Subclinical (Asymptomatic) Hypothyroidism in Pregnancy

As of 2010, the American College of Obstetrics & Gynecology Bulletin to physicians has recommended that physicians not routinely screen for Hypothyroidism, a disease that affects 2-5% of the population according to some studies.  Reason being, it is not considered cost effective; spending so much money on screening that will only pick up what is considered to be just a few additional pregnant patients who have a disease that may not even effect pregnancy outcome.  This is a similar concept that the government is trying to implement by changing the initiation of routine Screening Mammograms to age 50 from age 40.  Small benefit at time of astronomical health care costs

We know that Symptomatic Hypothyroidism in pregnancy can cause mental retardation, miscarriage, and preterm delivery.  There is definite controversy as to the effect of Subclinical or Asymptomatic Hypothyroidism, it is defined by elevated Thyroid Stimulating Hormone (aka Thyrotropin), but normal Thyroid hormone levels such as Free T4.

Some studies have suggested that this condition during pregnancy can cause mental retardation, miscarriage, and preterm labor.  We know it does if you have symptomatic Hypothyroidism.  It is the policy of my office to screen each new or future pregnant woman for Hypothyroidism.  If Thyroid Stimulating Hormone (TSH) is elevated once we will repeat it, if again it is elevated it will be treated

Additional controversy revolves around what the goal TSH should be after starting thyroid supplementation.  I recommend aiming for the normal range outlined on your lab test result.  I typically send in a prescription for Synthroid 50 UG by mouth per day to be taken separate from other medications, specifically prenatal vitamins, calcium, and iron as this will effect absorption.

I recheck levels in 4 – 6 weeks to make sure you are getting an adequate dose.  Some clinicians have recommended being overly aggressive with your TSH levels, but studies show a normal TSH is not associated with adverse outcomes so why treat the subset of patients with Subclinical Hypothyroidism patients different from a patient with normal TSH results.  Dr. Weinstein

Medical City Frisco (972) 668-8300

Learn more about tests performed during pregnancy here.


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