Today we had an excellent case led by Dr. McGee of a patient with B-symptoms of unknown etiology, with some great varied discussion points. One of them was regarding digoxin toxicity, check it out!
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Digoxin Toxicity
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Who is at risk? Older age, reduced BMI, and acute or chronic renal insufficiency.
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Clinical s/sx; Arrhythmias! (any kind, however often PVCs are the early sign), GI symptoms (nausea, vomiting), and neurologic (confusion, lethargy)
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Diagnosis; Order a serum digoxin level (normal is 0.5-0.8 ng/mL), serum potassium, BUN, Cr, and EKG. Note; the serum digoxin level may not necessarily correlate with toxicity, however is helpful if you are concerned with the patient’s s/sx.
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What is the d/dx? B-blocker, Calcium channel blocker and alpha-antagonist poisoning may resemble digoxin toxicity with bradycardia and hypotension! How would you differentiate these? Firstly with elevated digoxin level, second, calcium channel blockers often results in hyperglycemia, and alpha-antagonist poisoning has more CNS and respiratory depression.
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Treatment; Firstly, manage life-threatening arrhythmias! Give digoxin-specific antibody fragments (Fab), especially if life threatening arrhythmias, hyperkalemia >5, or evidence of end-organ dysfunction.
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NOTE: Do not use potassium-lowering agents in hyperkalemia due to digoxin toxicity as giving Fab will regenerate Na/K ATPases which pump K back into cells. Giving potassium-lowering agents may result in dangerous hyPOkalemia.
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