Indications for Digoxin Blood Level Monitoring

 

Indications for digoxin level monitoring:

(1) subtherapeutic response - one or more of the following:

(1a) no improvement or worsening of congestive heart failure

(1b) no improvement or worsening of atrial fibrillation or flutter

(1c) suspected noncompliance

(1d) concomitant use of an interacting drug: antacids, a kaolin and pectin combination (Kaopectate), neomycin, quinidine, amiodarone, spironolactone, nifedipine, cholestyramine, verapamil

(1e) suspected malabsorption

(2) suspected toxicity - one or both of the following:

(2a) appearance of arrhythmias suspected to be caused by digoxin (supraventricular tachycardia, atrioventricular conduction defect, multifocal premature ventricular contractions)

(2b) noncardiac signs or symptoms of cardiac toxicity: visual changes, anorexia, nausea, vomiting, diarrhea, abdominal pain, confusion, headache

(3) patient at high risk for toxicity - one or more of the following:

(3a) unstable or declining renal function

(3b) low serum potassium level

(3c) hypoxia

(3d) recent increase or change in diuretic dose

(3e) advanced age

(3f) hypothyroidism

(3g) magnesium depletion

(3h) hypercalcemia

(3i) acute myocardial infarction or ischemia

(4) initiation of digoxin therapy

(5) adjustment in dose

(6) inpatients: admission level if a digoxin level is not available from within the last 9 months

(7) outpatients: routine annual monitoring for patients on stable dosage schedule (inappropriate if level drawn less than 10 months from prior level)

 

Testing should not be done until the drug has fully distributed from a recent dose:

(1) IV dose: > 4 hours

(2) oral dose: > 6 hours

 

Testing after starting digoxin or making a change in dose should be done only after the drug has reached steady state levels (in > 5 half-lives, > 8 – 10 days).