How to Convert Digoxin Units
Digoxin levels may be reported in ng/mL in conventional unit systems or nmol/L in SI unit systems. The conversion is specific to digoxin and should not be reused for other drugs.
Labcorp's SI conversion table lists digoxin (Lanoxin) with a factor of 1.28 from ng/mL to nmol/L. Siemens digoxin assay documentation also lists the same conversion formula.
Digoxin Conversion Formula
nmol/L = ng/mL x 1.28 ng/mL = nmol/L x 0.781 Example: a digoxin result of 0.8 ng/mL equals 1.024 nmol/L.
Why Digoxin Unit Conversion Matters
Digoxin is a narrow-therapeutic-index medication. Small differences in concentration can matter, especially when kidney function, age, drug interactions, potassium levels, or symptoms change.
Unit conversion helps compare lab reports from different systems, but it does not determine whether a level is safe or appropriate. The timing of the blood draw and the patient's clinical condition are essential.
Digoxin Conversion Chart
This quick table converts common digoxin values between ng/mL and nmol/L using the factor 1.28.
| ng/mL | nmol/L | Context |
|---|---|---|
| 0.4 ng/mL | 0.51 nmol/L | Low level example |
| 0.5 ng/mL | 0.64 nmol/L | Lower monitoring range often cited for heart failure |
| 0.8 ng/mL | 1.02 nmol/L | Common target area in many protocols |
| 1.0 ng/mL | 1.28 nmol/L | Mid-range example |
| 1.2 ng/mL | 1.54 nmol/L | Upper area for some monitoring ranges |
| 1.5 ng/mL | 1.92 nmol/L | Higher level; interpret carefully |
| 2.0 ng/mL | 2.56 nmol/L | Level often associated with increased toxicity concern |
Therapeutic Range Notes
Digoxin ranges vary by indication, laboratory method, and clinical protocol. Heart failure monitoring often uses a lower target range than older broad ranges. FDA labeling notes that serum concentration measurement can help clinicians assess therapy and the likelihood of intoxication, and that levels above 2 ng/mL are associated with toxicity concern.
Never adjust a digoxin dose based only on an online conversion result. Contact a healthcare professional urgently if symptoms such as severe nausea, vomiting, confusion, visual changes, fainting, or irregular heartbeat occur.
Example Calculation
Suppose a lab report shows digoxin at 1.2 ng/mL and a reference uses nmol/L:
1.2 x 1.28 = 1.536 nmol/L The converted value is 1.536 nmol/L. The number can then be compared with a reference range that uses nmol/L, as long as the same clinical context and lab method are considered.
Frequently Asked Questions
What is the digoxin ng/mL to nmol/L conversion factor?
Multiply ng/mL by 1.28 to get nmol/L. For the reverse conversion, multiply nmol/L by 0.781.
Is 1 ng/mL digoxin the same as 1 nmol/L?
No. 1 ng/mL digoxin equals 1.28 nmol/L. A value in nmol/L will look numerically higher than the same concentration in ng/mL.
Can I use this converter for digitoxin?
No. Digitoxin has a different conversion factor. This page is only for digoxin.
Can this calculator tell if a digoxin level is toxic?
No. It only converts units. Toxicity depends on symptoms, kidney function, electrolytes, dose timing, interacting drugs, and medical history.
References
Conclusion
The digoxin conversion is straightforward: multiply ng/mL by 1.28 to get nmol/L, or multiply nmol/L by 0.781 to get ng/mL. Use the calculator above for fast unit comparison, then rely on your healthcare team and lab reference range for interpretation.