (hyaluronic acid, chondroitin sulfate) and protein, a mucin that is highly hydrophilic, absorbs a large amount of water, deposits in the interstitial spaces of tissues, and is gradually expressed on the skin. Acidic mucopolysaccharide infiltrates and swells, keratinizes the surface of the skin, shrinks, and has a specific "mucinous edema" in the hair follicle and keratinized embolization of the sweat gland. The myocardial cells are contaminated by mucin and acid mucopolysaccharide, and interstitial edema. Myocardial tension is diminished, the heart is loose and enlarged, and it is a pseudo-hypertrophy of the heart muscle. In severe cases, myocardial fiber breaks, cell necrosis, pericardial effusion, large, cerebellum and hypothalamus can also have edema and degeneration, causing mental retardation, dementia, Nerve atrophy and decreased body temperature.

Prevention of senile hypothyroidism

1. Effectively control hypothyroidism, avoid overwork, trauma, hunger, and cold.

2. Regularly check for thyroid function.

3. Avoid eating foods rich in iodine, such as kelp, seaweed, etc.

Complications of senile hypothyroidism Complications, edema, coma, hypotension

Mucinous edema coma: is a hypothyroidism, easy to occur in elderly patients, the mortality rate is as high as 50% or more, the main cause of severe hypothyroidism has not been treated, under infection, trauma, hunger, cold and other stress On the basis of the clinical manifestations of hypothyroidism, the body temperature does not rise, the skin is dry and cold with yellow edema, slow heart rate, slow breathing and weakness, low blood pressure, lethargy, hibernation, and gradually into a coma.

Symptoms of senile hypothyroidism Common symptoms Mucinous edema face nausea and vomiting Hypothyroid function Low appetite loss Dementia Hair dry expression Depression Fatigue sleepiness depression

In the elderly, hypothyroidism is insidious, and only a small number of patients have characteristic clinical manifestations and physical symptoms - fatigue, dullness, depression, myalgia, constipation and dry skin, but sometimes even if the above performance is often mistaken for aging Caused by, not being noticed and valued, resulting in missed diagnosis.

1. General symptoms: decreased activity, dullness, depression, lack of lazy words, chills and sweats, body temperature below normal, hoarseness, deafness and loss of taste.

2. Face and skin: facial expression is indifferent, pale sallow and pale, eyelids and cheeks are swollen, forming mucous edema face; dry skin thickening, rough desquamation is non-indentation edema, due to increased carotene in the blood, skin can It is light yellow, due to increased blood cholesterol, yellow tumor can appear; nails are crisp and thick; hair is dry, brittle and dull, slow growth, even stop growing, eyebrows are sparse, outer 1/3 fall off; pubic hair and mane are sparse Fall off.

3. Cardiovascular system: slow pulse, low heart sound, low blood pressure, decreased cardiac output, bilateral general increase in the heart, arrhythmia is rare, because the sensitivity of hypothyroidism to catecholamines decreases, after a long time, heart Muscle fiber swelling and degeneration, myocardial interstitial mucin and mucopolysaccharide deposition, edema and interstitial fibrosis, called hypothyroidism, but the incidence of heart failure is low, occurs in patients with hypothyroidism without hormone replacement therapy Heart failure needs to be alert to the existence of other organic diseases. The incidence of coronary heart disease in patients with hypothyroidism is significantly increased, but due to decreased tissue metabolism, myocardial oxygen consumption is reduced, and typical angina is rare.

Serous effusion: in patients with long-term hypothyroidism, there is a fluid in the serosal cavity. Among them, pericardial effusion is more important. It is characterized by unsatisfactory heart rate and large amount of fluid. However, due to its slowness, it usually does not cause pericardium. Liquid tamponade symptoms, high pericardial fluid, high concentration of protein and cholesterol, and a small number of cells; sometimes accompanied by pleural effusion and ascites, which may be due to increased capillary permeability and local mucinous edema Water-based mucopolysaccharide and mucin accumulation.

4. Digestive system: patients with frequent tongue hypertrophy, decreased gastrointestinal motility caused by loss of appetite, vomiting, bloating, constipation, and even paralytic ileus, many patients have complete gastric acid deficiency, may affect the gastric mucosa due to autoimmunity, stomach wall The cause of cellular autoantibodies, the liver may have interstitial edema, the process of conversion of intrahepatic carotene into vitamin A, resulting in high caroteneemia.

5. Mental nervous system: mental and memory loss, slow feeling, slow response, but understanding is acceptable, lethargy, advanced severe cases can appear mental disorders, stupor and dementia, and even coma, sensitive to sedatives, can be induced after taking Coma, mental symptoms are generally associated with cerebral arteriosclerosis and decreased brain cell metabolism of oxygen and glucose; cerebellar hernia: ataxia, clumsy hands and feet, unclear speech and nystagmus; cranial nerves: sense of smell, taste, vision And hearing loss, even deafness; deep sputum reflex: knee reflex and sacral reflex is slow or disappear, mucinous edema coma is the most serious manifestation of this disease, can cause death within hours and days, more common in the long-term 60 years old Patients who have not been diagnosed and treated are more common in winter. Due to the lowering of the ambient temperature, the body's need for thyroxine is increased, mucinous edema is worsening, the patient's lethargy is becoming more and more serious, and even the consciousness is lost. The coma often develops slowly within a few days. Sometimes it can happen suddenly in infection, trauma, surgery, anesthesia and sedatives. Clinical manifestations include lethargy and hypothermia. , hypotension, hypoglycemia, bradycardia, difficulty breathing and muscle relaxation of the limbs, may be associated with shock and heart and lung failure and life-threatening, the exact mechanism of coma is not clear, may be a combination of multiple factors: low body temperature makes brain cells Can not work properly, high inhibition; subarachnoid or choroid plexus edema degeneration, resulting in increased cerebrospinal fluid pressure; hypoglycemia, decreased utilization of oxygen and glucose in brain cells; hypothyroidism increased respiratory resistance, decreased lung capacity and alveolar ventilation The blood carbon dioxide concentration is significantly increased, carbon dioxide anesthesia occurs; hypothyroidism patients often have cerebral arteriosclerosis, combined with hypotension, cerebral blood flow is significantly reduced; in addition, thyroxine deficiency itself can hinder the activity of many important enzyme systems in brain cells, also with the brain Related to dysfunction.

6. Muscle and bone joint system: Muscle weakness, mainly involving shoulder, buttocks muscle, occasional myasthenia gravis, muscle rigidity and muscle pain are common; bone metabolism is reduced, bone formation and absorption are reduced, bone density is increased, urinary sputum Decreased excretion of isotonic acid, etc., may have non-specific joint pain.

For fear of cold, less sweat, constipation, loss of appetite and increased weight, dry skin, yellow skin of the palm, memory loss, unresponsiveness, hoarseness and edema, or extensive ST-T changes, low voltage, Even patients with pericardial effusions such as pericardium have a thyroid function test in time, and the diagnosis is not difficult.

Examination of senile hypothyroidism

1. General inspection:

(1) often have mild to moderate normal cell type and positive pigment anemia, a small number can also see small cell hypopigmentation and large cell anemia, but hemoglobin is rarely <100g / L, the common cause of anemia may be iron, folic acid and vitamins B12 deficiency is related. In addition, thyroxine can stimulate bone marrow hematopoiesis to a certain extent. The lack of thyroxine will make the bone marrow hematopoietic function relatively inhibited.

(2) moderate to severe hypothyroidism can be seen serum cholesterol, triglyceride, creatine phosphokinase, aldolase, aspartate aminotransferase, etc. can be elevated; hyponatremia with or without antidiuretic hormone inappropriate secretion syndrome It can be seen that glomerular filtration rate, renal blood flow and renal tubular secretion capacity can be reduced, uric acid excretion is reduced, so blood uric acid is increased; blood glucose is normal or low, and the oral glucose tolerance curve is low.

2. Thyroid function test:

(1) Determination of basal metabolic rate: often less than -20%, about 80% of patients have a basal metabolic rate between -20% and -40%, and the degree of decline is often proportional to the severity of the disease. The metabolic rate rises to the normal range, but the basal metabolic rate has many influencing factors, and the results are often higher than the actual values.

(2) thyroid iodine rate: hypothyroidism patients rarely have radioactive iodine deposition, the iodine intake rate is lower than normal, showing a low flat curve.

(3) TSH measurement: due to the reduction of thyroid hormone, the feedback inhibition of pituitary TSH is reduced, so the secretion of TSH is increased, and the degree of increase reflects the degree of thyroxine decline in blood. It is the most sensitive indicator for the diagnosis of hypothyroidism. TSH is measured by radioimmunoassay. Normal people <10U/ml, TSH is measured by sensitive immunoradiometric method, and normal people are mostly in 0.3~5U/ml. If TSH is normal, hypothyroidism can be ruled out, mild hypothyroidism (subclinical hypothyroidism or weighing) Compensatory hypothyroidism: TSH increased, T3 and T4 were normal, no clinical manifestations of hypothyroidism) TSH was 5-15 U/ml; clinical hypothyroidism TSH was more than 20 U/ml. In addition, TSH assay was used to identify primary hypothyroidism. And secondary hypothyroidism also has important value, the primary hypothyroidism TSH increased, and the secondary hypothyroidism TSH decreased or normal.

(4) T4 and T3 determination: including TT4, TT3, FT4 and FT3 determination, TT4 can be determined by radioimmunoassay, which includes binding and free T4, which is a direct measurement of thyroxine. When hypothyroidism, TT4 is often <3g/ Dl, the decline of TT3; TT3 measurement has little value in the diagnosis of hypothyroidism, about 30% of patients with clinical hypothyroidism TT3 is normal, only in the late and severe cases, TT3 decreased <100g / dl; anti-T3 is often significantly reduced The normal value is 47±10g/dl. The T4 and T3 yields are insufficient in this disease, and the T4 is converted to T3 tends to increase to compensate for hypothyroidism, so that the anti-T3 decreases, often <20±8g/dl; FT4 can directly respond. Thyroid function; is the most reliable indicator for the diagnosis of hypothyroidism, the diagnostic coincidence rate is 100%, the diagnostic value of FT3 for hypothyroidism is lower than TT4, and the order of sensitivity to hypothyroidism is generally: TSHFT4>TT4>FT3>TT3.

(5) TSH stimulation test: It is often used to identify primary and secondary hypothyroidism before TSH can be measured. It is rarely used now. It can understand the thyroid reserve function by changing the thyroid iodine rate before and after intramuscular injection of TSH. TSH 10U was intramuscularly injected every day for 3 days. The thyroid iodine rate was measured before and after intramuscular injection of TSH (3h and 24h). If the thyroid iodine absorption rate was significantly increased, it suggested secondary hypothyroidism, and no increase was primary. Hypothyroidism, this method has the following disadvantages: oral radioactive iodine and radioactive exposure; expensive and time consuming; there may be an allergic reaction to animal TSH; for patients with secondary hypothyroidism, adrenal insufficiency may be induced, such as Giving glucocorticoids may even induce a crisis.

(6) TRH excitatory test: mainly used to identify secondary or primary hypothyroidism. After intravenous injection of TRH 200-500g, under normal conditions, TSH rises rapidly by 5~25U/ml, reaches a peak at 30min, and recovers at 120min. Normal, such as TSH showed a delayed increase, suggesting that the lesion may be at the level of the hypothalamus; if there is no increase in response, the lesion may be in the pituitary; if the TSH is higher, and the TRH is higher after stimulation, it is suggestive of primary hypothyroidism.

(7) Determination of thyroid autoantibodies: hypothyroidism associated with autoimmunity (mostly primary), several autoantibodies against the thyroid, such as TSH receptor inhibitory antibodies, microsomal antibodies, thyroid globules, are often measured in vivo. Protein antibodies and second glial antibodies, etc., TSH receptor stimulating antibodies can also be detected in some patients, the significance of which is not fully understood.

3. Imaging examination:

X-ray of the skull, stratified photography, computed tomography (CT), magnetic resonance imaging (MRI) or even ventriculography to examine the organic lesions of the pituitary or hypothalamus that cause hypothyroidism, but have not been treated for a long time. The pituitary and sella of patients with hypothyroidism can be secondary and even pituitary-like, and combined with clinical and laboratory findings.

4. Other:

Electrocardiogram showed sinus bradycardia, low voltage, T wave low or inverted, PR interval or QRS time limit sometimes extended, sometimes with atrioventricular block, echocardiography showed left ventricular diastolic and systolic function, pericardial dysfunction Fluid and asymmetrical ventricular septal hypertrophy, EEG can be diffuse abnormalities, low frequency, irregular rhythm, color transcranial Doppler often shows cerebral arteriosclerosis and cerebral blood flow reduction.

Diagnosis and diagnosis of senile hypothyroidism

Diagnostic points

Because the performance of hypothyroidism in the elderly is often indistinguishable from changes in aging or other senile diseases, especially in patients with subclinical hypothyroidism, there is no clinical clue. Therefore, laboratory thyroid function tests are the key to establishing a diagnosis. Without hypothyroidism, you should consider hypothyroidism and perform a thyroid function test:

1 have a history of chronic lymphocytic thyroiditis or other thyroiditis.

2 have had thyroid surgery or thyroid and neck radiation therapy for various reasons.

3 thyroid enlargement or nodules.

4 hyperlipidemia, especially those with elevated serum cholesterol.

5 There are other patients with autoimmune diseases.

Differential diagnosis

1. Normalthyroid sick sydrome (ESS), the patient is in normal thyroid function, and the thyroid function is abnormal in laboratory tests: serum T3 is decreased and anti-T3 is increased, TT4 is normal or decreased, TSH is not elevated, ESS Common in various acute and chronic non-thyroid diseases or stress, such as hunger, insufficient protein and long-term energy intake, severe trauma, myocardial infarction, chronic renal failure, diabetic ketosis, anorexia anorrhea, cirrhosis and sepsis, etc. At the time, T4 decreased to a decrease in T3 in the peripheral tissues, and the conversion to anti-T3 increased and the combination of thyroxine and thyroid-binding globulin decreased. If the anti-T3 was low, it suggested a combination of hypothyroidism, and ESS was mainly for the treatment of underlying diseases. .

2. Chronic nephritis (edema type) and nephrotic syndrome: The clinical manifestations and hypothyroidism of chronic nephritis and nephrotic syndrome have similarities, but the edema of patients with nephropathy is concave, retinal exudation and hemorrhage, and urine cells have red blood cells and proteins. Tube type and renal dysfunction are obvious.

3. Anemia: The patient's skin is pale, but patients with hypothyroidism are often more sensitive to cold, mental and physical activity is slow and hair loss, etc., laboratory tests are not difficult to identify.

4. Others: The clinical manifestations of hypothyroidism vary widely, often with a more prominent symptom, such as coronary heart disease or "unexplained" heart enlargement and visit the cardiovascular department; see the ENT because of hoarseness; Depression, mental disorders, and psychiatry, even admitted to a mental hospital; due to lethargy, movement disorders or hemiplegia, see a neurology; see a blood department due to anemia, such as a comprehensive understanding of the disease, and familiar with various Atypical symptoms, alert at any time, it is easy to misdiagnosis and missed diagnosis.

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