PET scan can also be used to find the primary tumor site. Bronchoscopy with biopsy can performed if there is evidence of a pulmonary tumor. For patients with serotonin elevated 5x the upper limit of normal or more, an echocardiogram is recommended for evaluation of carcinoid heart disease. Differential diagnosis Other conditions similar to the carcinoid syndrome that should be considered include: Irritable Bowel Syndrome Celiac Disease Ogilvie Syndrome Treatment Treatment of the carcinoid syndrome is focused on controlling the proliferation of the primary tumor and symptomatic control of the symptoms with somatostatin analogues octreotide or lanreotide. These analogues can help control the growth of the tumor itself and the associated symptoms of the carcinoid syndrome. In patients whose symptoms are refractory to initial doses, increasing the dose or switching to another analogue pasireotide may be effective. In patients who continue to be refractory, mTOR inhibitors such as everolimus. The TPH inhibitor telotristat ethyl may be useful in controlling diarrhea associated with the carcinoid syndrome. Peptide directed radiotherapy (PRRT) is another alternative treatment for patients who failed somatostain analogue therapy. This method uses radioactive somatostatin analogues such as 177Lu-Dotatate or 90Y-Edotreotide to target tumor directly. These therapies are effective for metastatic disease but studies have been limited to about 6 month time periods. Cytoreductive surgery performed chemically with 131metaiodobenzylguanidine (131I-MIBG) may also control symptoms starting around 6-15 months post procedure and lasting as long as 39 months. There are also procedures that target the liver directly such as radiofrequency ablation or radioembolization that deliver targeted therapy directly to the liver through special catheters. This is especially useful for patients with liver metastases. Carcinoid heart disease The most important aspect of treating carcinoid heart disease is detecting its presence with echocardiography, likely with color doppler. Treatment consists of the same treatment as patients with heart failure with definitive treatment being surgical valve repair or replacement. Uncertainties Disease progression is difficult to ascertain because the disease can metastasize anywhere in the body and can be too small to identify with any current technology. Markers of the condition such as chromogranin-A are imperfect indicators of disease progression. Epidemiology The incidence of neuroendocrine tumors in the US lies somewhere from 2.7 to 4.3 per 100,000 people and appears to be increasing over time. The incidence of the carcinoid syndrome is about 0.27 per 100,000 people in the US, about 10% of all people with