If the 5-HIAA test misses up to 50% of carcinoid tumors, does this refer to both symptomatic & asymptomatic carcinoid tumors?

Urine 5-HIAA will correctly diagnose almost all midgut carcinoid tumors causing carcinoid syndrome but only 1/2 of foregut carcinoids causing an endocrine syndrome and almost none of the hindgut carcinoid (which rarely  cause any endocrine syndrome even when metastatic). Therefore, the combined use of other neuroendocrine  markers (blood serotonin and chromogranin A) should also be used in diagnosis and surveillace/follow-up of carcinoid.