Hyperparathyroidism

Hyperparathyroidism is a disorder of excessive parathyroid hormone (PTH) secretion, leading to dysregulation of calcium and phosphate homeostasis. The condition is classified into three types based on mechanism.

Types:

• Primary HPT: Autonomous PTH secretion from parathyroid adenoma (85%), hyperplasia (10-15%), or rarely carcinoma (under 1%)
• Secondary HPT: Compensatory PTH elevation in response to chronic hypocalcemia (renal failure, vitamin D deficiency, malabsorption)
• Tertiary HPT: Autonomous PTH secretion developing after prolonged secondary HPT (typically post-renal transplant)

Parathyroid Hormone Physiology

PTH actions on calcium homeostasis:

Net result: Elevated serum calcium, reduced serum phosphate

Primary Hyperparathyroidism Pathogenesis

Secondary Hyperparathyroidism

Tertiary Hyperparathyroidism

Primary Hyperparathyroidism Presentation

Brown Tumors - Orthopaedic Manifestation

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Algorithm

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Primary Hyperparathyroidism - Surgical Indications

Surgical Options

Medical Management

Secondary Hyperparathyroidism Management

The topic repeatedly relies on the idea that an intraoperative PTH (IOPTH) "drop over 50% confirms cure", and this is a standard viva follow-up. Here is the underlying logic.

Why it works — PTH half-life: Intact PTH has a very short circulating half-life of roughly 2 to 4 minutes because it is rapidly cleared by the liver and kidney. Once the last hyperfunctioning gland (adenoma) is removed, the previously suppressed normal glands cannot yet respond, so serum PTH falls steeply within minutes. This kinetic property is what makes real-time intraoperative confirmation of cure possible and is the enabling technology behind focused/minimally invasive parathyroidectomy.

Hungry bone syndrome (HBS) is named in the postoperative safety alert and is an explicit viva follow-up ("What is hungry bone syndrome and how do you manage it?"), so it warrants its own account. It is the orthopaedically important metabolic pitfall of the immediate post-parathyroidectomy period.

Global Epidemiology

• Prevalence approximately 1-7 per 1000 adults; among the most common endocrine disorders after diabetes and thyroid disease.
• Female predominance roughly 3:1, peaking in postmenopausal women (age 50-70).
• In high-income settings with routine biochemistry screening, most cases are asymptomatic and detected incidentally; in regions where calcium is not measured routinely, patients still present late with florid skeletal disease (brown tumours, fractures) and renal stones, so the classic "bones, stones, groans" picture remains common.
• Secondary HPT prevalence tracks the burden of chronic kidney disease and vitamin D deficiency, which is high across much of South Asia, the Middle East and parts of Africa.

Side-by-Side Guideline Comparison

Registry and Outcome Notes

• There is no implant registry for parathyroid surgery; outcome benchmarks come from national audit and high-volume series (cure rates 95-99%, permanent hypoparathyroidism and recurrent laryngeal nerve injury each typically under 1-3%).
• Surgeon and centre volume are the strongest determinants of cure and complication rates — a recurring theme across health systems.

High- vs Limited-Resource Practice Variation

• Well-resourced settings: incidental biochemical diagnosis, dual-modality localisation (sestamibi plus ultrasound, with 4D-CT for reoperation), minimally invasive parathyroidectomy with rapid intraoperative PTH, and day-case surgery.
• Limited-resource settings: later presentation with overt bone disease; localisation may rely on ultrasound alone; bilateral neck exploration remains a robust default when rapid PTH assays or nuclear imaging are unavailable; vitamin D repletion before surgery is essential to limit hungry bone syndrome.

• Normocalcaemic primary HPT — patients with consistently elevated PTH but persistently normal calcium (after excluding vitamin D deficiency, renal impairment and drugs). Whether and when to operate is unresolved; a proportion progress to classic hypercalcaemic disease.
• Surgery for mild/asymptomatic disease — the SIPH RCT shows a BMD benefit from surgery, but no randomised trial has yet shown a fracture-reduction benefit in mild disease, so the threshold for operating on patients who do not meet formal criteria remains debated.
• Non-classical (neurocognitive) symptoms — fatigue, low mood and cognitive complaints are common, but improvement after parathyroidectomy is inconsistent across studies, so these symptoms alone are a weak surgical indication.
• Localisation strategy — the optimal first-line imaging (ultrasound, sestamibi-SPECT, 4D-CT, or choline PET) varies by availability and expertise; negative imaging does NOT exclude an adenoma and should not deny a patient surgery by an experienced surgeon.
• Bilateral exploration vs focused surgery — focused MIP risks missing multigland disease; intraoperative PTH monitoring mitigates but does not eliminate this, and some centres still favour four-gland assessment.
• Cinacalcet's role — it lowers calcium but does not reliably improve BMD or cure disease, so it is reserved for patients unfit for or declining surgery rather than as an equivalent alternative.

Hyperparathyroidism presents in three forms: Primary (autonomous PTH secretion, usually from a single adenoma in 85% of cases), Secondary (compensatory PTH elevation from chronic renal failure or vitamin D deficiency), and Tertiary (autonomous hyperfunction after chronic secondary HPT). The classic clinical triad "Bones, Stones, Groans" describes skeletal manifestations (osteitis fibrosa cystica, brown tumors, subperiosteal resorption), renal calculi from hypercalciuria, and abdominal pain. Brown tumors are benign osteoclastic giant cell lesions (not malignant despite the name) that mimic metastases on imaging but resolve after parathyroidectomy. Biochemical diagnosis is key: elevated calcium WITH elevated PTH confirms primary HPT (malignancy causes elevated calcium with suppressed PTH). Surgical indications for primary HPT include: age under 50, calcium greater than 2.85 mmol/L, GFR less than 60, T-score less than -2.5, brown tumors, or renal stones—asymptomatic mild disease can be observed with monitoring.