Thyroid function tests (TFTs) in hypothyroid women during pregnancy

TSH levels and free T4 levels should be measured to determine the thyroid status during pregnancy.

Ideally the following sequence of TFT should be performed in the hypothyroid woman during pregnancy:

• before conception if possible
• at time of diagnosis of pregnancy
• at antenatal booking
• at least once in second and third trimesters and again after delivery (e.g. 2-4 weeks post-partum)
• the newly diagnosed hypothyroid patient will need to be tested frequently (e.g. every 4-6 weeks) until stabilized (1).

TFT should be done in pregnant women with:

• type-1 diabetes
• previous history of thyroid disease
• current thyroid disease
• family history of thyroid disease
• goitre
• symptoms of hypothyroidism (1)

Reference:

• 1. Association for Clinical Biochemistry (ACB), British Thyroid Association (BTA), British Thyroid Foundation (BTF) 2006.UK guidelines for the use of thyroid function tests