Tumors in the adrenal glands, located on top of the kidneys, can cause high blood pressure. The outer part of the adrenal glands, called the adrenal cortex, produces certain hormones. One of these hormones, aldosterone, helps to regulate blood pressure, according to the American Cancer Society.
Most tumors found on the adrenal cortex are benign. Typically, people who have these benign tumors, called adenomas, have no symptoms and are not aware that they have the tumors. In some cases though, an adenoma can cause the adrenal glands to produce excess aldosterone, which can lead to high blood pressure. Malignant tumors can also be found on the adrenal cortex, but they are much less likely to cause high blood pressure, states the American Cancer Society.