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
Wound infection following circumcision typically presents with signs such as erythema (redness), localized warmth, purulent drainage, and swelling, often accompanied by fever. Yellow exudate alone, without these other inflammatory indicators, does not align with the typical presentation of a bacterial infection.
Choice B rationale
Ulceration would manifest as an open sore or a break in the skin integrity, often with raw, exposed tissue. The yellow exudate covering the glans, if it represents a healing process, is a protective layer and not indicative of tissue breakdown or an open ulcer.
Choice C rationale
Exposure to urine does not typically result in a uniform yellow exudate covering the glans. While prolonged urine exposure can lead to skin irritation or maceration, the described finding is a distinct physiological response associated with tissue repair rather than simple urinary contact.
Choice D rationale
The formation of a yellow exudate or "scab" on the glans penis is a normal physiological response during the healing process after circumcision. This fibrinogen-rich layer acts as a protective barrier, preventing infection and facilitating re-epithelialization of the wound, and it typically resolves within 7-10 days.
Correct Answer is D
Explanation
Choice A rationale
Droplet precautions are implemented for pathogens transmitted via large respiratory droplets, such as influenza or meningococcal disease. Herpes simplex virus is typically transmitted through direct contact with lesions or secretions, not primarily through airborne droplets. Therefore, instituting droplet precautions would not be the most scientifically appropriate measure for preventing HSV transmission in this context.
Choice B rationale
Ceftriaxone sodium is a broad-spectrum cephalosporin antibiotic used to treat bacterial infections, such as gonorrhea or bacterial meningitis. Herpes simplex virus is a viral infection, and antibiotics are ineffective against viruses. Administering ceftriaxone would not address the underlying viral etiology of the newborn's exposure to HSV.
Choice C rationale
Bottle-feeding the newborn is not a primary intervention to prevent transmission of HSV from a mother with active genital herpes to a newborn. HSV is transmitted through direct contact during passage through the birth canal. Breastfeeding is generally considered safe for mothers with HSV unless there are active lesions on the breast.
Choice D rationale
Obtaining surface cultures from the newborn is a crucial diagnostic step to confirm the presence of HSV infection in a neonate exposed during birth. This allows for timely initiation of antiviral therapy, such as acyclovir, which is essential to prevent systemic dissemination and severe complications like encephalitis, which can be life-threatening in newborns.
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