Indican interference with six commercial procedures for measuring total bilirubin

Area of Science:

• Clinical Chemistry
• Analytical Biochemistry
• Medical Diagnostics

Background:

• Accurate measurement of total bilirubin is crucial for diagnosing and monitoring various medical conditions.
• Indican, a potential biomarker, can be present in patient serum, particularly in cases of renal failure.
• The impact of indican on common bilirubin assays requires thorough investigation.

Purpose of the Study:

• To evaluate the interference of indican on six commercial total bilirubin measurement procedures.
• To quantify the extent of interference caused by indican in different assay methodologies.
• To provide guidance for clinicians regarding potential inaccuracies in bilirubin measurements.

Main Methods:

• Six distinct commercial methods for total bilirubin measurement were tested.
• Known concentrations of indican were added to serum samples to simulate clinical conditions.
• Interference was quantified by measuring the change in total bilirubin levels.
• The effect of color development time on interference was assessed for specific methods.

Main Results:

• The 2,4-dichlorophenyl diazonium (Abbott) and 2,5-dichlorophenyl diazonium (Boehringer Mannheim) procedures showed significant positive interference from indican.
• The Malloy-Evelyn procedure (Harleco) exhibited minor interference.
• The Jendrassik Bilirubin Reagent System (American Monitor) and a modified Jendrassik-Grof procedure (Hoffmann-LaRoche) were unaffected by indican.
• Interference in the 2,5-dichlorophenyl diazonium procedure increased with color development time.

Conclusions:

• Certain commercial total bilirubin assays are susceptible to interference from indican.
• Falsely elevated bilirubin levels can occur in patients with renal failure due to indican.
• Clinicians should exercise caution when interpreting high total bilirubin results in patients with chronic renal disease, especially when using affected assays.