Hyperparathyroidism is a common disorder of calcium, phosphorus, and bone metabolism caused by increased circulating levels of parathyroid hormone (PTH) 

– PTH decreases urinary excretion of calcium and increases urinary excretion of phosphate.

-it is the most common disorder of parathyroid function

-it is categorized as primary, secondary, or tertiary depending on the etiology

-Causes: solitary parathyroid adenoma (85%), hyperplasia, multiple adenomas, carcinoma 

Primary hyperparathyroidism: 

-The most common cause of hypercalcemia 

-in the outpatient setting: Primary hyperparathyroidism 

-in the inpatient setting: Malignancy 

-It occurs at all ages, affects women more than men, most commonly in the seventh decade 

Secondary hyperparathyroidism: 

-PTH levels are elevated in response to chronic hypocalcemia

-Most common causes are chronic renal failure, vitamin D deficiency

Tertiary hyperparathyroidism: 

-Autonomous hypersecretion of PTH and hypercalcemia 

Symptoms & Signs 

-Classic description: “bones, stones, abdominal groans, psychic moans, with fatigue overtones.”

-Primary hyperparathyroidism is often asymptomatic 

General: Fatigue, weakness, irritability 

Psychiatric: Depression, dementia, and confusion

Cardiovascular: Hypertension, palpitations,prolonged P-R interval, shortened Q-T interval, bradyarrhythmias, heart block, asystole  

Gastrointestinal: Anorexia, nausea, vomiting, heartburn, peptic ulcer, weight loss, constipation, abdominal pain, pancreatitis 

Bone: osteoporosis, bone pain, osteitis fibrosa cystica 

Rheumatologic: arthralgia, myalgia, and gout

Neurological: Paresthesias, headaches, diminished deep tendon reflexes, insomnia, irritability 

Dermatologic: Pruritus 

Renal: Nephrolithiasis, polyuria, polydipsia, and renal failure 

Diagnosis 

1. Laboratory findings: Elevated serum calcium, ionized calcium; Elevated PTH; Low or low-normal phosphate levels; Elevated alkaline phosphatase

2.Other tests: Radiographs: Extensive areas of demineralization with areas of increased bone density (“Salt and pepper” skull); Electrocardiography & echocardiography

Treatment 

Medications: Calcium mimetics such as Cinacalcet, Bisphosphonates, Denosumab, Vitamin D and vitamin D analogs

Surgical treatment: Parathyroidectomy