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HelpTest Code FRDIG Digoxin, Free, Serum
Reporting Name
Digoxin, Free, SUseful For
Evaluating recrudescent (breakthrough) digoxin toxicity in renal-failure patients
Assessing the need for more antidigoxin Fab to be administered
Deciding when to reintroduce digoxin therapy
Monitoring patients with possible digoxin-like immunoreactive factors (DLIFs)
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
SerumSpecimen Required
Patient Preparation: For 12 hours before specimen collection do not take multivitamins or dietary supplements containing biotin (vitamin B7), which is commonly found in hair, skin, and nail supplements and multivitamins.
Collection Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions:
1. Draw blood 6 to 8 hours after last dose of digoxin.
2. Serum gel tubes should be centrifuged within 2 hours of collection.
3. Red-top tubes should be centrifuged, and the serum aliquoted into a plastic vial within 2 hours of collection.
Specimen Minimum Volume
0.6 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Refrigerated (preferred) | 7 days | |
| Frozen | 180 days |
Reference Values
<16 years:
Therapeutic ranges have not been established for patients who are under 16 years of age. In adults, the suggested serum free digoxin therapeutic range is 0.4-0.9 ng/mL.
Toxic concentration: ≥3.0
≥16 years:
0.4-0.9 ng/mL
Toxic concentration: ≥3.0 ng/ mL
Day(s) Performed
Monday through Sunday
Test Classification
This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
80163
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| FRDIG | Digoxin, Free, S | 3562-6 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| FRDIG | Digoxin, Free, S | 3562-6 |
Interpretation
The target therapeutic level is 0.4 to 0.9 ng/mL. Toxicity may be seen when free digoxin concentrations are 3.0 ng/mL or higher. Pediatric patients may tolerate higher concentrations.
Therapeutic concentrations for free digoxin are 25% lower than therapeutic values for total digoxin due to the separation of protein-bound digoxin in the assay.
Clinical Reference
1. Jortani SA, Pinar A, Johnson NA, Valdes R Jr: Validity of unbound digoxin measurements by immunoassays in presence of antidote (Digibind). Clin Chim Acta. 1999;283:159-169
2. DIGIBIND Digoxin Immune FAB (Ovine). Package insert. GlaxoSmithKline; 2003
3. Moyer TP, Boeckx RL, eds: Applied Therapeutic Drug Monitoring. Vol 2. American Association for Clinical Chemistry Press; 1984
4. Jortani SA, Voldes R Jr: Digoxin and its related endogenous factors. Crit Rev Clin Lab Sci. 1997;34:225-274
5. Datta P, Hinz V, Klee G: Comparison four digoxin immunoassays with respect to interference from digoxin-like immunoreactive factors. Clin Biochem. 1996;29(6):541-547
6. Soldin SJ: Free drug measurements. When and why? An overview. Arch Pathol Lab Med. 1999;123:822-823
7. Dickstein K, Cohen-Solal A, Filippatos G, et al: ESC guidelines for the diagnosis and treatment of acute and chronic heart failure 2008: the Task Force for the diagnosis and treatment of acute and chronic heart failure 2008 of the European Society of Cardiology. Eur Heart J. 2008;29:2388-2442
8. Milone MC, Shaw LM: Therapeutic drugs and their management. In: Rifai N, Horvath AR, Wittwer CT, eds. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics 6th ed. Elsevier; 2018800-831
Report Available
Same day/1 dayMethod Name
Ultrafiltration followed by Electrochemiluminescent Immunoassay
Forms
If not ordering electronically, complete, print, and send 1 of the following forms with the specimen:
-Cardiovascular Test Request Form (T724)
-Therapeutics Test Request (T831)