What abnormal lab finding indicates hypothyroidism in pregnancy?

The abnormal lab finding that indicates hypothyroidism in pregnancy is characterized by increased TSH levels coupled with decreased FT4. This is consistent with the physiological changes that occur during pregnancy.

During hypothyroidism, the thyroid gland does not produce enough thyroid hormones (FT4 being one of them). In response, the pituitary gland compensates by producing more thyroid-stimulating hormone (TSH) in an attempt to stimulate the thyroid to produce adequate levels of hormones. Therefore, in a pregnant woman with hypothyroidism, the expected lab results would show elevated TSH levels, indicating that the pituitary gland is working harder to increase low thyroid hormone levels, while FT4 levels would be low due to underproduction by the thyroid.

This interpretation is vital for diagnosing and managing thyroid disorders during pregnancy, as untreated hypothyroidism can lead to complications for both the mother and the fetus. Understanding these lab values helps in making appropriate treatment decisions and monitoring the health of the mother and baby.

In contrast, other combinations of hormone levels would suggest different states of thyroid function or even be within normal limits, such as normal TSH and FT4 levels indicating a euthyroid state, or decreased TSH levels signaling hyperthyroidism rather than hypothyroidism.