NCLEX Heart Failure Practice Test

Loop diuretics cause strong diuresis by blocking the Na-K-2Cl transporter in the thick ascending limb of the loop of Henle. This stops reabsorption of sodium, chloride, potassium, and calcium, so more of these minerals are lost in the urine and fluid is drawn out of the body. The most important adverse effects to monitor are electrolyte disturbances, especially low potassium, along with signs of volume depletion like dehydration and orthostatic hypotension. Hypokalemia can lead to dangerous cardiac rhythms, so regular checks of electrolytes and careful assessment of hydration status are essential.

Hyperkalemia isn’t typical with loop diuretics because these drugs promote potassium loss rather than retention. Hypercalcemia is also unlikely since calcium is excreted more with loop diuretics. Hyponatremia can occur, but the hallmark concern tied to loop diuretics is the combination of potassium loss and volume depletion that requires close monitoring.