The over production of parathormone by the parathyroid glands. Usually secondary to an adenoma (an unregulated glandular tumour that produces parathormone in an increased quantity). Laboratory studies show an elevated calcium in the blood. most patients are without symptoms. Symptoms in more advanced cases include lethargy, confusion, nausea, bone pain and weakness. Findings include hypertension and slow heart rate. Complications include pancreatitis, peptic ulcer disease and kidney stones.