Quantitative determination of serum bile acids using a 7alpha-hydroxysteroid dehydrogenase

Area of Science:

• Biochemistry
• Enzymology
• Clinical Chemistry

Background:

• Bile acids are crucial for digestion and are key indicators of liver function.
• Accurate measurement of specific bile acid profiles is essential for diagnosing hepatobiliary disorders.
• Current methods may lack specificity or require complex procedures.

Purpose of the Study:

• To develop and validate a specific enzymatic-fluorimetric method for quantifying 7alpha-hydroxy bile acids in serum.
• To establish reference ranges for these bile acids in healthy individuals.
• To assess the diagnostic utility of 7alpha-hydroxy bile acids in liver diseases.

Main Methods:

• Utilized a crude 7alpha-hydroxysteroid dehydrogenase isolate from P. testosteroni, requiring NADP.
• Developed a specific and reliable enzymatic-fluorimetric assay for serum bile acid determination.
• Validated the method using normal and jaundiced serum samples, assessing recovery rates.

Main Results:

• The method demonstrated an overall recovery of 85% in serum samples.
• Healthy subjects had a mean serum 7alpha-hydroxy bile acid concentration of 2.5 mumoles/L, comprising 73% of total bile acids.
• Patients with liver disease showed a significantly increased proportion of 7alpha-hydroxy bile acids (mean 92.5%, p < 0.001).

Conclusions:

• The enzymatic-fluorimetric method provides a simple, specific, and reliable means for measuring 7alpha-hydroxy bile acids.
• Increased serum 7alpha-hydroxy bile acids are a significant indicator of parenchymatous liver disease and cholestatic disorders.
• This assay holds potential as a valuable diagnostic tool for liver function assessment.