A pediatric nurse is assessing a 10-year-old girl with signs of anorexia nervosa.
Which physical assessment finding would support the diagnosis?

Choice A rationale

Vitamin K's primary physiological role is in coagulation, not in enhancing the immune system to prevent healthcare-associated infections. Newborns receive vitamin K to prevent bleeding disorders, not to boost their immunity against bacterial or viral pathogens. Infection control practices are crucial for preventing healthcare-associated infections, not vitamin K administration.

Choice B rationale

Vitamin K is essential for the synthesis of clotting factors II, VII, IX, and X in the liver. Newborns have immature livers and limited vitamin K stores, making them susceptible to Vitamin K Deficiency Bleeding (VKDB), also known as hemorrhagic disease of the newborn. Administering vitamin K prophylactically decreases this risk, preventing potentially life-threatening bleeding episodes.

Choice C rationale

Vitamin K is administered to prevent hemorrhagic disorders and has no known direct impact on reducing complications specifically from the Hepatitis B vaccine. The Hepatitis B vaccine stimulates active immunity against the Hepatitis B virus. Any complications from vaccination are unrelated to the infant's vitamin K status or coagulation cascade.

Choice D rationale

Jaundice in newborns is primarily caused by elevated unconjugated bilirubin levels due to physiological processes like increased red blood cell breakdown and immature liver conjugation. Vitamin K does not play a role in bilirubin metabolism or excretion, and therefore, it does not decrease the newborn's risk of jaundice. Phototherapy or other interventions are used for hyperbilirubinemia.

Choice A rationale

Low potassium (hypokalemia) and ECG rhythm changes, such as QT prolongation or arrhythmias, are critical and life-threatening complications of bulimia nervosa due to fluid and electrolyte imbalances from purging behaviors. Hypokalemia can directly impair cardiac function, necessitating immediate medical intervention to prevent fatal arrhythmias.

Choice B rationale

Erosion of dental enamel and constant vomiting are chronic manifestations of bulimia nervosa. While they indicate ongoing disordered eating and require dental intervention, they are not acutely life-threatening and do not represent the same level of immediate physiological instability as severe electrolyte imbalances affecting cardiac function.

Choice C rationale

Menstrual irregularities, including amenorrhea, are common in individuals with bulimia nervosa due to hormonal disruptions from malnutrition and stress. While indicative of chronic health impact, they are not an immediate life-threatening concern requiring emergency intervention compared to acute cardiac complications.

Choice D rationale

Calluses on knuckles (Russell's sign) and skin breakdown are physical signs of repeated self-induced vomiting. These are chronic cutaneous manifestations reflecting the mechanical trauma from purging. While they require attention, they are not acute physiological emergencies demanding immediate intervention.