Basal serum pancreatic polypeptide is dependent on age and gender in an adult population

This study is the first epidemiologically based study of basal levels of serum pancreatic polypeptide (s-PP). The basal level of serum PP has become a field of interest mainly due to the role of PP as an endocrine tumour marker, and as a marker of pancreatic neuroendocrine function after pancreas transplantation and in the case of diabetic autonomic neuropathy. The study population consisted of primarily Caucasian adults representative of a general population living around Copenhagen. Serum pancreatic polypeptide was measured in random serum samples from fasting persons (n = 623), aged 25-64 y, using a monospecific radioimmunoassay. Fasting serum pancreatic polypeptide depended on age and gender. The results demonstrated that fasting pancreatic polypeptide levels increase exponentially with age. Fitted separately for each sex, basal serum pancreatic polypeptide was found to increase by approximately 3% per year of age. Males had higher concentrations of pancreatic polypeptide in serum compared to age-matched females. Normal range and 95% reference intervals are given. The lower limit for the reference interval of the normal range was close to detection limit. We conclude that discrepancies among earlier reports on the fasting levels of serum pancreatic polypeptide are most likely due to lack of adjustment for age and gender. Thus, variation due to age and gender should be considered in evaluating fasting levels of serum pancreatic polypeptide. Whether similar considerations are important when evaluating stimulated serum pancreatic polypeptide levels remains to be elucidated.