What is a common complication that can arise from untreated dehydration?

Untreated dehydration can lead to kidney failure because the kidneys require a sufficient amount of fluids to effectively filter waste products from the blood and maintain balance within the body. When the body becomes dehydrated, the blood volume decreases, making it harder for the kidneys to function properly. This condition can lead to acute kidney injury, where the kidneys may be unable to filter waste products or regulate electrolytes effectively. Prolonged dehydration can cause the kidneys to suffer permanent damage, which may result in chronic kidney disease or failure over time.

The other options—such as hypertension, diabetes mellitus, and heart attack—are less directly associated with the immediate effects of untreated dehydration. While dehydration can have complicated impacts on cardiovascular health and blood pressure, the direct and immediate consequence of severe dehydration is more appropriately linked to the kidneys. Therefore, kidney failure is the most relevant complication in the context of untreated dehydration.