For heart failure, digoxin levels are usually targeted around 0.5–0.9 ng/mL; for atrial fibrillation, current US guidance recommends below 1.2 ng/mL when levels are measured. Samples generally need at least 6–8 hours after a dose. Toxicity can occur within the laboratory interval, especially with kidney impairment, low potassium or magnesium, or interacting medicines.
- Digoxin therapeutic range depends on the indication: heart-failure guidance specifies 0.5 to less than 0.9 ng/mL, while atrial-fibrillation guidance recommends below 1.2 ng/mL when monitoring is indicated.
- Sample timing generally requires at least 6–8 hours after the last dose; a sample immediately before the next dose is often easiest to interpret.
- Steady state usually takes approximately 7–10 days with normal kidney function and can take substantially longer with kidney impairment.
- Toxicity risk increases above 2 ng/mL, but a lower result does not exclude clinically significant toxicity.
- Kidney function determines much of digoxin clearance; dehydration or acute kidney injury can make an unchanged prescription unsafe.
- Electrolytes matter independently: potassium below 3.5 mmol/L and low magnesium increase susceptibility to digoxin-related arrhythmias.
- Interactions include amiodarone, verapamil and certain antibiotics; some medicines also slow the heart without raising the measured digoxin concentration.
- Akutte symptomer include fainting, new confusion, persistent vomiting, visual changes or a slow or irregular heartbeat, particularly when several occur together.
- Enheter are interchangeable only with conversion: 1 ng/mL equals 1 µg/L and approximately 1.28 nmol/L.
What digoxin level should your clinician target?
A digoxin level has no single universally safe target. Heart failure generally calls for a lower concentration than older laboratory intervals suggest, while atrial-fibrillation treatment also depends on heart rate, symptoms and other medicines—not simply whether the result falls inside a printed range.
The 2022 AHA/ACC/HFSA heart-failure guideline lists a serum digoxin target of 0.5 to less than 0.9 ng/mL, whereas the 2023 US atrial-fibrillation guideline recommends below 1.2 ng/mL when a concentration is measured (Heidenreich et al., 2022; Joglar et al., 2024). These are treatment targets, not guarantees that every patient within them is safe.
A laboratory may still print 0.8–2.0 ng/mL, depending on its assay and reporting policy; that interval should not override an indication-specific prescription plan. Conversely, a heart-failure result of 0.6 ng/mL may be appropriate even if a laboratory flags it as low—the flag reflects the laboratory's chosen interval, not necessarily inadequate treatment.
Kantesti er en AI-blodprøveanalysator that can help organize a digoxin result alongside kidney and electrolyte measurements, but the prescriber determines the treatment target. I'm Thomas Klein, MD, Chief Medical Officer; my first question about a result such as 1.1 ng/mL is why digoxin was prescribed, and our organisasjon og kliniske oppdrag explain that distinction between interpretation support and prescribing.
Why heart failure usually needs a lower digoxin level
Lower digoxin concentrations are preferred in heart failure because additional exposure can add risk without a proven survival benefit. Digoxin may reduce heart-failure hospitalizations in selected patients with persistent symptoms despite appropriate treatment, but it is not a substitute for the medicines that improve survival.
Det 2022 heart-failure guideline gives digoxin a selective role in symptomatic heart failure with reduced ejection fraction despite guideline-directed treatment, or when that treatment cannot be tolerated (Heidenreich et al., 2022). Its discussion reflects evidence that hospitalization benefit and concentration-related risk must be balanced; raising a result from 0.7 to 1.4 ng/mL is not an automatic improvement.
A concentration of 0,5 ng/mL does not tell you whether congestion is controlled, blood pressure is adequate or the underlying treatment plan is complete. Symptoms, weight trends, examination findings and other cardiac measurements answer different questions; our guide to NT-proBNP and heart-failure symptoms explains why a heart-failure marker is not interchangeable with a medication concentration.
Consider a hypothetical 78-year-old whose breathlessness worsens while the digoxin level remains 0.7 ng/mL: the useful next step is assessing fluid status, kidney function, adherence and the rest of the regimen, not simply increasing digoxin. If that same person develops nausea and bradycardia, the apparently reassuring concentration should not prevent an assessment for toxicity.
How atrial fibrillation changes the digoxin therapeutic range
For atrial fibrillation, digoxin monitoring supports a rate-control plan rather than defining one. The 2023 ACC/AHA/ACCP/HRS guideline recommends targeting a concentration below 1,2 ng/mL when levels are measured, with lower exposure often appropriate in patients who also have heart failure or increased toxicity risk.
Det below-1.2 ng/mL recommendation is an upper target, not a requirement to reach 1.1 ng/mL or a reason to reject a lower concentration that achieves the clinical goal (Joglar et al., 2024). Digoxin primarily slows conduction through the atrioventricular node; it does not reliably restore sinus rhythm, and it does not replace a separate assessment of stroke-prevention treatment.
Resting heart rate and exertional heart rate can tell different stories because digoxin's rate-control effect is less reliable during increased sympathetic activity. A patient with a resting pulse of 76 beats/minute may still have troublesome exertional tachycardia, so the clinician may assess activity-related symptoms or ambulatory recordings; our palpitations assessment guide describes the complementary role of laboratory tests.
There is no sensible universal dose escalation for an atrial-fibrillation level of 0.4 ng/mL without knowing the clinical response. If the patient also takes a beta-blocker and has dizziness with a pulse of 48 beats/minute, increasing digoxin could make matters worse even though the concentration looks low; combined effects on conduction matter more than the isolated number.
Why samples wait at least 6–8 hours after a dose
Digoxin samples are generally collected at least 6–8 hours after a dose because the medicine first distributes from the circulation into tissues. A sample obtained during that distribution phase can overstate the concentration used to assess maintenance treatment and may prompt an unnecessary dose change.
Det 6–8-hour interval addresses distribution, not whether breakfast was eaten or whether the laboratory is busy. A digoxin result collected 2 timer after an oral dose cannot usually be compared directly with a stable, pre-dose result; the consensus review by Andrews and colleagues emphasizes waiting at least 6 timer, ideally longer, for concentration interpretation after ingestion (Andrews et al., 2023).
An early high result is not automatically proof of toxicity, but it is not automatically harmless either. If a patient feels well and the dose history is reliable, the clinician may request a correctly timed repeat; if there is fainting, significant bradycardia or suspected overdose, assessment proceeds immediately rather than waiting 8 timer to make the result easier to interpret.
Distribution timing is distinct from a strict trough requirement, which is why medication-specific instructions matter. Our explanation of carbamazepine trough timing offers a useful comparison, but do not transfer another drug's sampling schedule to digoxin; record the actual dose time and collection time, ideally to the nearest hour.
How to schedule a useful digoxin blood test
A pre-dose sample is often the simplest way to obtain an interpretable digoxin level. The essential details are the time of the last dose, the time of collection and the prescribed schedule; follow the laboratory or prescriber's instructions rather than independently skipping treatment.
For a person taking digoxin every morning at 08.00., collection just before the next morning's dose is approximately 24 hours after the previous dose. A draw at kl. 10.00. after taking the usual morning tablet is only 2 timer later and usually unsuitable for routine maintenance interpretation; confirm in advance whether the morning dose should be taken after collection.
Evening dosing creates a different practical option: a dose at 8 p.m. followed by a sample at 08.00. gir en 12-hour interval and is generally beyond the distribution phase. However, results from 12-hour og 24-hour samples are not perfectly interchangeable, so use a consistent interval for trends whenever possible rather than treating every small difference as a physiological change.
Fasting is not ordinarily required for digoxin alone, although another ordered test may require it. Bring a record of any missed, delayed or extra doses over the preceding week; unlike the more specific conventions discussed in tacrolimus trough monitoring, the request for a digoxin level should explicitly state the intended sampling interval.
When to check digoxin levels—and when not to
Check digoxin levels when toxicity is suspected, kidney function changes, interacting medicines change, adherence is uncertain or a dose adjustment needs assessment. Stable patients do not necessarily need frequent routine concentrations; after a maintenance-dose change, an elective check usually waits until the new concentration approaches steady state.
Digoxin's elimination half-life is approximately 36–48 hours in people with normal kidney function, so a maintenance concentration commonly approaches steady state after about 7–10 days. Kidney impairment can extend that interval substantially; a level taken 2. dag after a dose reduction may still largely reflect the old regimen, although it can still contribute to an urgent safety assessment.
Routine monitoring should also include kidney function, potassium and magnesium, often at least årlig in otherwise stable patients and more frequently when age, illness or other treatment increases risk. A new diuretic, vomiting illness or change in renal function can justify earlier testing; our veileder for medikamentsikkerhetstrender explains why the event triggering a test matters as much as the calendar.
Kantesti er en AI-blodprøvetolkningsplattform that can help compare a current digoxin result with related laboratory trends when those results and the dosing history are supplied. A change from 0.6 to 1.0 ng/mL deserves a check of sample timing and kidney function before it is described as accumulation; symptoms, however, can make that review urgent rather than elective.
How kidney function can turn a stable dose unsafe
Reduced kidney clearance can raise digoxin exposure without any change in the prescribed dose. Acute kidney injury, dehydration and chronic kidney disease therefore change the meaning of a previously acceptable level; older adults with low muscle mass may have more renal impairment than their creatinine concentration suggests.
A creatinine increase from 0,9 til 1,3 mg/dL—approximately 80 to 115 µmol/L—may be clinically meaningful, especially when it occurs quickly in a small older adult. The immediate issue is the change in clearance, not whether the latest creatinine barely crosses the laboratory boundary; our low-eGFR warning signs help distinguish a laboratory trend from an illness needing prompt assessment.
Estimated GFR is less reliable during rapidly changing kidney function because creatinine has not reached equilibrium, so yesterday's calculated value may lag behind today's illness. A 3-day episode of vomiting can reduce kidney clearance and disturb electrolytes at the same time; our dehydration and GFR guide explains why a temporary trigger can still create a serious medication-safety problem.
Digoxin dosing may require a drug-dosing estimate such as creatinine clearance rather than simply copying the laboratory's body-surface-area-indexed eGFR, particularly at body-size extremes. A BUN/creatinine ratio above 20:1, when both are expressed in mg/dL, can support certain clinical hypotheses but cannot set a digoxin dose; our BUN/creatinine interpretation guide explains its limitations.
Why potassium, magnesium and calcium change toxicity risk
Low potassium and low magnesium increase susceptibility to digoxin-related arrhythmias, even when the measured digoxin level is within the laboratory interval. High calcium can also increase risk; in a substantial acute overdose, high potassium may instead reflect severe sodium–potassium pump inhibition.
Kalium under 3,5 mmol/L is generally considered low, and low extracellular potassium increases digoxin's effect at the sodium–potassium ATPase pump. A patient taking a loop diuretic may therefore develop rhythm problems at 0,8 ng/mL if potassium has fallen to 2,9 mmol/L; vår electrolyte-panel assessment guide explains why these results should be interpreted together.
Magnesium below approximately 0.7 mmol/L, depending on the laboratory, can promote arrhythmias and make potassium correction more difficult. Diuretics, gastrointestinal losses and long-term proton-pump inhibitor use can contribute; our low-magnesium causes guide explains why a normal potassium result does not make magnesium irrelevant, and why replacing either electrolyte should follow a clinician's plan.
High potassium in suspected acute digoxin poisoning is a different warning from low potassium during chronic treatment; 6.5 mmol/L or more is a severe abnormality, but lower values can still require urgent action in context. A hemolyzed sample can falsely elevate potassium, as discussed in kalium innsamlingsfeil, yet suspected poisoning must not be dismissed while arranging confirmation.
Which medicines can raise digoxin levels or cardiac risk?
Amiodarone, verapamil, quinidine and certain antibiotics can increase digoxin exposure, while other medicines add cardiac effects without necessarily raising the level. The interaction review should include prescriptions, over-the-counter products and supplements, with particular attention to new drugs started during an acute illness.
Amiodarone inhibits pathways involved in digoxin transport and clearance; a prescriber commonly reduces an existing digoxin dose by around 50% when amiodarone is started, with individualized monitoring. That is a clinical prescribing consideration, not a home-adjustment instruction; the interaction can evolve over time, and a single reassuring concentration shortly after the change does not establish long-term safety.
Clarithromycin and erythromycin can increase digoxin exposure through transport effects and, in some patients, changes in intestinal handling of the drug. A hypothetical 75-year-old who develops nausea several days after starting an antibiotic needs the interaction and kidney function reviewed, not just treatment for indigestion; our older-adult medication-effects guide shows why new symptoms deserve a complete medication reconciliation.
Beta-blockers, diltiazem and verapamil may add to atrioventricular conduction slowing, so a pulse of 45 beats/minute can be concerning despite an unremarkable digoxin result. Loop or thiazide diuretics create a different route to risk by lowering potassium or magnesium; spironolactone and its metabolites can also affect some digoxin assays, making the laboratory method relevant when a result seems inconsistent.
Which digoxin toxicity symptoms need urgent assessment?
Possible digoxin toxicity symptoms include nausea, vomiting, loss of appetite, unusual weakness, confusion, visual changes and a slow or irregular heartbeat. Fainting, chest pain, severe breathlessness, marked confusion or palpitations with dizziness require emergency assessment; do not wait for a repeat digoxin level.
New persistent vomiting, reduced appetite or unexplained confusion during digoxin treatment warrants prompt, often same-day, clinical advice—especially with recent dehydration or medication changes. A level of 0.9 ng/mL cannot rule out toxicity in that setting, and yellow-green vision or halos are possible but not required; many patients present without the visual symptoms commonly associated with the drug.
A very slow pulse, for example below 50 beats/minute, becomes particularly concerning when accompanied by dizziness, weakness or fainting; the patient's baseline and other medicines still matter. Chest pain or severe breathlessness should trigger emergency evaluation regardless of the last digoxin result, and our urgent chest-pain assessment guide explains why laboratory interpretation cannot replace immediate cardiac assessment.
If overdose is possible, contact emergency services or a poison-information service immediately, even if symptoms have not started within the first hour. When toxicity is suspected, seek advice urgently before the next dose; the assessing team will usually withhold digoxin while evaluating the situation, but patients should not make a permanent treatment change or take an extra dose to compensate.
What can make a digoxin result misleading?
An unexpected digoxin level can reflect early sampling, a reporting error, assay interference or a genuinely unsafe concentration. After digoxin-specific antibody treatment, routine total-digoxin measurements may become especially misleading because many assays detect antibody-bound drug as well as unbound drug.
First verify the units: 1 ng/mL tilsvarer 1 µg/L, mens 1 ng/mL is approximately 1.28 nmol/L. Et resultat på 1.3 nmol/L is therefore about 1.0 ng/mL, not 1.3 ng/mL; transcription mistakes and missing collection times are avoidable sources of confusion, and our sjekkliste for feil i PDF-ekstraksjon helps readers check imported laboratory data.
Digoxin-like immunoreactive substances can interfere with some assays, including in certain patients with kidney or liver dysfunction, and interference is method-dependent rather than universal. If a result rises from 0.7 to 1.6 ng/mL without a plausible dosing, timing or clinical explanation, the clinician can ask the laboratory about its method and potential cross-reactivity instead of assuming the patient took extra tablets.
Digoxin immune Fab is used for potentially life-threatening toxicity, including serious arrhythmias, severe conduction disturbance or significant hyperkalemia in the appropriate setting (Andrews et al., 2023). After treatment, total concentrations may appear high for days or longer and should not guide routine redosing; clinical status, ECG and electrolytes take priority, while dialysis generally removes digoxin poorly because much of the drug is distributed in tissues.
Does a low or high result mean your dose must change?
A digoxin dose should not be changed solely because a laboratory marks the level low or high. The prescriber needs the indication, symptoms, sample timing, recent dose history, kidney function and electrolytes; an elevated correctly timed result without symptoms still deserves prompt clinical review.
Common maintenance prescriptions use small doses such as 62.5, 125 or 250 micrograms, but the appropriate regimen depends on renal function, lean body size and clinical need. The unit conversion matters: 125 micrograms equals 0.125 mg, not 1.25 mg; confirm tablet strength and dispensing instructions whenever the packaging changes, and never estimate a replacement dose from the concentration alone.
A low result can reflect missed doses, a lower prescribed target, a long interval since the last dose or reduced absorption, so 0.4 ng/mL is not a diagnosis of treatment failure. The same general need for drug-specific interpretation appears in lithium kidney monitoring, but lithium's targets and dose-adjustment rules must never be applied to digoxin.
For an asymptomatic, correctly timed result of 2.3 ng/mL, contact the prescribing team promptly, preferably the same day, rather than waiting for a routine visit; any concerning symptoms move the situation into urgent assessment. A missed dose should be handled according to the prescription leaflet or pharmacist's advice, and 2 doses should not be taken together simply to catch up.
How to prepare a safe digoxin follow-up review
A useful follow-up review combines the digoxin concentration with symptoms, dose timing, kidney results, electrolytes and a complete medication list. Kantesti er en Analyseverktøy for blodprøver drevet av KI that can help organize supplied laboratory information, but it cannot examine you, obtain an ECG or authorize a prescription change.
Prepare 6 pieces of information: the dose and tablet strength, treatment indication, last-dose time, collection time, current symptoms and recent medication changes. Include creatinine or eGFR, potassium and magnesium from the relevant date rather than an unrelated older panel; our forklaring av AI-teknologi describes why supplied context and source quality shape the usefulness of an interpretation.
Kantesti's interpretation support should never turn a concentration such as 0,8 ng/mL into an unconditional reassurance when the patient is fainting or vomiting. As Thomas Klein, MD, I would rather see an incomplete report accompanied by an accurate symptom history than a polished report missing the dose time; our klinisk valideringsrammeverk should be read as methodology information, not proof that software can exclude an acute arrhythmia.
Privacy also belongs in the follow-up workflow: share only the records needed for the clinical question and obtain permission before uploading another person's results. Kantesti supports laboratory trend review, but an AI response in approximately 60 seconds is not emergency triage; our personvern sjekkliste for opplasting av resultater explains practical checks before sharing a PDF or photograph.
Research publications and the evidence behind this advice
The digoxin targets in this article come from cardiac guidelines, while sampling and toxicity advice also draw on a clinical consensus review. As of 8. oktober 2026, the sources cited here are the 2022 heart-failure guideline, the 2023 atrial-fibrillation guideline published in 2024, and the 2023 digoxin-toxicity consensus—not an invented 2026 recommendation.
Det 2 Zenodo publications listed below provide background on laboratory interpretation, not primary evidence for digoxin targets or antidote decisions. Their formal citations use the supplied publication titles with the organization as corporate author and no assumed publication date; ResearchGate and Academia.edu links are clearly identified as title searches, because a specific hosted copy has not been established.
Kantesti LTD. (n.d.). RDW blood test: Complete guide to RDW-CV, MCV & MCHC. Zenodo. This publication addresses red-cell indices rather than therapeutic drug monitoring; a reader comparing RDW-CV percentages with a digoxin value in ng/mL can use the RDW background publication to understand why unrelated markers cannot establish medication safety.
Kantesti LTD. (n.d.). BUN/creatinine ratio explained: Kidney function test guide. Zenodo. This background resource supports renal-context discussion but cannot translate a ratio above 20:1 into a digoxin prescription; Kantesti's medisinsk rådgivningsinformasjon describes the clinical expertise behind our educational approach, while urgent symptoms still require direct medical assessment.
Ofte stilte spørsmål
Hva er det terapeutiske området for et digoksin-nivå?
Digoksinens terapeutiske område avhenger av behandlingsindikasjonen heller enn et enkelt universelt laboratorieintervall. USAs retningslinje for hjertesvikt fra 2022 spesifiserer 0,5 til mindre enn 0,9 ng/ml, mens USAs retningslinje for atrieflimmer fra 2023 anbefaler under 1,2 ng/ml når konsentrasjoner måles. Noen laboratorier rapporterer fortsatt intervaller som 0,8–2,0 ng/ml, men disse bør ikke overstyre forskriverens indikasjonsspesifikke mål. Symptomer, nyrefunksjon, elektrolytter og tidspunkt for prøvetaking forblir nødvendig for tolkning.
Når bør et digoksin-nivå tas etter en dose?
En digoksinverdi samles vanligvis inn minst 6–8 timer etter siste dose, slik at tidlig distribusjon til vev ikke gjør resultatet misvisende. En prøve umiddelbart før neste planlagte dose er ofte praktisk og lettere å sammenligne over tid. Ved behandling én gang daglig er den prøven før dose vanligvis omtrent 24 timer etter forrige dose. Mistanke om toksisitet krever umiddelbar vurdering i stedet for å utsette omsorgen for å få en ideelt timet prøve.
Kan digitalistoksisitet forekomme med et normalt digitalisnviå?
Digoksinforgiftning kan oppstå innenfor laboratorier referanseintervall, inkludert ved konsentrasjoner under 2 ng/mL. Lavt kalium, lavt magnesium, nyresvikt og interagerende medisiner kan øke mottakeligheten eller legge til kardiologiske effekter. Et resultat på 0,8 ng/mL utelukker ikke forgiftning hos noen med oppkast, forvirring, besvimelse eller en langsom eller ujevn hjerterytme. Klinisk vurdering, et EKG og relaterte laboratorietester er nødvendig når forgiftning mistenkes.
Hvor lenge etter en doseendring bør digoksin-nivåene kontrolleres?
Etter en endring i vedlikeholdsdosen, venter en elektiv digoksinverdi vanligvis omtrent 7–10 dager hos en person med normal nyrefunksjon. Digoksins vanlige eliminasjons halveringstid er omtrent 36–48 timer, og flere halveringstider trengs for å nærme seg den nye jevne konsentrasjonen. Nyresvikt kan forlenge denne ventetiden betydelig. Nye symptomer eller mistenkt toksisitet rettferdiggjør tidligere vurdering og testing i stedet for å vente på jevn tilstand.
What digoxin toxicity symptoms need emergency help?
Fainting, chest pain, severe breathlessness, marked confusion or palpitations with dizziness during digoxin treatment require emergency assessment. A pulse below 50 beats/minute is particularly concerning when accompanied by weakness, dizziness or fainting, although the patient's baseline matters. Persistent vomiting, new visual changes or reduced appetite warrant prompt clinical advice, especially after dehydration or a medication change. Do not wait for a repeat digoxin level if serious symptoms or possible overdose are present.
Does a high digoxin level mean I should stop taking it?
A high digoxin level requires prompt advice from the prescribing team, but the result alone should not lead to an unsupervised permanent treatment change. An asymptomatic, correctly timed concentration above 2 ng/mL deserves prompt review of the dose, kidney function, electrolytes and interactions. If toxicity symptoms are present, seek urgent assessment before the next dose; the clinical team will usually withhold digoxin while evaluating the situation. An early sample taken only 2 hours after a dose may need a correctly timed repeat, but serious symptoms must not be dismissed as a timing issue.
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📚 Refererte forskningspublikasjoner
Klein, T., Mitchell, S., & Weber, H. (2026). RDW-blodprøve: komplett veiledning til RDW-CV, MCV og MCHC. Kantesti KI medisinsk forskning.
Klein, T., Mitchell, S., & Weber, H. (2026). Forklaring av BUN/kreatinin-forhold: Veiledning for nyrefunksjonstester. Kantesti KI medisinsk forskning.
📖 Eksterne medisinske referanser
Heidenreich PA et al. (2022). 2022 AHA/ACC/HFSA Guideline for the Management of Heart Failure. Circulation.
Joglar JA et al. (2024). 2023 ACC/AHA/ACCP/HRS Retningslinje for diagnostisering og behandling av atrieflimmer. Circulation.
Andrews P et al. (2023). Diagnosis and practical management of digoxin toxicity: a narrative review and consensus. European Journal of Emergency Medicine.
⚕️ Medisinsk ansvarsfraskrivelse
Denne artikkelen er kun for informasjonsformål og utgjør ikke medisinsk rådgivning. Rådfør deg alltid med en kvalifisert helsepersonell for beslutninger om diagnose og behandling.
E-E-A-T tillitssignaler
Experience
Klinisk gjennomgang ledet av lege av arbeidsflyter for laboratorietolkning.
Expertise
Fagområde laboratoriemedisin med fokus på hvordan biomarkører oppfører seg i klinisk kontekst.
Authoritativeness
Skrevet av Dr. Thomas Klein med gjennomgang av Dr. Sarah Mitchell og Prof. Dr. Hans Weber.
Trustworthiness
Evidensbasert tolkning med tydelige oppfølgingsveier for å redusere uro.