Reversing the Impact of a Missing Hormone
Building on the discoveries that allowed mass screening for phenylketonuria (PKU), NICHD-supported researchers developed a similar screening method for congenital hypothyroidism (CH). CH is a metabolic condition that results from problems with the thyroid gland. The thyroid gland makes thyroid hormone (also called thyroxine), which the body uses to regulate many of its functions, including temperature and energy levels.
In most cases of CH, problems with the thyroid start in the womb. If the gland is missing, incomplete, or in the wrong place, the body does not produce enough thyroid hormone. Missing or low levels of the hormone lead to abnormal growth and development, as well as slower intellectual functioning. Simply providing thyroid hormone at normal levels can prevent the effects and health problems of CH.
During pregnancy, the mother's thyroid gland makes up for the problems with the fetus' thyroid gland by making enough thyroid hormone for normal development. But, after birth, low levels of thyroid hormone cause slow growth, especially in the brain. If undetected and untreated, CH causes intellectual disability that cannot be reversed.
The successes surrounding PKU research in the early 1960s offered hope that CH also could be detected in newborns and thereby allow for treatment to prevent its effects. Dr. Robert Guthrie had developed a simple, inexpensive test for PKU that used a drop of blood on filter paper, allowing mass screening, early detection, and early treatment. Building on this testing method, NICHD-supported researchers created a new screening technique that could reliably measure thyroid hormone and thyroid-stimulating hormone, the two main markers of CH. This reliable and inexpensive test allowed for mass screening of newborns.
Institute-supported studies on the screening test’s effectiveness showed that children with CH detected by the test and who received appropriate levels of thyroid hormone, had the same intellectual capabilities as their siblings who did not have the condition.
As a result of NICHD research, every state screens newborns for CH to detect it and begin treatment immediately, preventing the disabilities previously associated with the condition.