Primary hyperparathyroidism

Primary hyperparathyroidism 

Updated: 02/05/2024

© Jun Wang, MD, PhD

Definition

• Autonomous overproduction of parathyroid hormone
  

General features

• More common in women; usually age 50+
• NO evidence of prior parathyroid stimulation by renal or intestinal disease
• Most common cause: Adenoma
• Other causes: parathyroid hyperplasia and carcinoma

Key pathogenesis

• Autonomous overproduction of parathyroid hormone
• Subsequent activation of osteoclast

Clinical presentations

• May be asymptomatic
• Incidental finding of hypercalcemia
• Associated with hypercalcemia and excessive calcium resorption
• Bones: Osteoporosis, osteitis fibrosa cystica (brown tumor)
• Stones: Renal calcium stones, nephrocalcinosis
• Abdominal groans: Nausea, peptic ulcers (associated with high serum gastrin caused by hypercalcemia), constipation, pancreatitis, gallstones
• Psychic moans: Depression, lethargy, seizures
• Others: Proximal myopathy, Weakness, fatigue, calcifications

Key laboratory findings

• Hypercalcemia, although may be normocalcemic
• Inappropriately elevated levels of PTH
• Low serum phosphorus, high serum alkaline phosphatase, high urine calcium and phosphorus
• If low urine calcium but hypercalcemia, consider familial hypocalciuric hypercalcemia
• Calcium sensing receptor mutation
• Reduced sensitivity to serum calcium
• Higher level of serum calcium to suppress PTH secretion
• Low excretion faction of calcium, causing low urine calcium 
• Usually asymptomatic, but may present with non specific symptoms, including fatigue, polyuria, polydipsia, and abnormal renal function
  

Key radiologic features

• Increased bone absorption
• Osteoporosis

Osteitis fibrosa cystica

• Solitary or multiple
• Large lytic lesion resembling bone tumor
• Usually starts from fingers, facial bones, ribs, and pelvis
• Well-defined radiolucent bone lesions
• Brown due to hemorrhage
• Microscopic: Increased osteoclasts with interstitial hemorrhage, hemosiderin, microfractures, ingrowth of vascularized fibrous tissue with fibroblasts

Treatment

• Surgery

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