A breastfeeding infant, screened for congenital hypothyroidism, is found to have low levels of thyroxine (T4) and high levels of thyroid stimulating hormone (TSH). Which is the best explanation for this finding?
The TSH is high because of the low production of T4 by the thyroid.
The thyroxine level is low because the TSH level is high.
The thyroid gland does not produce normal levels of thyroxine for several weeks after birth.
High thyroxine levels normally occur in breastfeeding infants.
The Correct Answer is A
In a normal infant, T4 levels increase after birth due to stimulation by TSH from the pituitary gland. In this case, the T4 level is low and the TSH level is high, indicating that the thyroid gland is not producing enough T4 in response to TSH stimulation. This suggests that the infant may have congenital hypothyroidism, which requires prompt treatment to prevent developmental delays and other complications.
The low T4 level is not a direct cause of the high TSH level; rather, the high TSH level is a compensatory mechanism to increase T4 production. It is not normal for a breastfeeding infant to have high thyroxine levels. While the thyroid gland may take a few weeks to reach normal function after birth, the persistent low T4 and high TSH levels in this infant suggest a more serious issue.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
The nurse should prepare the mother for a sweat-chloride test to screen for cystic fibrosis (CF). A sweat- chloride test measures the amount of chloride in the sweat and is used to diagnose CF. CF is a genetic disorder that can cause the body to produce thick, sticky mucus that can clog the lungs and pancreas. One of the symptoms of CF is salty-tasting skin due to an increased amount of salt in the sweat. The other options (B, C, and D) are not standard diagnostic tests for screening for CF.
Correct Answer is D
Explanation
A. Many infants with congenital heart defects exhibit audible murmurs due to turbulent blood flow through abnormal openings or stenotic valves. While a murmur is a diagnostic hallmark of the condition, it is often an expected finding and does not necessarily indicate acute physiological deterioration. The nurse must document the murmur, but it is rarely the most urgent finding to report.
B. A heart rate of 162 beats/minute in an infant is slightly elevated above the typical resting range but can be triggered by crying, feeding, or baseline cardiac stress from the defect. Although tachycardia requires close monitoring to ensure the infant is not entering a state of high-output failure, it is less critical than signs of fluid overload. It represents a compensatory mechanism rather than an immediate life-threatening complication.
C. Infants with cardiac defects often experience fatigue during feeding because of the high metabolic demand and decreased cardiac output. Poor suckling effort and inadequate oral intake are common symptoms of pediatric heart failure that lead to failure to thrive over time. While this finding is significant for long-term nutritional management, it does not suggest an acute, rapid shift in stability like sudden weight changes.
D. Rapid weight gain of 1 kg within 48 hours is the most critical finding because it indicates acute fluid volume excess and potential congestive heart failure. In an infant, such a significant increase is almost certainly due to fluid retention rather than nutritional growth. This clinical sign suggests that the heart is unable to manage the systemic or pulmonary circulation effectively, necessitating immediate medical intervention.
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