胰脏 and
胰腺 (yíxiàn) both mean 'pancreas' and are interchangeable in everyday and journalistic use;
胰腺 is slightly more standard in mainland medical writing (e.g.
胰腺癌 'pancreatic cancer'), while
胰脏 is more common in Taiwan and older texts. The pancreatic hormone is
胰岛素 (yídǎosù, insulin).
