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Tentative identification of a digoxin-like immunoreactive substance
P A Toseland1, P R Oldfield, G M Murphy
1Department of Clinical Chemistry, Guy's Hospital, London, U.K.
Therapeutic Drug Monitoring
|January 1, 1988
Summary
Discrepancies in digoxin immunoassay results led to the isolation of a digoxin-like immunoreactive substance (DLIS). Bile acids are hypothesized as the source of DLIS in patients with impaired renal and liver function and in neonates.
Area of Science:
- Clinical Chemistry
- Analytical Chemistry
- Biochemistry
Background:
- Digoxin immunoassays can yield variable results, particularly in patients with compromised renal and liver function.
- A digoxin-like immunoreactive substance (DLIS) has been observed in certain patient populations, including neonates.
- The source and nature of DLIS remain incompletely understood.
Purpose of the Study:
- To investigate the cause of discrepant digoxin measurements in a patient with renal and liver impairment.
- To isolate and characterize the substance responsible for the digoxin-like immunoreactivity.
- To explore potential sources of DLIS, including bile acids.
Main Methods:
- Utilized three independent immunoassays for digoxin concentration measurement.
- Employed high-pressure liquid chromatography (HPLC) to isolate the DLIS from plasma samples.
- Analyzed the isolated fraction using fast atom bombardment-mass spectrometry (FAB-MS).
Main Results:
- Significant differences in digoxin concentrations were observed across the three immunoassays.
- HPLC successfully isolated a digoxin-like immunoreactive substance (DLIS).
- FAB-MS data supported the hypothesis that excess bile acids are a potential source of DLIS.
Conclusions:
- Discrepant digoxin immunoassay results can be attributed to the presence of DLIS.
- Excess bile acids are a plausible source of DLIS in patients with hepatic and renal impairment.
- The findings may elucidate the presence of DLIS in neonates.