Hyperthyroidism during pregnancy

Introduction Hyperthyroidism (hyperthyroidism) is a common endocrine disease caused by excessive secretion of thyroid hormone. Women with hyperthyroidism often present with menstrual disorders, reduced or amenorrhea, and low fertility. However, among the untreated women with hyperthyroidism after treatment, there are many pregnant women, and the incidence rate is about 1:1000-2500 pregnancies. Most of the hyperthyroidism during pregnancy is Graves' disease, which is mainly caused by autoimmune and mental stimulation, characterized by diffuse goiter and exophthalmos. The cause of hyperthyroidism during pregnancy is basically the same as that of non-pregnancy hyperthyroidism, of which Graves disease is the most common. Followed by toxic nodular goiter, thyroid autonomic adenoma and so on. In addition, hyperthyroidism can occur in hyperemesis, hydatidiform mole, malignant mole, and chorionic epithelial cancer.

Cause

The cause of hyperthyroidism during pregnancy is basically the same as that of non-pregnancy hyperthyroidism, of which Graves disease is the most common. Followed by toxic nodular goiter, thyroid autonomic adenoma and so on. In addition, hyperthyroidism can occur in hyperemesis, hydatidiform mole, malignant mole, and chorionic epithelial cancer.

The cause of Graves' disease is not well understood, but patients have familial qualities. About 15% of relatives have the same disease, and about 50% of their families have positive anti-thyroid antibodies. Many studies have suggested that Graves disease is an autoimmune disease (AITD). Because immune dysfunction can cause multi-lymphoid factors and thyroid autoantibodies in the body, antibodies bind to TSH receptors on the thyroid cell membrane, stimulating thyroid cell proliferation and function enhancement. This antibody is called thyroid-stimulating immunoglobulin (TSI). The presence of TSI in the blood circulation is significantly associated with the activity and recurrence of hyperthyroidism, but the factors that cause this autoimmune response are unclear. Olpe believes that the patient has immunomodulatory defects, inhibits the loss of T lymphocyte function, and allows the helper T lymphocytes to freely stimulate lymphocytes to produce immunoglobulin, which acts directly on the thyroid gland. TSI in the globulin stimulates the thyroid gland to enhance thyroid function. Kriss believes that the infiltrative exophthalmos of Graves' disease is caused by the deposition of thyroglobulin anti-thyroglobulin immune complex in the orbital muscle, resulting in an immune complex inflammatory response; another hypothesis is that the eye muscle acts as an antigen and helper T lymphocytes. The interaction between the two causes an autoimmune immune response. The mechanism of skin lesions in thyroid patients is still unclear, and may also be the manifestation of autoimmune lesions in the skin before the sputum.

an examination

Related inspection

Serum total thyroxine (TT4) free thyroxine index (FT4I) total triiodothyronine (TT3) basal metabolic obstetrics B-ultrasound

Normal pregnancy is similar to the clinical manifestations of hyperthyroidism in many aspects due to changes in maternal thyroid morphology and function, so it is difficult to diagnose pregnancy with hyperthyroidism. When symptoms and signs of hyperthyroidism are found during prenatal examination, the thyroid function should be further tested to confirm the diagnosis. The diagnostic criteria for hyperthyroidism during pregnancy are: high metabolic syndrome, serum total thyroxine (TT4) 180.6nmol/L (14g/dl), total triiodothyronine (TT3)3.54nmol/L (230ng/ Dl), free thyroxine index (FT4I) 12.8. The condition of hyperthyroidism is 1.4 times the normal limit of TT4 and the upper limit of normal is hyperthyroidism; there are severe hyperthyroidism such as crisis, hyperthyroidism, heart failure and myopathy.

1, serum free thyroxine (FT4) and free triiodothyronine (FT3) FT3, FT4 is the active part of circulating blood thyroid hormone, it is not affected by changes in blood TBG, directly respond to thyroid function status. It has been widely used in clinical practice in recent years, and its sensitivity and specificity are significantly higher than total T3 (TT3), total T4 ((TT4), normal value FT4 9-25 pmol/L; FT33-9 pmol/L (RIA), each experiment There are certain differences in room standards.

2, serum thyroxine (TT4), is the most basic screening index for judging thyroid function, more than 99.95% of serum T4 and protein binding, of which 80% -90% combined with globulin called thyroxine-binding globulin (TBG) TT4 refers to the total amount of T4 binding to protein, which is affected by the amount of binding protein and binding force such as TBG; TBG is also affected by factors such as pregnancy, estrogen and viral hepatitis, and is affected by androgen and low protein blood. Symptoms (severe liver disease, nephrotic syndrome), prednisone and other effects decreased. Care must be taken when analyzing.

3, serum total triiodothyronine (TT3) serum T3 and protein binding more than 99.5%, also affected by TBG, TT3 concentration changes often parallel with TT4 changes, but the early recurrence of hyperthyroidism, TT3 rise It is often very fast, about 4 times normal, TT4 rises slowly, only 2.5 times normal, so TT3 is a sensitive indicator for the diagnosis of the disease; for the beginning of the disease, the efficacy of the treatment and the recurrence of the recurrence It is more sensitive, especially for the diagnosis of T3 hyperthyroidism to obtain specific indicators. It should be noted that the elderly patients with apathetic hyperthyroidism or chronic disease TT3 may not be high.

4, serum anti-T3 (revrseT3, rT3) rT3 no biological activity, is the degradation product of T4 in peripheral tissues, its blood concentration changes with T4, T3 maintain a certain proportion, especially consistent with T4 changes, can also be used to understand the thyroid Functional indicators, some of the early stage of the disease or early relapse only rT3 increased as a more sensitive indicator. In severe malnutrition or certain systemic disease states, rT3 is significantly elevated, while TT3 is significantly reduced, which is an important indicator for the diagnosis of low T3 syndrome.

5. TSH immunoradiometric assay (sTSH IRMA): The sTSH level in the normal blood circulation is 0.4-3.0 or 0.6-4.0 IU/ml. Using IRMA technology to detect the lower limit of normal level, the minimum detection value of this method is generally 0.03IU/ml, which has high sensitivity, so it is also called sTSH ("sensitive" TSH). Widely used in the diagnosis and treatment monitoring of hyperthyroidism and hypothyroidism.

6, thyroid hormone release hormone (TRH) stimulation test: hyperthyroidism serum T4, T3 increased, feedback inhibition of TSH, so TSH is not excited by TRH, such as intravenous injection of TRH200G TSH increased, can rule out the disease; such as TSH does not increase ( No response) supports the diagnosis of hyperthyroidism. It should be noted that the increase of TSH can also be seen in Graves' ophthalmopathy with normal thyroid function, pituitary lesions and insufficient secretion of TSH. The side effects of this test are few, and it is safer for patients with coronary heart disease or hyperthyroidism than T3 inhibition test.

7, 131I rate of thyroid: the coincidence rate of this method for the diagnosis of hyperthyroidism is 90%, iodine-deficient goiter can also be elevated, but generally no peak advance, can be used for T3 inhibition test identification, this method can not reflect the severity of the disease Changes with the condition of the treatment, but can be used to identify hyperthyroidism of different causes, such as the low rate of 131I may be thyroiditis with hyperthyroidism, iodothyroid or exogenous hormone caused by hyperthyroidism. It should be noted that this law is affected by a variety of foods and iodine-containing drugs, including traditional Chinese medicines, such as anti-thyroid contraceptives, which should be stopped for more than 1-2 months before the measurement, and disabled during pregnancy and lactation. . Normal value: measured by Geiger counter tube, the values of 3 and 24 h were 5%-25% and 20%-45%, respectively, and the peak appeared at 24h. Hyperthyroidism: 3h>25%, 24h>45%: and the peak shifts forward.

8, triiodothyronine inhibition test: referred to as T3 inhibition test. Used to identify goiter with a 131I rate increase caused by hyperthyroidism or simple goiter. Methods: First, take the basic 131I rate, oral, T320g, 3 times a day for 6 days (or oral dry thyroid tablets 60mg, 3 times a day, even for 8d, then take 131I rate. Compare the two results, normal The rate of 131I in patients with simple goiter is more than 50%, and the rate of 131I in patients with hyperthyroidism can not be suppressed. The rate of 131I is less than 50%. This method is forbidden for those with coronary heart disease or hyperthyroidism, so as not to induce arrhythmia or angina. .

9. Determination of thyroid stimulating antibody (TSAb): The positive detection rate of TSAb in GD patients can reach 80%-95%. It is not only useful for early diagnosis of this disease, but also valuable for judging disease activity and recurrence. As an important indicator of treatment discontinuation.

Differential diagnosis

Symptoms similar to normal pregnancy: symptoms of hyperthyroidism during normal pregnancy: increased heart rate, increased heart rate, increased thyroid 30%-40%, hyperhidrosis, heat, and appetite; laboratory tests TT3 TT4 is slightly increased.

Normal pregnancy is similar to the clinical manifestations of hyperthyroidism in many aspects due to changes in maternal thyroid morphology and function, so it is difficult to diagnose pregnancy with hyperthyroidism. When symptoms and signs of hyperthyroidism are found during prenatal examination, the thyroid function should be further tested to confirm the diagnosis. The diagnostic criteria for hyperthyroidism during pregnancy are: high metabolic syndrome, serum total thyroxine (TT4) 180.6nmol/L (14g/dl), total triiodothyronine (TT3)3.54nmol/L (230ng/ Dl), free thyroxine index (FT4I) 12.8. The condition of hyperthyroidism is 1.4 times the normal limit of TT4 and the upper limit of normal is hyperthyroidism; there are severe hyperthyroidism such as crisis, hyperthyroidism, heart failure and myopathy.

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