Laboratory Medicine
Test Directory / Digoxin
Digoxin
Blown clotted serum, gel barrier
| Test | Digoxin |
|---|---|
| Common Abbreviations | DIG |
| Profile | NA |
| Tube type | Blown clotted serum, gel barrier |
| Clinical Indication | Digoxin is a potent cardiac glycoside widely prescribed for the treatment of patients suffering from congestive heart failure, as well as some types of cardiac arrhythmias. Digoxin intoxication is a common and serious problem in the clinical setting. Cardiac glycosides have a low therapeutic ratio a very small difference between therapeutic & tissue toxic levels. Monitoring serum digoxin levels combined with other clinical data can provide useful information to aid in adjusting patient dosage to achieve optimal therapeutic effect while avoiding harmful toxic dosage levels. |
| Specimen Type | Blood |
| Sample type | Serum |
| Minimum Volume | 0.5mL If requesting more than 10 tests please send an additional brown clotted serum sample. |
| Special Precautions | Sample should be taken at least 6 hours after the last dose |
| Stability | 7 days at 20 - 25°C, 14 days at 2 - 8°C and 6 months at -20°C |
| Turnaround Time | Urgent: 2 hours Inpatient: 4 hours Outpatient/ GP: 24 hours |
| Laboratory | York and Scarborough |
| Reference Interval | Therapeutic Range: 0.5 - 1.0 µg/L (Recommended by the Pathology Harmonisation Reference Group) |
| Limitations | Analysis should not be performed on grossly haemolysed, icteric or lipaemic samples. The assay is unaffected by biotin < 409 nmol/L or < 100 ng/mL. No interference was observed from rheumatoid factors up to a concentration of 1630 IU/mL. No interference was observed from IgG up to a concentration of 7.0 g/dL. No interference was observed from Albumin up to a concentration of 7.0 g/dL. Samples should not be taken from patients receiving therapy with high biotin doses (i.e. > 5 mg/day) until at least 8 hours following the last biotin administration. In vitro tests were performed on 16 commonly used pharmaceuticals. No interference with the assay was found. In addition, a number of special cardiac drugs were tested. No interference with the assay was found. Uzara, nabumetone, hydrocortisone, pentoxifylline and canrenone were identified to cause falsely elevated digoxin values at concentrations of the recommended daily dose. Digoxin like immunoreactiv substances (DLIS) have been identified in blood from patients with renal failure, liver failure, and pregnant women in their third trimester. Studies have shown that the presence of DLIS in a sample can result in a false elevation of digoxin when assayed by commercially available immunoassays. The therapeutic antibody fragments against digitalis (e.g. DigiFab, DigiBind) will interfere with immunoassay measurements. Therefore, the manufacturer of DigiFab recommends obtaining samples for determination of digoxin concentration prior to antidote administration. As a consequence Digoxin concentrations may be falsely elevated if measured in the presence of the antidote until the Fab fragments are eliminated from the body. In rare cases, interference due to extremely high titers of antibodies to analyte-specific antibodies, streptavidin or ruthenium can occur. These effects are minimized by suitable test design. |
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