Digoxin
Code:15003|CPT:80162|LOINC:10535-3
| Includes | Digoxin, Serum |
|---|
Analysis details
Methodology
- Kinetic interaction of microparticles in solution (KIMS)
- Fluorescence polarization immunoassay (FPIA)
Expected Turnaround Time
1 day
Special Instructions
- Do not eat for 2–3 hours before the blood draw; water is allowed.
- Avoid smoking for at least 30 minutes before collection.
- Verify that the prescribed medication is digoxin and not digitoxin.
- Ask about high-dose biotin use; stop biotin supplements for a minimum of 72 hours prior to collection to prevent assay interference.
How to use
The Digoxin, Serum test (digoxin level; Lanoxin) is used to track therapeutic concentrations during both loading (digitalization) and maintenance therapy. It assists clinicians in individualizing dosing to achieve efficacy while minimizing the risk of underexposure or toxicity. This measurement is also applied when toxicity is suspected or when the clinical response seems subtherapeutic despite prescribed therapy. Results guide further management, including dose modification and investigation of contributing factors.
Limitations
Digoxin is a foxglove-derived cardiac glycoside that has been used in clinical practice for more than two centuries to relieve symptoms of heart failure and to control ventricular response in supraventricular tachyarrhythmias. After oral dosing, bioavailability is approximately 75%–95%, with about 20%–25% bound to plasma proteins. Metabolism is minimal, and 50%–75% of the dose is eliminated unchanged in the urine. With normal renal function, the elimination half-life is about 36–48 hours; in renal failure it prolongs to roughly 3.5–5 days. The drug accumulates in tissues, and steady state is typically achieved after 1–2 weeks of regular administration. A commonly referenced therapeutic range is 0.8–2.0 ng/mL. However, clinically important toxicity can occur at lower concentrations in the setting of hypokalemia, hypomagnesemia, hypoxia, structural heart disease, or hypercalcemia. Acute poisoning can produce life‑threatening ventricular arrhythmias, and gastrointestinal complaints are frequently among the earliest manifestations. Endogenous digoxin‑like immunoreactive substances—especially in renal failure (uremia)—may interfere with some immunoassays and render results unreliable.
| Unit | ng/mL |
|---|---|
| Reference interval | — |
| Indications | Ongoing surveillance of serum levels while a patient is receiving digoxin, Workup of suspected digoxin toxicity, including nausea, vomiting, dizziness, neuropsychiatric changes, cardiac arrhythmias, and visual disturbances such as xanthopsia, Evaluation of inadequate clinical response or concern for subtherapeutic effect |
Possible Causes of Abnormal Results
Increased levels
- amiodarone
- hepatic failure
- preagonal states
- quinidine
- renal failure
- uremia
- verapamil
Decreased levels
- aluminum-containing agents
- antacids
- bismuth-containing agents
- laxatives
- magnesium-containing agents
- rifampin
Specimen Requirements
| Specimen | Serum |
|---|---|
| Container | Gold/Tiger Top (SST, Gel Separator) |
| Volume | 1 mL (min 0.7 mL) |
| Storage Instructions | Room temperature, Refrigerated, Frozen |
References
Antman EM, Wenger TL, Butler VP Jr, et al. Treatment of 150 cases of life-threatening digitalis intoxication with digoxin-specific fab antibody fragments. Final report of a multicenter study. Circulation. 1990; 81(6):1744-52. PubMed 2188752Graves SW. Endogenous digitalis-like factors. Crit Rev Clin Lab Sci. 1986; 23(3):177-200 (review). PubMed 3015491Graves SW, Brown B, Valdes R Jr. An endogenous digoxin-like substance in patients with renal impairment. Ann Intern Med. 1983; 99(5):604-608. PubMed 6638719Haddy FJ. Endogenous digitalis-like factor or factors. N Engl J Med. 1987; 316(10):621-623. PubMed 3027560Halkin H, Kleiner A, Saginer A, et al. Value of serum digoxin concentration measurement in the control of digoxin therapy in atrial fibrillation. Isr J Med Sci. 1979; 15(6):490-493. PubMed 457382Presti S, Friedman D, Saslow J, et al. Digoxin toxicity in a premature infant: Treatment with Fab fragments of digoxin-specific antibodies. Pediatr Cardiol. 1985; 6(2):91-93. PubMed 4059073Smith TW, Butler VP Jr, Haber E, et al. Treatment of life-threatening digitalis intoxication with digoxin-specific Fab antibody fragments. N Engl J Med. 1982; 307(22):1357-1362. PubMed 6752715Springer M, Olson KR, Feaster W. Acute massive digoxin overdose: Survival without use of digitalis-specific antibodies. Am J Emerg Med. 1986; 4(4):364-368. PubMed 3718631Stone JA, Soldin SJ. An update on digoxin. Clin Chem. 1989; 35(7):1326-1331. PubMed 2667796Tsang P, Gerson B. Digoxin monitoring in the geriatric patient. Drug Monitoring and Toxicology. 1991;12.Tsang P, Gerson B. Understanding digoxin use in the elderly patient. Clin Lab Med. 1990; 10(3):479-492. PubMed 2253445Vine DL. What is the practical value of digitalis in CHF? Kans Med. 1992; 93(7):231-232. PubMed 1507738Withering W. An Account of the Foxglove, and Some of its Medical Uses: With Practical Remarks on Dropsy, and Other Diseases. Birmingham: Printed by M. Swinney. London, England: GGJ and J. Robinson, Paternoster-Row;1785.Woolf AD, Wenger T, Smith TW, et al. The use of digoxin-specific Fab fragments for severe digitalis intoxication in children. N Engl J Med. 1992; 326(26):1739-1744. PubMed 1594015Yancy CW, Jessup M, Bozkurt B, et al. 2013 ACCF/AHA Guideline for the Management of Heart Failure. J Am Coll Cardiol. 2013 Oct 15; 62(16):147-239. PubMed 23747642
Applied Therapeutic Drug Monitoring. Vol 2. Edited by TP Moyer, RL Boeckx. Washington, DC, American Association for Clinical Chemistry, 1984.
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.
Jortani SA, Voldew R Jr: Digoxin and its related endogenous factors. Crit Rev Clin Lab Sci 1997;34:225-274.