Clinical value of serum digoxin assays in outpatients: improvement by the standardization of blood sampling.
Everyday physical activity previously has been shown to affect serum digoxin concentrations. Standardized rest in the supine position increases outpatient serum digoxin levels 0% to 75%. The present study comprising 56 outpatients treated with digoxin was undertaken to elucidate the clinical importance of a standardized period of rest before collection of the blood sample. Blood samples were taken about 24 hours after the latest dose, before and after 2 hours of rest in the supine position. A careful clinical examination, including electrocardiogram (ECG) findings, systolic time intervals, and chest x-ray studies, was performed to identify adverse effects/intoxication or failure of digitalis treatment. Signs of failure of digitalis treatment occurred in 12% of the patients, with a serum digoxin concentration of 0.68 +/- 0.15 (mean +/- SD) nmol/L before rest and 0.85 +/- 0.22 nmol/L after rest. Eleven percent showed signs of adverse effects/intoxication, with serum digoxin concentrations of 1.70 +/- 0.70 nmol/L before rest and 2.08 +/- 0.80 nmol/L after rest. The serum digoxin concentrations of the adequately treated patients (77%) were 1.02 +/- 0.35 nmol/L before rest and 1.28 +/- 0.41 nmol/L after rest. The importance of standardized rest before blood sampling is illustrated by the fact that only one third of the patients without signs of adverse effects/intoxication or failure of digitalis treatment had serum digoxin concentrations within the therapeutic range most commonly used (1.2 to 2.6 nmol/L) without supine rest. If allowed to rest in the supine position before blood sampling, approximately 60% of the adequately treated patients had serum digoxin concentrations within this range.(ABSTRACT TRUNCATED AT 250 WORDS)
Jogestrand
T
T
Department of Clinical Physiology, Karolinska Hospital, Stockholm, Sweden.
Edner
M
M
Haverling
M
M
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001281:Atrial Fibrillation / Q000188:drug therapy; D001800:Blood Specimen Collection / Q000379:methods*; D004077:Digoxin / Q000009:adverse effects / Q000097:blood* / Q000627:therapeutic use; D004562:Electrocardiography; D005260:Female; D006333:Heart Failure / Q000188:drug therapy; D006801:Humans; D008297:Male; D008875:Middle Aged; D010044:Outpatient Clinics, Hospital; D011188:Potassium / Q000097:blood; D013902:Radiography, Thoracic; D012146:Rest; D013484:Supination; D013599:Systole; D013997:Time Factors
D004077:Digoxin; D011188:Potassium