Hypothyroidism in pregnancy
Diagnosis and treatment norms of hypothyroidism in pregnancy
I. To diagnose abnormal thyroid function in pregnancy, reference values for serum thyroid function indicators should be established for the unit or region
Second, the normal values recommended by the American Academy of Thyroid Diseases (ATA) in 2011 can be applied at present
Early TSH 0.1~2.5 mIU/L
Mid-stage TSH 0.2~3.0mIU/L
Late TSH 0.3~3.0mIU/L
Third, people at high risk of thyroid disease.
1. History of thyroid disease, history of thyroid surgery, history of iodine 131 treatment
2. Family history of thyroid disease
3. Enlarged thyroid gland
4. Positive thyroid autoantibodies
5. Symptoms and clinical manifestations of hypothyroidism or hypothyroidism
6. Type I diabetes mellitus
7. Other autoimmune diseases
8. Infertile women
9. Previous head and neck radiotherapy
10. obesity (BMI > 40)
11. Women over 30 years of age
12. Women taking amiodarone therapy, recently exposed to iodine contrast media
13. History of miscarriage or premature birth
14.Women living in iodine deficient areas
IV. Clinical hypothyroidism
Hazards of clinical hypothyroidism during pregnancy.
Mother: miscarriage, hypertensive disorders during pregnancy, placental abruption, cesarean delivery, postpartum hemorrhage
Fetus: preterm birth, low birth weight, neonatal respiratory distress, abnormal neuropsychiatric development, fetal death
1. The diagnostic criteria for clinical hypothyroidism in pregnancy are serum TSH > upper limit of reference value in pregnancy and FT4 < lower limit of reference value in pregnancy.
2. Early pregnancy women with TSH>10 mIU/L, regardless of whether FT4 is reduced, are treated as clinical hypothyroidism
3.Serum TSH treatment target.
Early TSH 0.1~2.5 mIU/L
Mid-stage TSH 0.2~3.0mIU/L
Late TSH 0.3~3.0mIU/L
Once clinical hypothyroidism is confirmed, start treatment immediately to reach the standard as soon as possible.
4. Women with clinical hypothyroidism who are planning to get pregnant need to control TSH to <2.5 mIU/L before pregnancy.
5. L-T4 therapy is preferred for hypothyroidism in pregnancy. The complete replacement dose of clinical hypothyroidism in pregnancy can reach 2-4ug/kg. d, and the starting dose of L-T4 is 50-100ug/d.
6. The dose of L-T4 needs to be increased by about 25-30% in women with clinical hypothyroidism after pregnancy, and the dose should be adjusted according to the serum TSH target.
After pregnancy, thyroid function, including TSH, should be monitored every 4 weeks from 1 to 20 weeks of pregnancy and once from 26 to 32 weeks of pregnancy.
8. Postpartum LT4 dose should be reduced to pre-pregnancy level in pregnant women with clinical hypothyroidism, and serum TSH level should be rechecked 6 weeks after delivery to adjust LT4 dose
V. Subclinical hypothyroidism (SCH)
1. Diagnostic criteria for subclinical hypothyroidism: serum TSH > upper limit of reference value in pregnancy, FT4 within normal range.
2. SCH in pregnancy increases the risk of adverse pregnancy outcomes and impairment of offspring intellectual development, but treatment is neither opposed nor recommended for TPOAb-negative individuals due to insufficient evidence.
3. LT4 treatment is recommended for pregnant women with TPOAb-positive SCH.
4. The treatment, treatment goals and monitoring frequency of subclinical hypothyroidism in pregnancy are the same as those of clinical hypothyroidism, and different doses of L-T4 can be given according to the degree of TSH elevation
5. The starting dose of L-T4 is chosen according to the degree of TSH elevation.
L-T4 requirements can be estimated in 3 ways.
(i) 30% to 50% increase in L-T4 requirement during pregnancy.
(ii) Calculating the requirement on a per kilogram of body weight basis, i.e., 2.0 to 2.4 μg/kg per day (1.6 to 1.8 μg/kg per day in non-pregnancy).
(iii) The supplemental dose of L-T4 is judged according to the measured serum TSH level. For example, serum
TSH 5 to 10 mU/L, supplementation with L-T4 25 to 50 μg/d.
TSH 10-20mU/L, supplementation with L-T4 50-75μg/d.
TSH >20mU/L, supplement L-T4 75-100μg/d.
Recommended therapeutic target values for serum TSH in pregnancy <2.5 mU/L in T1 and <3.0 mU/L in T2 and T3.