Persistently elevated alkaline phosphatase

Area of Science:

• Biochemistry
• Hepatology
• Clinical Medicine

Background:

• Persistent elevation of serum alkaline phosphatase (ALP) necessitates investigation to rule out underlying pathology.
• Common causes include hepatobiliary and bony diseases, which were excluded in this case.

Observation:

• A 32-year-old overweight male presented with asymptomatic, persistently elevated serum ALP (250-300 U/L).
• Initial alanine transaminase was marginally elevated but normalized with weight loss; abdominal imaging showed fatty liver.
• Extensive serological tests for hepatobiliary disease were negative.

Findings:

• Isoenzyme electrophoresis revealed normal liver and bone ALP fractions.
• A grossly elevated intestinal fraction of alkaline phosphatase was identified as the sole cause of the elevated ALP.
• This suggests a benign biochemical finding rather than significant gastrointestinal pathology.

Implications:

• Elevated intestinal alkaline phosphatase should be considered in unexplained hyperphosphatasaemia, especially when typical pathologies are absent.
• This finding underscores the importance of ALP isoenzyme analysis for accurate diagnosis.
• An elevated intestinal ALP fraction can represent a benign condition, avoiding unnecessary investigations for gastrointestinal pathology.