Asymptomatic raised alkaline phosphatase

The elevation of alkaline phosphatase levels in an asymptomatic individual should be confirmed by anlysis of a repeat blood sample.

Chronic elevation of alkaline phosphatase levels in an otherwise well individual may be:

• a variant of normal
• due to bone disease
• due to liver disease:
  • liver disease is supported by elevated gamma-GT levels

Sometimes it is useful to look at the relationship of ALP to bilirubin and lactate dehydrogenase (LD) levels (1)

Notes:

• if alkaline phosphatase is raised in an asymptomatic patient and serum bilirubin, liver transaminases, creatinine, adjusted calcium, thyroid function, and blood count are normal (2):
  • consider growth spurts in adolescents, pregnancy in women, drugs, and age related increases
  • as most likely sources are either bone or liver, differentiate by measuring GGT (raised in liver) and investigate accordingly
  • for liver cases investigate with abdominal ultrasound scan (cholestasis and hepatic space occupying lesion) and antimitochondrial antibodies (primary biliary cirrhosis)
  • for bone cases investigate vitamin D

Reference:

• NHS Exeter Clinical Laboratory - Alkaline Phosphatase (Accessed 1/9/19)
• Shipman KE et al. Interpreting an isolated raised serum alkaline phosphatase level in an asymptomatic patient.BMJ. 2013 Apr 3;346:976