In early pregnancy, due to heavy early pregnancy reaction, easy strain and emotional tension, coupled with changes in hormone levels in the body, some pregnant women may have irritability and irritable personality changes, but they generally rarely reach the level of irritability. If you experience impatience, anxiety, excessive sweating, panic attacks and other signs of accelerated metabolism after pregnancy, you should first rule out hyperthyroidism (hyperthyroidism). Thyroid function tests include serum TSH (thyroid stimulating hormone), FT4 (free T4), and TPOAb (thyroid peroxidase antibody) measurements. If serum TSH is <0.1miu/L, FT4 is normal or mildly elevated, and TPOAb is usually negative, it indicates subclinical hyperthyroidism, which is commonly caused by transient hyperthyroidism in pregnancy. This is related to the increased production of HCG (human chorionic gonadotropin) in pregnant women, which over-stimulates the production of thyroid hormones. If TSH is less than 0.1miu/L, FT4 is significantly elevated and TPOAb is positive, it indicates clinical hyperthyroidism, which is commonly caused by Graves' disease; clinical hyperthyroidism that is mild or can be controlled by treatment has little effect on pregnancy. The risk of miscarriage, preterm delivery, stillbirth, low birth weight baby, hypertension during pregnancy, thyroid crisis and maternal congestive heart failure increases with more severe or uncontrollable clinical hyperthyroidism. For treatment, propylthiouracil (PTU) is preferred for clinical hyperthyroidism in early pregnancy, and methimazole (MMI) is preferred in mid- to late-pregnancy and during lactation. In conclusion, the appearance of irritability in early pregnancy, with significant changes compared to non-pregnancy, should be highly alert to the possibility of hyperthyroidism.