A mother brings her 2-month-old to the well-baby clinic.

She mentions that when she kisses her baby, the infant’s skin tastes salty.

What standard diagnostic test should the nurse prepare the mother for to screen for cystic fibrosis (CF)?

Choice A rationale
Enalapril is an angiotensin-converting enzyme (ACE) inhibitor commonly used in the treatment of heart failure. It works by widening blood vessels, which reduces the workload of the heart and helps keep heart failure from getting worse. In the given scenario, there is no specific indication to hold Enalapril based on the infant’s vital signs.
Choice B rationale
Digoxin is a medication that can help the heart beat stronger with a more regular rhythm. However, it is important to monitor the patient’s heart rate when administering Digoxin, as it can lower the heart rate. In this case, the infant’s apical pulse is 88 beats/minute, which is lower than the normal range for an eight-month-old infant (normal range: 100-160 beats/minute). Therefore, the nurse should hold the Digoxin and inform the healthcare provider.
Choice C rationale
Furosemide is a diuretic that helps the kidneys get rid of extra fluid that may build up in the body. It is often used in the treatment of heart failure to relieve symptoms such as fluid retention. In the given scenario, there is no specific indication to hold Furosemide based on the infant’s vital signs.
Choice D rationale
Hydralazine is a medication used to treat high blood pressure. It works by relaxing and widening blood vessels so blood can flow more easily. In the given scenario, there is no specific indication to hold Hydralazine based on the infant’s vital signs.

Choice A rationale
While it’s true that TSH levels can influence thyroxine levels, this statement is misleading. High TSH levels do not cause low thyroxine levels. Instead, the pituitary gland produces more TSH when thyroxine levels are low in an attempt to stimulate the thyroid gland to produce more thyroxine.
Choice B rationale
Thyroxine levels in breastfeeding infants should be within the normal range. High thyroxine levels are not typical and could indicate a problem with the infant’s thyroid gland.
Choice C rationale
This statement is incorrect. The thyroid gland begins producing thyroxine before birth, and levels should be within the normal range shortly after birth.
Choice D rationale
This is the correct explanation. In congenital hypothyroidism, the thyroid gland does not produce enough thyroxine, leading to high levels of TSH. The pituitary gland produces more TSH in an attempt to stimulate the thyroid gland to produce more thyroxine.