Pitfalls in the application of digoxin determinations.
The radioimmunoassay of digoxin is one of the most important services of the nuclear medicine laboratory. Precision and accuracy in the performance of the test are especially critical. A number of commerical kits are available and reliable. Pitfalls to be avoided includelimited availability or delay in performance of the assay; failure to consider senitizing factors; drawing the blood sample too soon after a digoxin dose; failure to consider desensitizing factors; forgetting that renal function is a major determinant of blood and tissue digoxin levels; assuming patient compliance and uniform intestinal absorption (bioavailiability with all digoxin preparations in all patients; attempting to interpret digoxin levels without the necessary clinical information; and failure to deliver the result to the proper person. If one avoids these pitfalls, and important service will be rendered in the evaluation of the patient requiring digitalis therapy.