In psychogenic polydipsia, which electrolyte abnormality is typically observed?

In psychogenic polydipsia, which electrolyte abnormality is typically observed?

• A. Hypernatremia
• B. Hyperkalemia
• C. Hypokalemia
• D. Hyponatremia

Answer: (D)

The key idea is that psychogenic polydipsia causes dilution of the blood from drinking large amounts of water. When someone drinks so much water, the kidneys’ ability to excrete free water is overwhelmed, leading to a fall in serum sodium—hyponatremia. This dilutional hyponatremia is the typical electrolyte abnormality seen. Hypernatremia would suggest dehydration or excessive water loss, while potassium abnormalities aren’t the hallmark findings here. Clinically, hyponatremia from polydipsia can range from mild symptoms to confusion or seizures, depending on how low the sodium level is.

The key idea is that psychogenic polydipsia causes dilution of the blood from drinking large amounts of water. When someone drinks so much water, the kidneys’ ability to excrete free water is overwhelmed, leading to a fall in serum sodium—hyponatremia. This dilutional hyponatremia is the typical electrolyte abnormality seen. Hypernatremia would suggest dehydration or excessive water loss, while potassium abnormalities aren’t the hallmark findings here. Clinically, hyponatremia from polydipsia can range from mild symptoms to confusion or seizures, depending on how low the sodium level is.