Age, chloride ion, high-density lipoprotein cholesterol, blood urea nitrogen, Deslanoside, and hypoglycemic drugs were identified as independent factors influencing serum digoxin concentration in a cross-sectional study of 178 patients at a tertiary hospital in China.
Key Findings
Results
More than half of patients had serum digoxin concentrations at or above the 0.9 ng/mL safety cutoff recommended by ACCF/AHA heart failure guidelines.
Among 178 patients, those with SDC < 0.9 ng/mL accounted for 43.26%, while patients with SDC ≥ 0.9 ng/mL comprised 56.74%.
The median SDC was 1.05 ng/mL (IQR: 0.54, 1.60).
The study used a cutoff value of 0.9 ng/mL corresponding to the proposed safety upper limit by international heart failure recommendations (ACCF/AHA).
Data were collected retrospectively from Jiande First People's Hospital in China.
Results
Older age was independently associated with higher serum digoxin concentrations.
Multivariate logistic regression showed age was significantly associated with SDC ≥ 0.9 ng/mL (OR = 1.10, 95% CI: 1.05–1.15, P < .001).
Each one-unit (year) increase in age was associated with a 10% increase in the odds of having SDC ≥ 0.9 ng/mL.
Age was included in the final stepwise regression model after first passing the univariate threshold of P < .1.
Results
Higher chloride ion (Cl-) levels were independently associated with lower serum digoxin concentrations.
Multivariate logistic regression showed Cl- was negatively associated with SDC ≥ 0.9 ng/mL (OR = 0.87, 95% CI: 0.81–0.94, P < .001).
Each unit increase in Cl- was associated with a 13% decrease in the odds of having SDC ≥ 0.9 ng/mL.
Cl- was retained as an independent factor in the final multivariate model.
Results
Higher high-density lipoprotein cholesterol (HDLC) levels were independently associated with lower serum digoxin concentrations.
Multivariate logistic regression showed HDLC was strongly negatively associated with SDC ≥ 0.9 ng/mL (OR = 0.08, 95% CI: 0.02–0.30, P < .001).
Higher HDLC was associated with a 92% reduction in the odds of having SDC ≥ 0.9 ng/mL.
HDLC was retained as an independent factor in the final multivariate model.
Results
Higher blood urea nitrogen (BUN) levels were independently associated with higher serum digoxin concentrations.
Multivariate logistic regression showed BUN was positively associated with SDC ≥ 0.9 ng/mL (OR = 1.15, 95% CI: 1.07–1.25, P < .001).
Each unit increase in BUN was associated with a 15% increase in the odds of having SDC ≥ 0.9 ng/mL.
BUN is a marker of renal function, suggesting that reduced renal clearance may contribute to elevated digoxin levels.
Results
Concomitant use of Deslanoside was independently associated with higher serum digoxin concentrations.
Multivariate logistic regression showed Deslanoside use was positively associated with SDC ≥ 0.9 ng/mL (OR = 5.41, 95% CI: 1.39–21.15, P = .015).
Patients receiving Deslanoside had more than five times the odds of having SDC ≥ 0.9 ng/mL compared to those not receiving it.
Deslanoside is another cardiac glycoside, suggesting additive or interactive effects when used alongside digoxin.
Results
Concomitant use of hypoglycemic drugs was independently associated with lower serum digoxin concentrations.
Multivariate logistic regression showed hypoglycemic drug use was negatively associated with SDC ≥ 0.9 ng/mL (OR = 0.30, 95% CI: 0.10–0.89, P = .030).
Patients taking hypoglycemic drugs had 70% lower odds of having SDC ≥ 0.9 ng/mL compared to those not taking them.
Hypoglycemic drugs were retained as an independent factor in the final stepwise regression model.
Methods
The study identified six independent factors influencing serum digoxin concentration through multivariate logistic regression.
Variables with P < .1 in univariate analysis were entered into a stepwise regression model, and those with P < .05 were retained in the final model.
The six independent factors were: age, chloride ion (Cl-), high-density lipoprotein cholesterol (HDLC), blood urea nitrogen (BUN), Deslanoside, and hypoglycemic drugs.
The study was cross-sectional and retrospectively analyzed data from 178 patients at Jiande First People's Hospital in China.
Patient data included SDC, demographic characteristics, biochemical parameters, comorbidities, and medication use.
What This Means
This research suggests that controlling digoxin blood levels is complex because many patient-specific factors influence how the drug accumulates in the body. In a study of 178 patients at a Chinese hospital, researchers found that more than half had digoxin levels at or above a key safety threshold (0.9 ng/mL), with a median level of 1.05 ng/mL. By analyzing patient records, the team identified six factors independently linked to whether a patient's digoxin level fell above or below this threshold: older age and higher blood urea nitrogen (a marker of kidney function) were associated with higher digoxin levels, while higher chloride ions and higher HDL cholesterol ('good' cholesterol) were associated with lower levels. Taking another cardiac glycoside called Deslanoside alongside digoxin was strongly associated with higher digoxin levels, while taking blood sugar-lowering medications was associated with lower levels.
These findings matter because digoxin has a very narrow window between a therapeutic dose and a toxic one, making it one of the more challenging drugs to manage safely. This research suggests that clinicians monitoring digoxin therapy should pay close attention to a patient's age, kidney function (as reflected by BUN), electrolyte and cholesterol levels, and any other medications they are taking — particularly other cardiac glycosides. Patients who are older or who have reduced kidney function may be at particular risk of accumulating higher digoxin levels.
Because this was a cross-sectional study at a single hospital in China, the findings reflect associations rather than proven causes, and may not apply universally to all patient populations. Nonetheless, this research provides a useful reference for clinicians seeking to individualize digoxin dosing and monitoring strategies, particularly in settings where therapeutic drug monitoring is routinely performed.
Huang W, Dong Z, Chen G. (2026). An analysis of digoxin serum concentrations and influencing factors: A cross-sectional study from a tertiary hospital in China.. Medicine. https://doi.org/10.1097/MD.0000000000049186