Causes of high diastolic blood pressure include medical conditions such as hypothyroidism, coarctation and adrenal tumors, according to the American Academy of Family Physicians. High diastolic blood pressure usually has no known cause and tends to run in families.
Hypothyroidism is a condition that occurs when there is a lack of thyroid hormone produced by the thyroid gland, notes Healthline. The most common causes of the condition are autoimmune diseases, surgical removal of the thyroid and radiation exposure. Because the body needs thyroid hormone to maintain healthy cells and muscles, hypothyroidism can lead to symptoms such as fatigue, constipation and brittle hair.
Coarctation of the aorta occurs when the aorta narrows as a result of a birth defect, according to MedlinePlus. The cause of the birth defect is unknown, but it is common in people who have genetic disorders such as Turner syndrome. Coarctation of the aorta makes it hard for blood to pass through the artery, leading to symptoms such as cold feet, failure to thrive and chest pain.
Adrenal tumors are abnormal growths on the adrenal glands that have no known cause, explains Dartmouth-Hitchcock. Most adrenal tumors are benign and cause no symptoms. However, some tumors can increase hormone production, leading to symptoms such as high blood pressure, obesity, hair growth and panic attacks. Cancerous tumors cause pain, weight loss and a feeling of fullness.