The mother of a 2-month-old infant is afraid of giving her child immunizations and asks why they are necessary. The nurse's best response would be:

Choice A reason: Sodium excess (hypernatremia) is a condition in which the blood sodium level is too high. It can cause symptoms such as thirst, dry mouth, confusion, seizures, and coma. Sodium excess is usually caused by excessive intake of salt or fluids, or by loss of water due to diabetes insipidus, burns, or sweating. Sodium excess does not cause poor skin turgor, weight loss, or irritability.

Choice B reason: Calcium excess (hypercalcemia) is a condition in which the blood calcium level is too high. It can cause symptoms such as nausea, vomiting, constipation, abdominal pain, muscle weakness, bone pain, kidney stones, and cardiac arrhythmias. Calcium excess is usually caused by hyperparathyroidism, malignancy, vitamin D overdose, or prolonged immobilization. Calcium excess does not cause poor skin turgor, weight loss, or tachycardia.

Choice C reason: Overhydration (hypervolemia) is a condition in which the body has too much fluid. It can cause symptoms such as edema, weight gain, shortness of breath, cough, and hypertension. Overhydration is usually caused by excessive intake of fluids, or by retention of fluids due to heart failure, kidney failure, or liver cirrhosis. Overhydration does not cause poor skin turgor, weight loss, or irritability.

Choice D reason: Dehydration is a condition in which the body does not have enough fluid. It can cause symptoms such as poor skin turgor, weight loss, irritability, tachycardia, tachypnea, sunken eyes, dry mouth, and decreased urine output. Dehydration is usually caused by loss of fluids due to vomiting, diarrhea, fever, or excessive sweating. Dehydration is the most likely diagnosis for the infant based on the data.

Choice A reason: Surgery is the definitive treatment for hypertrophic pyloric stenosis, which is a condition in which the muscle of the pylorus (the outlet of the stomach) becomes thickened and blocks the passage of food into the small intestine. The surgery, called pyloromyotomy, involves cutting the muscle to widen the opening and allow food to pass through. The surgery is usually done laparoscopically, with small incisions and a camera, and has a high success rate and low complication rate¹.

Choice B reason: Dietary restrictions are not required throughout childhood for infants with hypertrophic pyloric stenosis. After the surgery, the infant can resume normal feeding, usually within a few hours or days. The infant may have some vomiting or spitting up for a short period, but this usually resolves without any special diet.

Choice C reason: Slow feeding is not a necessary intervention for infants with hypertrophic pyloric stenosis. Slow feeding may help reduce the amount of vomiting, but it does not address the underlying problem of the pyloric obstruction. Slow feeding may also cause the infant to become frustrated, hungry, or tired. The infant should be fed according to his or her appetite and cues, and burped frequently to prevent air swallowing.

Choice D reason: Chromosomal mutation is not the cause of hypertrophic pyloric stenosis. The exact cause of this condition is unknown, but it is likely influenced by both genetic and environmental factors. Some studies have found an association between hypertrophic pyloric stenosis and certain genes, but no single gene mutation has been identified as the cause. Other risk factors include being male, firstborn, premature, exposed to certain antibiotics, or having a family history of the condition².