Digoxin

Specimen

Serum, collected at least 6 hours after the dose. Please provide details of the daily dosage, the time of the last dose and the sample time.

Units

ug/L

Reference Range

0.5 – 1.0 ug/L

Test Usage

Monitoring of the digoxin concentration is not indicated in the majority of patients on maintenance treatment, especially if a clear therapeutic response has been obtained, but it may be valuable in certain circumstances :

When there is an initial poor response to treatment

• In helping to confirm a diagnosis of digoxin toxicity
• When previous drug history is uncertain
• To decide if continued therapy is justified
• In patients with changing renal function
• In patients starting or discontinuing interacting drugs such as Verapamil or quinidine.

The laboratory also measures and reports both creatinine and potassium on each request for digoxin. Creatinine is analysed to assess renal function, and thus potential impaired elimination of the drug. Potassium is analysed because hypokalaemia is associated with an enhanced response to cardiac glycosides, so digoxin toxicity can occur even within the quoted therapeutic range if the potassium is low.

Availability

Local test

Turnaround Time: 1 day

Can be added on to an existing request up to 4 days following sample receipt