high iodine goiter
Introduction
Introduction to high iodine goiter Iodine mainly enters the body with food and drinking water. During the process of digestion and absorption, most of the organic iodine and elemental iodine are reduced to inorganic iodide (I-), which can be absorbed by the small intestine. The amount of iodine ingested in the diet varies greatly depending on dietary habits and the amount of iodine in the local soil and water. Under normal dietary conditions, the daily intake of iodine from food in China is about 100-200g. According to Chinese standards, the physiological requirement of iodine per day for normal adults is 120-150g, pregnant women or lactating mothers are 200-250g, infants and young children are 20 30g, 5080g for children and 160200g for adolescents. In the intake of iodine, only a small part is thyroid uptake, most of which is excreted by the kidney. The minimum requirement for iodine in normal adults is about 100-150g per day. basic knowledge The proportion of illness: the probability of illness is 0.14% Susceptible people: no specific population Mode of infection: non-infectious Complications: chronic lymphocytic thyroiditis simple goiter
Cause
Causes of high iodine goiter
(1) Causes of the disease
1. Residents in coastal areas drink high-iodine water or food.
2. Xinjiang, Shanxi, Inner Mongolia, and other highlands that are mostly extended by basins or mountains. Due to the flooding of iodine-rich water deposits caused by ancient floods, inland high-iodine goiter has emerged.
(two) pathogenesis
The mechanism is unclear. The usual explanation is the iodine blocking effect, namely the Wolff-Chaikoff effect. The classical explanation is: when ingesting high iodine, iodine inhibits the activity of peroxidase and reduces the synthesis of T3 and T4. Increased feedback TSH secretion promotes the occurrence of goiter. Recent studies have shown that high iodine intake mainly inhibits sodium-iodide symptom (NIS), which reduces the transport of iodine into thyroid cells. Caused by decreased intracellular iodine levels, decreased T3, T4 synthesis, increased feedback TSH secretion, promoted the occurrence of goiter, however, the iodine blocking effect is temporary, most people quickly adapt, called iodine blocking escape Epstein, most people do not have high-iodine goiter, long-term intake of high iodine, although the body's adaptation can keep hormone metabolism normal, but due to excessive gelatinization and retention, high iodine inhibits protein off Iodine eventually causes the follicular cavity to expand and form a goiter.
In patients with hyperthyroidism, the thyroid follicles are obviously swollen, the glial is increased, and the epithelial cells are flat; however, some epithelial cells show columnar or hyperplastic changes, some follicles fuse, and the vesicles become smaller or more prominent. Follicles, thyroid interstitial fibrosis and early nodule changes, animal tests of high iodine mice show that thyroid caused by high iodine is a follicular glial retention goiter, thyroid follicles are highly dilated, epithelial cells are flat, and vesicles Significantly enlarged, the cavity is filled with gelatin.
Prevention
High iodine goiter prevention
The problem of high iodine is a problem that has only appeared in recent decades. With the continuous development of the prevention and treatment of iodine deficiency disorders in China and the deepening of the research on the relationship between iodine and health, the harm to high iodine and its health will become clearer. It is recognized that all localities in China are working hard to improve the structure of drinking water. Health institutions at all levels should strengthen monitoring, timely discover new high-iodine wards or high-iodine areas, and strive to take necessary measures to reduce or eliminate the danger of high iodine.
1. Limit the intake of high iodine in people with high iodine; contraindications to iodized salt, otherwise it will cause the prevalence of high iodine goiter.
2. Coastal high iodine areas are fasted to pickled kelp salt and eat common salt.
3. Improve drinking water structure in high-iodine areas, and health institutions at all levels to strengthen drinking water monitoring.
4. For sporadic high-iodine goiter, pay attention to the above-mentioned situation that is easy to cause high iodine. Try to avoid using iodine or reduce the dosage and follow up closely. Pay special attention to iodine for pregnant women. Otherwise, the newborn may have high iodine thyroid gland. Swelled and even suffocated to death.
Complication
High iodine goiter complications Complications chronic lymphocytic thyroiditis simple goiter
The mechanism of hyperthyroidism-induced hypothyroidism is similar to that of iodine-induced goiter, but only to a more severe degree, or at the same time combined with other thyroid dysfunction, such as chronic lymphocytic thyroiditis, swollen thyroid function can not be compensated to Normal, resulting in dysfunction, in the TPO-Ab positive population, the incidence of hypothyroidism in different iodine intake was significantly different, with the increase in iodine intake, the incidence of hypothyroidism gradually increased, and the higher the antibody titer The higher the incidence of hypothyroidism, the increased iodine intake may increase the risk of subclinical and clinical hypothyroidism in people with thyroid autoimmune abnormalities. A clinical prospective study in Germany indicates that in areas with moderate iodine deficiency Patients with normal thyroid function and positive thyroid autoantibodies or thyroid B ultrasound for hypoechoic administration took 250 g of potassium iodide daily. After 4 months, subclinical and clinical hypothyroidism were significantly higher than those without iodine.
Defects in iodine organicization of congenital or acquired thyroid gland, the risk of hypothyroidism-induced hypothyroidism is greatly increased, and patients with simple goiter caused by iodine organic deficiencies are most likely to have hypothyroidism-induced hypothyroidism, a prospective Sexual study of iodine in patients with chronic lymphocytic thyroiditis with normal thyroid function, can produce high iodine-induced hypothyroidism, stop iodine, thyroid function returns to normal, these patients may continue to exist iodine Wolff-Chaikoff effect There is no escape. In recent years, the incidence of chronic lymphocytic thyroiditis with hypothyroidism or goiter has increased in the United States. This is due to the long-term chronic high iodine intake leading to the deficiencies in the iodine iodine. Hypothyroidism is also likely to occur in patients with Graves who have previously had 131I or surgery, but not all patients cause high iodine-induced hypothyroidism, which may be a potential iodine-organic disorder. Radiotherapy has increased thyroid iodine. Disorders, fetuses and newborns Iodine induced hypothyroidism, amiodarone when treating arrhythmia due to competitive inhibition of the levels of T3 receptor -, prone to cause hypothyroidism.
The clinical features of hyperthyroidism-induced hypothyroidism are diverse. Simple goiter is more common than hypothyroidism. Most of them are moderate to severe thyroid diffuse enlargement, often with chronic lymphocytic thyroiditis, Graves' disease or goiter. History, mild or lack of signs and symptoms of hypothyroidism, serum T4 and TSH values normal or normal lower limit, TRH stimulation test showed that TSH abnormal sensitivity may suggest hypothyroidism, thyroid 131I rate can be reduced, normal or elevated, no For the differential diagnosis, the most powerful diagnosis is that after taking too much iodine, it causes goiter or hypothyroidism. After stopping iodine, the thyroid size and function return to normal. Most patients have positive thyroid antibodies, indicating that these patients have potential Chronic lymphocytic thyroiditis, or underlying thyroid dysfunction, is sensitive to excess iodine.
The incidence of hypothyroidism-induced hypothyroidism is unclear. Women are more likely than men to have hypothyroidism. From months to years, hyperiodine-induced hypothyroidism is mostly reversible, and iodine is relieved. After inhibition of synthesis and release, most of the thyroid function returned to normal in 3 weeks, or reached normal through compensatory effects.
Symptom
Symptoms of high iodine goiter common symptoms goiter, loss of appetite
1. Goiter: more diffuse, compared with low-iodine benign tough texture, palpation is easier to distinguish with low-iodine goiter, neonatal high-iodine goiter can compress the trachea, and even suffocation.
2. Most of the reported serum T3, T4, TSH is normal, there are also reports of low T4, high TSH, hypothyroidism or subclinical hypothyroidism, but in most people with high iodine ill, including patients with hyperthyroidism, Most of the thyroid function is normal.
3. The iodine absorption rate of thyroid gland in patients with high iodine goiter decreased for 24 hours, generally less than 10%.
4. In the water-borne high-iodine goiter disease area, it has been reported that in the absence of any intervention measures, childhood high-iodine goiter has more self-resolved after entering adulthood, indicating that people have higher intake of high iodine. Strong tolerance.
5. Long-term high iodine intake may have enhanced changes in the autoimmune process, such as: the emergence of autoimmune antibodies, autoimmune diseases or thyroid autoimmune diseases, the incidence of thyroid cancer (mainly papillary cancer), In 1980, Shandong reported for the first time that the incidence of hyperthyroidism in the high-iodine ward was 4.98 times that of the normal control area. In addition, Fang Weitang reported that 8 of 103 patients with high-iodine goiter had hyperthyroidism, but there were also different reports, such as Suzuki in Japan in 1965. No patients with hyperthyroidism were found in Hokkaido.
High iodine and Hashimoto's thyroiditis: In China, it has been observed that patients with hyperthyroidism and hyperthyroidism have higher TGAb and TPOAb than those in the iodine-prone area. Boyages et al. did not find high-iodine goiter in Shanxi province. There is any association with Hashimoto's thyroiditis.
6. High iodine and intellectual development: Since 1980, there have been reports on the measurement of children's intelligence level in high iodine areas. The results are inconsistent. Some scholars have observed that high iodine causes children's IQ level to decline, while others have not observed. High iodine has an impact on children's IQ. Different scholars have different evaluations on the impact of high iodine on children's IQ. There are many reasons for the inconsistent results of high iodine on IQ: the method of intelligence measurement is different (Ada Research-Tanzhongbi scale, China) Intra-scale scale, Raven scale, Wechschildren's scale, etc.; non-uniformity of high iodine area, inconsistent (for high iodine defined urinary iodine median between 500 ~ 3900g / L); control area selection The difference (if the author chooses the low iodine area as a control); the iodine nutritional status of the high iodine area and the control area are different, etc., Zhao Jinkou et al. will average the IQ and low IQ ratio among the authors' findings (IQ<70) ) With the urinary iodine median as a scatter plot, it has not been seen that the average IQ decreases with increasing urinary iodine levels, and the IQ ratio (IQ<70= also does not increase significantly with increasing urinary iodine levels).
Although the current findings do not provide a positive or negative answer to whether high iodine affects mental development, most convincing investigations suggest that high iodine has little effect on mental development, and at least there is not enough evidence to prove high iodine. It can cause brain development; in addition, there are no reports of cretinism in the high iodine area currently seen in the world.
Most of the current domestic animal experimental data suggest that high iodine has an impact on mental development, and can cause different degrees of brain development, which is inconsistent with epidemiological data, probably due to the high iodine diet iodine content used in animal experiments. High, ten times to hundreds of times higher than the normal requirement (close to the poisoning dose), greatly exceeding the iodine content of the daily diet of experimental animals. In the epidemiological survey of the population, the human body's iodine intake could not reach the experimental animals. The intake of unit weight, so the results of animal experiments are difficult to apply to humans, animal experiments also suggest that animals of different species do not accumulate high levels of iodine in the thyroid gland, it is difficult to form high iodine goiter; In mice, long-term high iodine can cause hyperiodative goiter, but the individual differences are large, not all mice can form a typical goiter.
Examine
Examination of high iodine goiter
1. Serum T3, T4, TSH examination results are normal, or T4 value is low, TSH value is high.
2. The thyroid function is normal.
3. Thyroid absorption 131I rate determination: thyroid absorption 131I rate decreased, generally less than 10%.
4. Potassium perchlorate excretion test is positive.
5. Determination of urinary iodine: urinary iodine excretion increased, often greater than 800g / g · Cr.
Diagnosis
Diagnosis and differentiation of high iodine goiter
Diagnostic criteria
The patient lives or lives in a high iodine area, with enlarged thyroid gland and hard texture (can perform thyroid biopsy if necessary); urinary iodine greater than 800 g/L; low iodine absorption rate (generally less than 10% at 24 h); clear high iodine History of intake; and can rule out goiter caused by other causes; it can be diagnosed as hyperiodized goiter.
1. The first is thyroid enlargement, generally diffuse enlargement, multi-line I ~ II degree, III degree is rare, the two sides of the leaves can vary in size, the surface is relatively smooth, the texture is tough, generally no noise, no tremor, knot The type of the joint, the mixed type is rare, and rarely causes the symptoms of compression of the trachea.
2. Neonatal hyperiodated goiter can compress the trachea and even suffocate and die.
3. Some patients may have hypothyroidism, such as cold, loss of appetite, constipation, and even some patients with mucinous edema.
4. Laboratory examination: high urinary iodine, often >800g / L creatinine, thyroid 131I rate is low, 24h 131I rate is often <15%, or even too low, perchlorate release test is often positive, plasma inorganic iodine and The iodine content in the thyroid is significantly increased, basal metabolism, blood cholesterol, serum T3, T4 and TSH are often in the normal range, but T4 can be low, even lower than normal, T3 can be high, even higher than normal, TSH can be higher than Normal, subclinical hypothyroidism, individual clinical hypothyroidism or hyperthyroidism.
Differential diagnosis
The diagnosis of high iodine goiter depends on the history and epidemic area combined with clinical symptoms and laboratory tests. It can be used for definite diagnosis. It needs to be differentiated from other thyroid diseases, hyperthyroidism, hypothyroidism, nodular goiter, and Hashimoto's thyroiditis. Most of the goiters are diffuse, and the quality is tough compared with low-iodine hyperthyroidism. The palpation and B-ultrasound are easy to identify.
