| Type 1 |
| Primary hyperparathyroidism (>90 percent) |
| Pituitary tumors (10 to 20 percent) |
| Prolactinoma |
| Growth hormone-secreting |
| Corticotropin-secreting |
| Non-hormone-secreting |
| Enteropancreatic tumors (60 to 70 percent) |
| Gastrinoma (Zollinger-Ellison syndrome) |
| Insulinoma |
| Vasoactive-intestinal polypeptide-secreting |
| Glucagonoma |
| Pancreatic polypeptide-secreting |
| Non-hormone-secreting |
| Other |
