Hypothyroidism is one of the causes of recurrent miscarriage, accounting for about 10% of recurrent miscarriages. It is a problem that is easily overlooked when investigating the cause.
Hypothyroidism (hypothyroidism) is a generalized hypometabolic syndrome caused by decreased synthesis and secretion of thyroid hormones or insufficient tissue utilization. If hypothyroidism begins in the fetal or neonatal period, it is called Cretinism; in children before sexual development, it is called juvenile hypothyroidism; in adults, it is called adult hypothyroidism.
I. Classification
Classification according to the site of lesion occurrence.
1, primary hypothyroidism: hypothyroidism caused by the lesion of the thyroid gland itself is called primary hypothyroidism. It accounts for more than 95% of all hypothyroidism. Among the causes of primary hypothyroidism, autoimmunity, thyroid surgery and hyperthyroidism 131I treatment account for more than 90% of the three major causes.
2, central hypothyroidism: hypothyroidism due to hypothalamic and pituitary lesions caused by a decrease in the production and secretion of thyrotropin-releasing hormone (TRH) or thyroid stimulating hormone (TSH) is called central hypothyroidism. External pituitary irradiation, pituitary macroadenoma, craniopharyngioma and postpartum haemorrhage are the more common causes.
3.Thyroid hormone resistance syndrome: The syndrome caused by the impairment of the biological effect of thyroid hormone in peripheral tissues is called thyroid hormone resistance syndrome.
Classification according to the degree of hypothyroidism.
1. clinical hypothyroidism.
2, subclinical hypothyroidism.
Clinical manifestations
Symptoms are mainly based on reduced metabolic rate and decreased sympathetic excitability, and early patients with mild disease may have no specific symptoms. Typical patients have chills, fatigue, swelling of hands and feet, drowsiness, memory loss, low sweating, joint pain, weight gain, constipation, menstrual disorders in women, or excessive menstruation, infertility. Repeated miscarriage.
Physical examination
Typical patients may have dull expression, unresponsiveness, puffy face and/or eyelids, thick lips and large tongue, dry, rough skin, low skin temperature, puffiness, ginger skin on the palms of hands and feet, sparse and dry hair, prolonged Achilles tendon reflex, and slow pulse rate. In a few cases, anterior tibial mucinous edema is present. The disease may involve the heart with pericardial effusion and heart failure. In severe cases, mucus edema coma can occur.
Laboratory diagnosis
In primary hypothyroidism, serum TSH is increased and TT4 and FT4 are decreased. the level of increased TSH and decreased TT4 and FT4 correlates with the degree of the disease. Serum TT3 and FT3 are normal in the early stage and decreased in the late stage. Subclinical hypothyroidism has only increased TSH and normal TT4 and FT4.
Thyroid peroxidase antibody (TPOAb) and thyroglobulin antibody (TgAb) are the main indicators for the diagnosis of autoimmune thyroiditis (including Hashimoto’s thyroiditis and atrophic thyroiditis). If TPOAb is positive with an increased serum TSH level, it indicates that damage to thyroid cells has occurred. When TPOAb>50IU/ml and TgAb>40IU/ml at the initial visit, the incidence of clinical hypothyroidism and subclinical hypothyroidism increases significantly.
V. Treatment
Levothyroxine (L-T4, eugenol) is the main replacement therapy drug for this disease. Lifetime replacement is usually required. However, spontaneous remission of hypothyroidism due to Hashimoto’s thyroiditis has also been reported. The goal of treatment is the disappearance of clinical signs and symptoms of hypothyroidism and the maintenance of TSH, TT4, and FT4 values within normal limits. In hypothyroidism secondary to hypothalamus and pituitary, TSH should not be used as a therapeutic indicator, but the goal of treatment is to achieve normal range of serum TT4 and FT4.
The dose of treatment depends on the patient’s condition, age, weight and individual differences. The replacement dose of L-T4 in adult patients is 50-200 μg/day, with an average of 125 μg/day. The dose according to body weight is 1.6-1.8 μg/kg/day; children need a higher dose, about 2.0 μg/kg/day; elderly patients need a lower dose, about 1.0 μg/kg/day; the replacement dose in pregnancy needs to be increased by 30-50%; patients with postoperative thyroid cancer need high dose replacement, about 2.2 μg/kg/day, to control TSH at level needed to prevent tumor recurrence.
It is usually started at 25-50 μg/day orally once a day and increased by 25 μg every 1-2 weeks until the therapeutic goal is reached. The starting dose should be small and the dose should be adjusted slowly to prevent the induction and aggravation of heart disease in people suffering from ischemic heart disease. T4 has a half-life of 7 days, so it can be taken once a day in the morning. Thyroid tablets are a dry preparation of the thyroid gland of animals and are rarely used because of their unstable thyroid hormone content and high T3 content.
It usually takes 4-6 weeks to re-establish the balance of hypothalamic-pituitary-thyroid axis, so hormonal indicators are measured at 4-6 week intervals at the beginning of treatment. The L-T4 dose is then adjusted according to the test results until the target of treatment is reached. After the treatment target is reached, hormone indicators need to be rechecked every 6-12 months.