Primary hyperparathyroidism
Primary hyperparathyroidism is autonomous PTH oversecretion, most often from a solitary parathyroid adenoma, producing hypercalcemia with an elevated or inappropriately normal PTH and low or low-normal phosphorus. Most patients are asymptomatic and identified on routine labs; parathyroidectomy is curative and is first-line for symptomatic disease or when specific biochemical, skeletal, or renal criteria are met, while observation with annual monitoring suffices for mild, asymptomatic disease.
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What this article covers
- Overview
Definition: primary hyperparathyroidism is autonomous, excessive secretion of parathyroid hormone (PTH) from one or more parathyroid glands, causing hypercalcemia independent of the normal calcium-sensing feedback loop.
- Epidemiology
Most common cause of hypercalcemia in ambulatory patients.
- Risk factors
Female sex and age over 50 years: the demographic with the highest incidence.
- Pathophysiology
Loss of normal calcium feedback: an adenoma or hyperplastic gland secretes PTH autonomously, no longer suppressing appropriately as serum calcium rises.
- Clinical features
Usually asymptomatic: identified on routine chemistry panels; when hypercalcemia is symptomatic, findings follow the "stones, bones, groans, and psychiatric overtones" pattern.
- Differential diagnosis
Familial hypocalciuric hypercalcemia (FHH): mild lifelong hypercalcemia with an inappropriately normal or elevated PTH but a 24-hour urine calcium-creatinine clearance ratio below 0.01, unlike the…
- Diagnosis
The clinching diagnostic basis is biochemical, not a formal scoring criteria set: hypercalcemia with an elevated or inappropriately normal PTH, since a normally functioning parathyroid gland would…
- Management
First, determine if the patient is symptomatic or meets surgical criteria; if so, parathyroidectomy is the treatment of choice (about 95 percent cure rate, less than 1 percent complication rate with…
- Complications
Hypercalcemia and its acute sequelae: nephrolithiasis, nephrocalcinosis, acute kidney injury, and altered mental status.
- Prognosis
Excellent after successful parathyroidectomy: surgery cures about 95 percent of patients, with BMD improvement, especially at the spine, seen by 1 year postoperatively.
- Prevention
Annual monitoring in patients who defer surgery: serum calcium and creatinine every year, BMD every 2 years, and spine imaging if significant height loss or back pain develops.
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Related articles
- Hypercalcemia
Hypercalcemia is an elevated serum calcium concentration, most often caused by primary hyperparathyroidism in ambulatory patients or malignancy in hospitalized patients. Mild disease requires only treatment of the underlying cause, while severe or symptomatic hypercalcemia is treated with aggressive IV isotonic fluids, followed by an IV bisphosphonate or denosumab for sustained control and subcutaneous calcitonin as a rapid but short-lived bridge.
- Secondary hyperparathyroidism
Secondary hyperparathyroidism is an appropriate, physiologic rise in parathyroid hormone driven by hypocalcemia or impaired vitamin D activation, most commonly from chronic kidney disease and less often from vitamin D deficiency or malabsorption. Management targets the underlying stimulus with dietary phosphorus restriction, phosphate binders, vitamin D repletion or active vitamin D analogs, and calcimimetics, reserving parathyroidectomy for disease refractory to medical therapy.
- Tertiary hyperparathyroidism
Tertiary hyperparathyroidism is autonomous parathyroid hormone hypersecretion that develops after long-standing, poorly controlled secondary hyperparathyroidism, most often in end-stage kidney disease, causing eucalcemia or hypercalcemia despite hyperplastic glands that no longer respond to normal feedback. Cinacalcet is first-line medical therapy, and subtotal or total parathyroidectomy with autotransplantation is reserved for disease refractory to medical management or a markedly elevated PTH.
- Familial hypocalciuric hypercalcemia
Familial hypocalciuric hypercalcemia is an autosomal dominant, lifelong, asymptomatic hypercalcemia caused by an inactivating mutation of the calcium-sensing receptor, which raises the parathyroid hormone and renal calcium reabsorption set point. The clinching test is a 24-hour urine calcium-creatinine clearance ratio below 0.01, and management is reassurance and family screening, since parathyroidectomy does not correct the calcium and is not indicated.
- Multiple endocrine neoplasia type 1
Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant tumor-suppressor syndrome causing parathyroid, pancreatic, and pituitary tumors, the '3 Ps.' First-line treatment is organ-specific: parathyroidectomy for hyperparathyroidism, dopamine agonists for prolactinoma, and surgical resection or acid suppression for pancreatic neuroendocrine tumors.
- Osteoporosis
Osteoporosis is low bone strength that raises fragility fracture risk, diagnosed by a hip or spine T-score of -2.5 or less or by a fragility fracture itself. First-line treatment is an oral bisphosphonate, alendronate or risedronate, alongside adequate calcium and vitamin D intake.