title: Increased parathyroid hormone-related peptide in patients with hypercalcemia associated with islet cell carcinoma.
abstract: OBJECTIVE
  To report the high prevalence of increased parathyroid hormone-related peptide (PTHrP) in patients with islet cell carcinoma and associated hypercalcemia.
  
  
  METHODS
  We conducted a retrospective study of PTHrP levels in patients with hypercalcemia and eucalcemia associated with islet cell carcinoma and compared these findings with those in healthy subjects.
  
  
  METHODS
  Using a sensitive PTHrP immunochemiluminometric assay, we measured PTHrP levels in 17 patients with islet cell carcinoma and 110 healthy subjects. The differences between PTHrP levels in patients with normal and those with high serum calcium concentrations were analyzed statistically.
  
  
  RESULTS
  PTHrP levels were significantly higher (P < 0.01) in 10 patients with hypercalcemia and islet cell carcinoma (median, 14.0 pmol/L; range, undetectable to 40.1) than in 7 patients with eucalcemia and islet cell carcinoma (median, undetectable; range, undetectable to 1.3 pmol/L) or in the 110 healthy subjects (median, undetectable; range, undetectable to 4.2 pmol/L). The range of increased PTHrP levels in hypercalcemic islet cell carcinoma was 2 to 20 times the upper normal limit (2.0 pmol/L). Decreased PTHrP and serum calcium and increased parathyroid hormone levels were demonstrated in two patients after effective therapy. For all seven eucalcemic patients with islet cell carcinoma, PTHrP levels did not differ significantly from those in healthy subjects.
  
  
  CONCLUSIONS
  PTHrP levels are increased in a substantial proportion of patients with hypercalcemia and islet cell carcinoma and seem to decrease after treatment of the underlying tumor. Measurement of PTHrP levels may be useful for confirming the diagnosis of hypercalcemia associated with malignant disease and for monitoring of therapy.
authors.affiliation: Department of Laboratory Medicine and Pathology, Mayo Clinic Rochester, MN 55905, USA.
authors.forename: T J
authors.initials: TJ
authors.lastname: Wu
authors.forename: C L
authors.initials: CL
authors.lastname: Lin
authors.forename: R L
authors.initials: RL
authors.lastname: Taylor
authors.forename: L K
authors.initials: LK
authors.lastname: Kvols
authors.forename: P C
authors.initials: PC
authors.lastname: Kao
mesh_terms: D000328:Adult; D000368:Aged; D018273:Carcinoma, Islet Cell / Q000097:blood* / Q000150:complications; D005260:Female; D006801:Humans; D006934:Hypercalcemia / Q000097:blood* / Q000209:etiology; D008297:Male; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000097:blood*; D010190:Pancreatic Neoplasms / Q000097:blood* / Q000150:complications; D010281:Parathyroid Hormone / Q000097:blood*; D044162:Parathyroid Hormone-Related Protein; D011506:Proteins / Q000378:metabolism*; D012189:Retrospective Studies
chemical_list: D009363:Neoplasm Proteins; C470121:PTHLH protein, human; D010281:Parathyroid Hormone; D044162:Parathyroid Hormone-Related Protein; D011506:Proteins