What is the normal range of serum sodium in adults?

Choice A reason: This is incorrect because polyuria is a sign of hyponatremia, not hypernatremia. Polyuria is the excessive production of urine, which can cause fluid loss and sodium dilution.

Choice B reason: This is correct because dry mucous membranes are a sign of hypernatremia. Dry mucous membranes are caused by dehydration, which can occur in hypernatremia due to fluid shifting from the intracellular to the extracellular space.

Choice C reason: This is incorrect because diarrhea is a sign of hyponatremia, not hypernatremia. Diarrhea is the frequent and watery passage of stool, which can cause fluid and electrolyte loss.

Choice D reason: This is incorrect because intense thirst is a sign of both hyponatremia and hypernatremia. Intense thirst is a result of the body's attempt to restore fluid balance and osmolarity.

Choice E reason: This is incorrect because vomiting is a sign of both hyponatremia and hypernatremia. Vomiting is a reflex action that expels the contents of the stomach, which can cause fluid and electrolyte loss or imbalance.

Choice A reason: 60 mL of urine in a 2-hour period is not very concerning for a nurse, as it is within the normal range of urine output. The average urine output for an adult is about 1 to 2 L per day, or 40 to 80 mL per hour¹.

Choice B reason: 720 mL of urine in a 24-hour period is slightly below the normal range, but not alarming. It may indicate mild dehydration or reduced fluid intake, but it is not a sign of fluid volume excess or kidney failure¹.

Choice C reason: 600 mL of urine in a 10-hour period is also within the normal range of urine output, and does not indicate any problem with fluid balance or renal function¹.

Choice D reason: 100 mL of urine in a 5-hour period is the most concerning for a nurse, as it indicates oliguria, or abnormally low urine output. Oliguria is defined as urine output less than 400 mL per day, or less than 20 mL per hour². It may be caused by acute or chronic kidney injury, urinary obstruction, shock, dehydration, or fluid volume excess². Oliguria can lead to fluid overload, electrolyte imbalance, acidosis, and uremia, and requires immediate medical attention².