Which labs should be checked before giving digoxin?

• A. BUN and Creatinine
• B. CBC and Platelets
• C. Liver Enzymes
• D. Electrolytes Only

Answer: (B)

Digoxin safety hinges on kidney function and electrolyte balance because the drug is cleared by the kidneys and its action is highly sensitive to electrolyte levels. Checking renal function tells you whether the dose needs adjustment to avoid accumulation, while electrolyte status—especially potassium and magnesium—affects how strongly digoxin interacts with the Na+/K+ ATPase pump. Low potassium (hypokalemia) can make digoxin toxicity more likely, and abnormal magnesium or calcium levels can also influence the risk and presentation of toxicity.

Because of this, the most relevant labs to check before starting digoxin are renal function tests (creatinine and BUN) and electrolyte levels. CBC and platelets, liver enzymes, or simply “electrolytes only” do not provide the same crucial information about digoxin clearance and toxicity risk.