A nurse is collecting a blood phenylketonuria (PKU) test for a newborn prior to discharge. The newborn's guardian asks the nurse what a positive PKU test would mean.
Which of the following statements should the nurse make?
A positive finding indicates the inability to metabolize galactose.
A positive finding indicates the infant will have a slow metabolism.
A positive finding indicates an inability to metabolize certain amino acids.
A positive finding indicates an increased risk for neurologic anomalies.
The Correct Answer is C
Choice A rationale
A positive phenylketonuria (PKU) test indicates an inability to metabolize the amino acid phenylalanine, not galactose. Galactosemia is a separate metabolic disorder characterized by the body's inability to break down galactose, a sugar found in milk. Both are inborn errors of metabolism, but their biochemical pathways and dietary interventions differ significantly.
Choice B rationale
A positive PKU test does not indicate a slow metabolism in general. Instead, it specifically points to a deficiency in the enzyme phenylalanine hydroxylase (PAH), which is necessary for converting phenylalanine into tyrosine. This enzymatic defect leads to an accumulation of phenylalanine in the blood and tissues, which can become neurotoxic if untreated.
Choice C rationale
A positive finding for phenylketonuria (PKU) signifies a genetic disorder where the body lacks or has insufficient amounts of the enzyme phenylalanine hydroxylase. This enzyme is crucial for metabolizing the essential amino acid phenylalanine into tyrosine. Without proper enzyme function, phenylalanine accumulates in the blood, leading to neurotoxic effects if a specialized diet is not initiated promptly.
Choice D rationale
A positive PKU finding, if left untreated, directly leads to severe intellectual disability and other neurological problems due to the accumulation of phenylalanine, which is toxic to the developing brain. Therefore, it indicates an increased risk for neurologic anomalies if the condition is not managed through a strict low-phenylalanine diet from early infancy. .
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is D
Explanation
Choice A rationale
Transient circumoral cyanosis, a bluish discoloration around the mouth, can be a normal finding in the immediate newborn period, especially during periods of crying or temperature instability. It is often related to immature peripheral circulation and typically resolves as the newborn's circulatory system adapts to extrauterine life, without requiring intervention.
Choice B rationale
Transient strabismus, or crossed eyes, is a common and normal finding in newborns due to immature neuromuscular control of eye movements. The newborn's eye muscles are still developing coordination, and occasional misalignment is expected. This usually resolves spontaneously by 3 to 4 months of age as vision matures.
Choice C rationale
Caput succedaneum, a localized soft tissue edema of the scalp, is a common finding in newborns after vaginal birth. It results from pressure on the presenting part of the head during labor. It crosses suture lines and typically resolves within a few days, representing a benign finding that does not require medical intervention.
Choice D rationale
Generalized petechiae, which are small, pinpoint hemorrhages, are an abnormal finding in a 1-hour-old newborn and warrant immediate reporting to the provider. While scattered petechiae over the presenting part may occur with a difficult delivery, generalized petechiae can indicate a coagulation disorder, infection, or other serious underlying pathological condition requiring prompt evaluation and intervention.
Correct Answer is A
Explanation
Choice A rationale
For clients prescribed methadone during pregnancy, breastfeeding is generally encouraged due to the benefits of breast milk for the infant. Methadone excretion into breast milk is minimal and not considered harmful, and it can help to reduce the severity of neonatal abstinence syndrome.
Choice B rationale
Methamphetamine use during pregnancy is associated with several adverse fetal outcomes, but fetal macrosomia (abnormally large baby) is not typically one of them. Instead, it is more commonly linked to intrauterine growth restriction, preterm birth, and small for gestational age infants due to vasoconstrictive effects.
Choice C rationale
For newborns experiencing neonatal abstinence syndrome due to prenatal substance exposure, environmental stimuli should be decreased, not increased. Reducing stimuli like bright lights, loud noises, and excessive handling helps to minimize agitation, irritability, and seizures in these vulnerable infants.
Choice D rationale
Increased head circumference is not an expected finding in a newborn with fetal alcohol syndrome (FAS). In fact, microcephaly (abnormally small head circumference) is a characteristic diagnostic criterion for FAS, reflecting the detrimental effects of alcohol on fetal brain development.
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