Hyperparathyroidism is a type of thyroid disease. For the most part, hyperparathyroidism is a benign condition, but it can cause symptoms of hypothyroidism. It can be caused by a number of factors, including a lack of thyroid hormone. Hyperparathyroidism is a condition that affects about 1 in 20 people. It can result from a genetic defect or from a combination of two conditions. Hyperparathyroidism symptoms include: