The nurse is collecting a heel-stick blood specimen for a neonatal screen, which includes thyroxine (T4) and thyroid- stimulating hormone (TSH) levels, prior to discharging a 2-day-old patient. When the parents ask why these tests are being conducted, which explanation should the nurse provide?

Choice A rationale The neonatal screening test, which includes thyroxine (T4) and thyroid-stimulating hormone (TSH) levels, is a routine blood test required by law to screen for metabolic deficiencies. This test helps diagnose thyroid conditions. T4 is a thyroid hormone, and too much or too little of it can indicate an issue with the thyroid. TSH is a hormone your pituitary gland makes. It stimulates your thyroid to produce T4 and T3 (triiodothyronine) hormones. A TSH test is the best way to initially assess thyroid function. In fact, T4 tests more accurately reflect thyroid function when combined with a TSH test. Measuring T4 levels might not be necessary in all thyroid conditions. Other names for a T4 test include: Free thyroxine, Total T4 concentration, Thyroxine screen, Free T4 concentration, Free T4 index (FTI)1. Choice B rationale While the T4 and TSH tests can help diagnose thyroid conditions, they are not specifically used to determine dosages for thyroid replacement therapy. The dosage of thyroid replacement therapy is usually determined by a healthcare provider based on the patient’s medical condition, weight, age, laboratory test results, and response to treatment. Choice C rationale The neonatal screening test is not specifically used for the early detection of intellectual disabilities. However, it is important to note that untreated congenital hypothyroidism can lead to intellectual disabilities. Therefore, early detection and treatment of hypothyroidism generally result in normal growth and development. Choice D rationale While these laboratory values can provide data about the thyroid function of the newborn, they do not directly provide data to anticipate delays in growth and development. However, untreated congenital hypothyroidism can lead to growth and developmental delays. Therefore, early detection and treatment of hypothyroidism generally result in normal growth and development.