Hyperthyroidism in pregnancy

Introduction to pregnancy complicated with hyperthyroidism Normal maternal and fetal thyroid function is an important guarantee for fetal neuro-intellectual development. Hormonal and metabolic changes in normal pregnancy lead to a series of physiological changes in the thyroid gland and its related endocrine. In the case of adequate iodine supply, the thyroid function of pregnant women A balance will be reached at a new level, and a series of thyroid dysfunctions can occur in pregnant women if iodine is deficient or combined with other pathological factors. In pregnancy, hyperthyroidism, the vast majority of Grave disease, other including toxic goiter and rare subacute thyroiditis, toxic single adenoma. In addition, thyroid disease is improperly treated, and iatrogenic hyperthyroidism caused by excessive application of thyroxine. basic knowledge The proportion of illness: 0.002% - 0.009% Susceptible population: pregnant women Mode of infection: non-infectious Complications: atrial fibrillation

Pregnancy with hyperthyroidism

Autoimmune factors (25%):

The induction of hyperthyroidism is closely related to autoimmune, genetic and environmental factors, among which autoimmune factors are the most important. Unfortunately, the development of thyroid autoimmunity and the development process have not been known so far, so it is difficult to find a preventive method.

Environmental factors (35%):

Environmental factors mainly include various factors that induce the onset of hyperthyroidism, such as trauma, mental stimulation, infection, etc. Although the induction of many hyperthyroidism is mainly related to autoimmunity and genetic factors, it is closely related to environmental factors. If you encounter predisposing factors, you will not develop the disease. It can be seen that the onset of some hyperthyroidism patients may be prevented under the condition of avoiding the predisposing factors.

Genetic factors (15%):

Genetic factors are also important, but the genetic background and genetic approach have not been elucidated, so it is difficult to prevent them genetically.

Pathogenesis

Hyperthyroidism caused by different causes has different pathophysiological changes.

Diffuse toxic goiter

Also known as Graves disease, it is an autoimmune disease, accounting for 60% to 70% of patients with hyperthyroidism. It is prone to occur in genetically susceptible individuals. The incidence of women of childbearing age is high. Many women are diagnosed before pregnancy. After entering the pregnancy; some pregnant women, in the past have diffuse toxic goiter, after treatment has basically healed or have been completely cured after pregnancy, such patients have more prominent eyes, it is also called malignant ocular goiter, this type of hyperthyroidism women Pregnancy often requires medication to control the condition. Such patients have an immunoglobulin antibody, also known as thyroid-stimulating immunoglobulin (TSIG or TSAb), which was formerly known as long-acting thyroid stimulating hormone (LATS) and can pass through the placenta. Causes thyroid enlargement and hyperthyroidism in the fetus and newborn, TSH blocking antibody (TSBAb) in patients with Graves disease and Hashimoto's disease, and hypothyroidism in patients with Graves' disease when TMBAb is predominant (Kenneth, 1998), in the 20th century There have been many reports in the age of pregnant women with Graves disease that there are antibodies to the thyroid stimulating hormone receptor, the thyrotropin receptor antibody (TRAb), which acts on the thyroid gland. The receptor of TSH on the gland enhances iodine uptake by activating adenosine triphosphatase, causing excessive synthesis of T4 and T3 in the thyroid gland, causing hyperthyroidism in patients. When TSBAb passes through the placenta, it can cause hypothyroidism in the fetus and newborn. Thyroid gland is not swollen, TRAb stimulation and blocking antibodies can not be predicted separately (Gallagher, 2001), TSI in pregnant women with Graves disease, TRAb is immunoglobulin IgG, small molecule, easy to pass through the placenta, stimulate the fetal thyroid gland in the uterus, Maternal TRAb can now be determined. If the TSAb (TSI) titer is quite high enough to cause the fetus to produce high levels of T4, T3, then the fetus may develop hyperthyroidism in the uterus. Conversely, if the TSAb blocks the antibody TSBAb predominately, it may be Hypothyroidism occurs. If the mother takes anti-thyroid drugs, the drug can pass through the placenta and inhibit the production of T3 and T4. The balance between the two determines the function of the fetal thyroid. If the pregnant woman with Graves disease is not treated properly, the fetus can be in the uterus after being affected. There are complications such as hypothyroidism, hyperthyroidism, fetal death, limited fetal growth, premature birth, stillbirth, etc. Newborns can also have a wide range of self-improvement after birth. Sexual disease manifestations, such as general hypertrophy of lymphoid tissue, thrombocytopenia, can also have hyperthyroidism after birth, such as goiter with hypermetabolism, in most cases, hypermetabolism is temporary, because TSAb half-life is about 14 days, and anti- After the thyroid drug is severed, the symptoms of neonatal hyperthyroidism can last from 1 to 5 months after birth under the influence of TSI.

2. Subacute thyroiditis

Thyroid combined with other viral infections, early stage thyroid congestion, edema, and how many cell damages, so that thyroxine escapes into the blood circulation, temporary hyperthyroidism occurs, patients do not have TSAb, thyroid biopsy has characteristic changes That is, a multinucleated giant cell granulomatous lesion with lymphocytic infiltration, which is characteristic of thyroiditis.

3. Toxic nodular goiter and toxic thyroid adenoma

In many areas of iodine deficiency in the world, women with thyroid gland in the region may have single or multiple nodules, thyroid compensatory hyperplasia, single or multiple nodular goiter can develop into thyrotoxicosis, and hyperthyroidism, iodine deficiency The caused goiter or adenoma can be treated with exogenous iodine supplementation to relieve the disease. If there is hyperfunction due to a single thyroid adenoma, surgical resection can also be considered. Pregnant women with toxic multiple nodular goiter are rare. Most pregnant women need surgery to delay the postpartum period.

4. Chronic lymphocytic thyroiditis

Hashimoto's thyroiditis, also known as autoimmune thyroiditis, has thyroid autoantibodies, including thyroglobulin antibody (TGAb) and thyroid peroxidase antibody (TPO-Ab). The thyroid histology is Lymphocyte infiltration, connective tissue formation and glandular epithelial changes, thyroid enlargement, toughness, irregularity, early manifestation of hyperthyroidism, and then into the hypothyroidism, some patients are easily misdiagnosed as toxic goiter during hypermetabolism, thus removing part of the thyroid gland, pathology He was diagnosed with lymphocytic thyroiditis and needed to be supplemented with thyroid tablets later in his illness.

5. Trophoblastic disease

Such as hydatidiform mole and chorionic epithelial cancer, these patients have high levels of serum -HCG, stimulating thyroid, serum TT4 value can be 1 times higher than normal people, clinically, hyperthyroidism can occur, when the hydatidiform mole is removed by curettage After surgery for chorionic epithelial cancer, serum -HCG levels are lowered, serum TT4 is decreased, and hyperthyroidism symptoms are naturally lost.

Pregnancy with hyperthyroidism prevention

1 Coastal areas should pay attention to iodine-containing foods in the diet. It is recommended not to use high-iodine diet to prevent iodine. 2 Inland areas (iodine-deficient areas) should have a limited date for iodine supplementation, and thyroid tablets should also be time-limited. 3 census physical health, should be measured thyroid B ultrasound or thyroid function to early detection of hyperthyroidism patients, passive detection of hyperthyroidism patients, the condition is often delayed for 2 to 3 years.

Avoid mental incentives, regular life, work and rest, and it is good for preventing the disease. For hyperthyroidism caused by external use, as long as avoiding inappropriate or abusing thyroid preparations or iodine-containing drugs, it can completely prevent the occurrence of iatrogenic hyperthyroidism. It is also very difficult to prevent hyperthyroidism. However, as long as the diet is regular, the daily life is normal, the work is unruly, the ignorance is nothing (selfish desire, comfortable mood, happy spirit), conforming to the laws of nature, and appropriate physical exercise, not only can enhance the body's immune function, but also It also has certain positive significance in preventing the occurrence of hyperthyroidism.

Pregnancy complicated with hyperthyroidism Complications, atrial fibrillation, coma

The most important effect of pregnancy with hyperthyroidism on the mother is thyroid crisis. Once the mortality rate can be as high as 25%, the crisis often occurs in certain stress states such as childbirth, surgery (cesarean section), infection, etc. Commonly seen in childbirth or a few hours after surgery, clinical symptoms can be seen with high fever (>40 ° C), tachycardia disproportionate to body temperature, atrial fibrillation can also occur, other symptoms can have vomiting, abdominal pain, diarrhea, dehydration, and the central nervous system Symptoms such as restless convulsions, and even coma.

Pregnancy with hyperthyroidism Symptoms Common symptoms Increased heart rate, easy to be excited, tired, goiter, nausea, suspicion, diarrhea, skin itching, sweating, depression

Typical patients with high metabolic syndrome, goiter, and exophthalmos are the main manifestations. The onset of this disease is slow, and it is often difficult to determine the date of onset. Generally, a few months before the definitive diagnosis, hyperthyroidism has been present. Only pregnant hyperemesis Nausea and vomiting, hand tremors and palpitations and other symptoms are promptly diagnosed, the most common complaints are personality changes, nervousness, irritability, excitement, multi-speaking and suspicious, lack of concentration or ignorance, palpitations Hairy or persistent), easy to get tired, fear of heat (less common people cover when sleeping), weight loss, increased bowel movements, a few have diarrhea, skin itching or rash after sun exposure, Grave disease has typical triad : Hyperthyroidism, exophthalmos, anterior humeral edema, which is thought to be caused by TSH-specific autoantibodies that bind to TSH receptors and activate receptors. Typical symptoms are nervousness, fear Heat, heart palpitations, sweating, diarrhea, weight loss, physical examination can reveal typical signs: exophthalmos, sputum reflex, tachycardia, tremor, skin tide And warm, goiter, can be found that the thyroid is diffuse, symmetry is increased (2 to 3 times normal), the quality from soft to strong varies from individual to individual, rarely tender, smooth surface, but irregular or It is not uncommon for people to have a leaf-like structure. Occasionally, those who touch the isolated nodules in diffusely enlarged glands should be further examined to detect tremors and murmurs. The latter two are specific signs of hyperthyroidism. .

Due to excessive sweating, the skin is often hot and tidal, especially the palm is more obvious. Occasionally, the palm erythema and telangiectasia are dilated, the hair is thin and brittle, easy to fall off, and some have cracked nails. The distal end of the nail is separated from the nail bed. The so-called Plummer A, the hand and tongue have tremor phenomenon, there are a few cases of localized visceral edema in the lower part of the lower leg of the lower leg. Due to different degrees of muscle weakness, in the sitting or lying position, you must use the strength of your hand to stand up.

Cardiovascular function changes are also one of the most prominent clinical manifestations. There are often tachycardia, heart rate is often >90 beats/min. Peripheral vascular resistance decreases at rest, heart rate increases, stroke volume increases, and cardiac output increases. The systolic blood pressure is increased, the diastolic blood pressure is decreased, the pulse pressure difference is increased, the apical beat range is expanded and powerful, the heart sound is strengthened, the systolic phase and the precontraction murmur are audible in the apex, and about 10% of patients even have atrial fibrillation and no heart disease. Heart disease can also occur in pregnant women with this disease.

The clinical symptoms of hyperthyroidism during pregnancy are the same as those during non-pregnancy, such as thyroid enlargement, palpitations, tachycardia, excessive sweating, fear of heat, loss of appetite and weight loss, fatigue, diarrhea, finger tremor, goiter, and exophthalmos. Hyperthyroidism can be aggravated in early pregnancy and stable in the middle and late stages.

Pregnancy with hyperthyroidism

The following results are higher than the normal high limit, but the TSH value is decreased:

1 serum total thyroxine (TT4): 68.9 ~ 210.6nmol / L.

2 serum total triiodothyronine (TT3): (1.386 ~ 3.388) nmol / L.

3 free thyroxine (FT4): (32.5 ± 6.5) pmol / L.

4 free T3 (FT3): (6.0 to 11.4) pmol / L.

5 thyroxine-binding globulin (TBG): (20 ~ 48) mg / L.

6 resin triiodothyronine uptake ratio (RT3U): 0.9 ~ 1.1.

7TSH: 10mU/L.

8 free thyroxine index (FT4I = TT4 × RT3U: 2.23 ~ 14): the application of FT4I value can correct the illusion of increased TT4 due to the increase in the amount of TBG. Ultrasonography: Color Doppler ultrasonography showed diffuse or focal echo reduction in the thyroid gland. At the echo reduction, the blood flow signal increased significantly. CDFI showed "fire sea sign", upper thyroid artery and gland. The internal artery flow rate is significantly accelerated and the resistance is reduced.

Diagnosis of pregnancy complicated with hyperthyroidism

diagnosis

Patients with typical symptoms and signs, diagnosis is not difficult, laboratory tests can help to confirm the diagnosis, FT3 and FT4 are the main indicators of diagnosis, hyperthyroidism is significantly elevated, T3, T4 and thyroid-binding globulin are also significantly increased, TSH Reduced by suppression.

Note: Some symptoms and signs of hyperthyroidism such as tachycardia, fear of heat, and systolic murmurs in the thyroid gland may be mistaken for physiological phenomena during pregnancy.

Differential diagnosis

Care should be taken to identify the following diseases.

1. Simple goiter during pregnancy

Especially pregnant women are neurotic, their mental and emotional performance is very similar to hyperthyroidism pregnant women, but the pulse <100 times / min, pulse pressure difference <50mmHg (6.7kPa), cold palm, no micro tremor, normal knee reflex, thyroid enlargement Not significant, no vascular tremor and murmur can be heard, no eye gaze and exophthalmos, laboratory sera check various thyroid function indicators are within the normal range of pregnancy.

2. Subacute thyroiditis

(1) Hyperthyroidism: the most common thyroid disease in adolescent or advanced pregnant women during pregnancy. Patients often have clinical manifestations of hypermetabolism, such as heart palpitations, fear of heat, sweating, nervousness, irritability, hand shake and other hyperthyroidism. Serum TT4, TT3, FT4, FT3, etc. are elevated, so often misdiagnosed and given ATD treatment, but patients often have a history of viral infection, rapid onset, chills and fever, the most characteristic is thyroid enlargement, pain, Swelling and pain can start from one side and then expand to the other side, which in turn affects the whole thyroid gland. The diseased gland is hard and tender, and the pain is aggravated when chewing, swallowing, turning the neck or bowing, and the erythrocyte sedimentation rate is significantly accelerated (50 ~100mm/h).

(2) Remission period: When entering the remission period, the thyroid swelling and pain are alleviated, and the serum T4 and T3 concentrations are decreased.

3. Hashimoto disease

It is one of the main causes of thyroid enlargement. It is often caused by unexplained heartbeat, shortness of breath, chest tightness, and weakness of the limbs. The diagnosis of hyperthyroidism is extremely difficult. The two autoimmune diseases can coexist at the same time, called Hashitoxicosis. Hashimoto's thyroiditis has a large goiter, strong and occasional tenderness. It is difficult to identify the serum in the laboratory during hyperthyroidism. The cytological examination can be performed with small needle puncture. The result is accurate, reliable, simple and safe.

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