Concentrations of serotonin in plasma--a test for appendicitis?

We assessed the value of measuring serotonin (5-hydroxytryptamine) in plasma (by HPLC) in the diagnosis of acute appendicitis. Values for patients with subsequently confirmed appendicitis (11-145 nmol/L, median 70 nmol/L) significantly (P congruent to 0.005) exceeded those for patients with abdominal pain in whom appendicitis was only a possible diagnosis (2-45 nmol/L, median 20 nmol/L). The results for appendicitis patients were bimodally distributed, with low results found in patients where surgery revealed gangrenous appendicitis with little viable appendicular tissue. We conclude that measuring serotonin may be of value in confirming or excluding the diagnosis of early acute appendicitis where the physical signs are equivocal, and thus helps reduce unnecessary appendectomies. However, serotonin is of little help in diagnosing gangrenous appendicitis, where physical signs are more likely to be clearcut.