Ethnic 'hyperamylasaemia': clarification by isoamylase analysis

Area of Science:

• Biochemistry
• Human Genetics
• Clinical Chemistry

Background:

• Serum amylase levels are commonly used as a diagnostic marker.
• Existing reference ranges may not be universally applicable across diverse populations.
• Ethnic variations in serum enzyme levels can impact diagnostic accuracy.

Purpose of the Study:

• To investigate ethnic differences in total serum amylase and its isoenzymes (P-type and S-type) in individuals without pancreatic or salivary disease.
• To determine if current reference ranges are appropriate for diverse ethnic groups residing in the UK.
• To explore the potential genetic basis for observed variations in serum amylase activity.

Main Methods:

• Measurement of total serum amylase activity in 92 individuals from three ethnic groups (Britons, Asians, West Indians).
• Isoenzyme analysis using inhibitor and electrophoretic techniques to differentiate between pancreatic (P-type) and salivary (S-type) amylase.
• Comparison of enzyme activities against established reference ranges.

Main Results:

• Mean total amylase activity was significantly higher in West Indians (383 U/l) and Asians (317 U/l) compared to Britons (179 U/l).
• A notable proportion of Asians and West Indians had amylase levels exceeding the upper limit of the reference range for Britons.
• Increased total amylase was attributed to elevated S-type isoamylase, P-type isoamylase, or both, with good correlation between analytical methods.

Conclusions:

• Significant ethnic variations exist in serum amylase levels, particularly in S-type isoamylase, suggesting a genetic influence.
• Current reference ranges for serum amylase may lead to misdiagnosis in certain ethnic groups.
• Implementation of ethnic-specific reference ranges is crucial for accurate clinical interpretation of serum amylase levels.