A 65-year-old male reports nausea, vomiting, and constipation after a total knee replacement. What electrolyte is likely altered in this patient?

In a patient who has undergone a total knee replacement and is experiencing nausea, vomiting, and constipation, the most likely altered electrolyte is hypercalcemia. Nausea and vomiting can lead to dehydration and the loss of electrolytes, but constipation is particularly relevant here as it can manifest in a patient with elevated calcium levels.

Hypercalcemia can occur postoperatively for various reasons, including immobility, which is common after surgery, and potential alterations in parathyroid hormone secretion. In addition, as the body utilizes calcium for various physiological functions, it may mobilize calcium from the bones, especially if the patient is unable to ambulate effectively post-surgery.

Nausea and vomiting are common symptoms associated with elevated serum calcium levels, as they can affect gastrointestinal function and lead to decreased bowel motility, contributing further to constipation.

While the other options represent electrolyte imbalances that can occur in different clinical contexts, they are less likely in the scenario presented. Hyperkalemia typically arises from renal dysfunction or acute tissue injury, which doesn’t directly align with the postoperative context here. Hypomagnesemia might also cause nausea but isn't as strongly correlated with constipation as hypercalcemia. Lastly, hyponatremia is generally associated with fluid retention