Hemoglobin interference with Du Pont Automatic Clinical Analyzer procedure for calcium

Area of Science:

• Clinical Chemistry
• Biochemistry
• Analytical Chemistry

Background:

• Accurate serum calcium measurement is vital for diagnosing various medical conditions.
• Hemoglobin is a common component in blood samples, and its properties can potentially interfere with analytical assays.

Purpose of the Study:

• To investigate the interference of hemoglobin on serum calcium determination using the Du Pont aca analyzer.
• To identify the specific mechanism behind this observed interference.

Main Methods:

• Serum samples with varying hemoglobin concentrations were analyzed for calcium using the Du Pont aca.
• Spectrophotometric analysis was employed to examine the absorption characteristics of oxyhemoglobin.

Main Results:

• Hemoglobin concentrations of approximately 2.5 g/liter or greater significantly increased apparent serum calcium values.
• The interference was attributed to the 575-nm absorption band of oxyhemoglobin.
• The analyzer's differential absorption reading at 577-600 nm did not compensate for this oxyhemoglobin interference.

Conclusions:

• Hemoglobin is a significant source of interference in serum calcium assays performed on the Du Pont aca.
• Clinical laboratories should be aware of this interference when interpreting calcium results from samples with elevated hemoglobin levels.