How is low molecular weight heparin primarily excreted, and in which patients should dosing be considered carefully?

How is low molecular weight heparin primarily excreted, and in which patients should dosing be considered carefully?

• A. Through the kidneys; should be avoided in those with kidney failure
• B. Metabolized by the liver
• C. Excreted in bile
• D. Filtered by the lungs

Answer: (A)

Low molecular weight heparin is cleared mainly by the kidneys. Because renal excretion is the predominant route, reduced kidney function allows the drug to accumulate, raising the risk of bleeding. Therefore dosing must be carefully considered in patients with kidney failure or significant renal impairment. The other routes—hepatic metabolism, biliary excretion, or pulmonary filtration—do not play the primary role in LMWH clearance, which is why those options are not appropriate. In patients with severe renal impairment, clinicians often adjust or avoid LMWH and consider alternatives that don’t accumulate as readily in the setting of kidney dysfunction.