Endocrine Abstracts

The use of 24 h urinary 5-hydroxyindolacetic acid (5-HIAA) concentrations to detect carcinoid patients is a well established procedure while random urinary 5-hydroxyindolacetic acid/creatinine ratio (5-HIAA/cr) may also offer a simpler approach in the diagnosis of carcinoid tumours. However, there is uncertainty regarding the ability of these tests to offer a prognostic indicator for patients.

We retrospectively reviewed the initial paired urinary 5-HIAA/cr and 24 h urinary 5-HIAA results for 176 carcinoid patients diagnosed between 2005 and 2008. The mortality and dates of death for this population were investigated and Kaplan–Meier survival plots (0, 180, 360, 540 and 720 days) created for different values of the two tests. During this time the mortality status of 137 patients were collected, of which 28 (20.4%) had died at the end of the study.

For both the 24 h urinary 5-HIAA and spot urinary 5-HIAA/cr tests survival rates decreased with increasing values in the respective initial tests. However, in both tests they did not become significant until 720 days follow up and it was only for the highest value groups. The initial 24 h urinary 5-HIAA group for values ≥100 had a 0.61 (CI 0.43–0.77) survival at 720 days compared to a survival rate of 0.86 (CI 0.74–0.94) for the ≤20 and 0.86 (CI 0.74–0.94) for the 21–99 value groups. Initial spot urinary 5-HIAA/cr patients with an initial value of ≥10 had a 720 day survival of 0.52 (CI 0.3–0.7) compared to a 0.92 (CI 0.80–0.97) survival for values ≤1 and a survival rate of 0.86 (CI 0.74–0.94) for the 2–9 group.

This data suggests that differing values for both 24 h urinary 5-HIAA and spot urinary 5-HIAA/cr tests may predict different survival rates at 2 years follow up in carcinoid patients.