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This is a clinician-written, evidence-based summary aligned to the 2026 MLA Content Map. It is intended for medical students and junior doctors preparing for the UKMLA. Always cross-reference with NICE guidance, local protocols, and clinical judgement.
The Bottom Line
- Most commonly caused by a solitary parathyroid adenoma (~85%). Four-gland hyperplasia (~10%) and carcinoma (<1%)
- Diagnosis: raised albumin-adjusted calcium (≥2.6 mmol/L) + raised/inappropriately normal PTH
- Many patients are asymptomatic — detected incidentally. Symptomatic: "bones, stones, moans, groans" (osteoporosis, renal stones, depression, abdominal pain)
- Differentiate from familial hypocalciuric hypercalcaemia (FHH): urine calcium:creatinine clearance ratio
- Surgery (parathyroidectomy): if symptomatic, calcium ≥2.85, renal stones, osteoporosis, or age <50 (NICE NG132)
- Non-surgical: cinacalcet if surgery unsuitable. Monitor: annual calcium, renal function, DEXA
Overview
Primary hyperparathyroidism (PHPT) is a condition of excess parathyroid hormone (PTH) secretion from one or more parathyroid glands, independent of normal calcium homeostasis feedback. A solitary parathyroid adenoma is the cause in approximately 85% of cases, four-gland hyperplasia in ~10–15%, and parathyroid carcinoma in <1%. Excess PTH increases calcium reabsorption from kidneys, bone resorption (releasing calcium), and 1,25-dihydroxyvitamin D synthesis (increasing intestinal calcium absorption). This results in hypercalcaemia and hypophosphataemia. The classic mnemonic for symptoms is "bones, stones, abdominal moans, and psychic groans." PHPT is associated with MEN1 (hyperparathyroidism + pituitary adenoma + pancreatic tumour) and MEN2A.
Epidemiology
PHPT is the third most common endocrine disorder after diabetes and thyroid disease. Prevalence is approximately 1–3 per 1000 in the general population, rising to 2–3% in postmenopausal women. Female:male ratio approximately 3:1. Peak incidence at 50–60 years. Many cases are now detected incidentally through routine biochemistry (elevated calcium). Risk factors include: postmenopausal women, previous neck irradiation, lithium therapy, and familial syndromes (MEN1, MEN2A, hyperparathyroidism-jaw tumour syndrome).
Clinical Features
Symptoms
Many patients are asymptomatic — detected on routine bloods
Fatigue, malaise, low mood, cognitive impairment ("psychic groans")
Bone/joint pain, osteoporosis, fragility fractures ("bones")
Renal colic, recurrent kidney stones ("stones")
Abdominal pain, constipation, nausea, peptic ulcer ("abdominal moans")
Polyuria and polydipsia (nephrogenic DI from hypercalcaemia)
Muscle weakness
Signs
Often no specific signs — diagnosis is biochemical
Rarely: palpable neck lump (if very large adenoma or carcinoma)
Dehydration (from polyuria)
Band keratopathy (calcium deposition in cornea — rare, seen on slit lamp)
Shortened QT interval on ECG
Investigations
First-line
Albumin-adjusted serum calciumElevated ≥2.6 mmol/L — repeat to confirm on at least 2 occasions (NICE NG132)
Serum PTHElevated or inappropriately normal in context of hypercalcaemia. Low PTH with hypercalcaemia suggests alternative cause (malignancy)
Second-line
Serum phosphateLow (PTH promotes renal phosphate excretion)
Vitamin D (25-OH)Assess and correct deficiency — may exacerbate bone disease and mask severity of hypercalcaemia
Urine calcium:creatinine clearance ratioDifferentiates PHPT from familial hypocalciuric hypercalcaemia (FHH). Low ratio (<0.01) = FHH. High ratio = PHPT
eGFRAssess renal function — hypercalcaemia causes nephrocalcinosis and CKD
DEXA scanAssess bone mineral density — osteoporosis is an indication for surgery
Specialist
Sestamibi-technetium subtraction scanPre-operative localisation of adenoma — identifies abnormal parathyroid tissue
Neck USSLocalise adenoma — combined with sestamibi for optimal pre-operative planning. Maximum 2 imaging modalities before surgery (NICE NG132)
Renal USS or CT KUBAssess for nephrolithiasis and nephrocalcinosis
1
Indications for parathyroidectomy
- Symptoms of hypercalcaemia (thirst, polyuria, constipation)
- End-organ disease: renal stones, fragility fractures, osteoporosis
- Albumin-adjusted calcium ≥2.85 mmol/L
- Age <50 years (higher long-term complication risk)
- eGFR <60 mL/min
- Surgery is curative in >95% — focused parathyroidectomy (minimally invasive) if localised single adenoma
2
Non-surgical management
- If surgery declined, unsuccessful, or unsuitable
- Cinacalcet (calcimimetic): reduces PTH secretion and calcium. Consider if calcium ≥2.85 with symptoms or ≥3.0 mmol/L
- Bisphosphonate (alendronate): to reduce fracture risk if osteoporosis — does NOT treat the underlying disease
- Adequate hydration (≥2 L/day), avoid dehydration
- Correct vitamin D deficiency (cautiously — monitor calcium)
3
Monitoring (all patients)
- Annual albumin-adjusted calcium, renal function
- DEXA scan as indicated for osteoporosis monitoring
- Post-surgery: check calcium within 24 hours — risk of hypocalcaemia (hungry bone syndrome)
- If successful surgery: annual calcium check long-term
Complications
- Osteoporosis and fractures: PTH-driven bone resorption — cortical bone affected more than trabecular. DEXA at diagnosis
- Nephrolithiasis and nephrocalcinosis: Hypercalciuria leads to calcium-containing renal stones (calcium oxalate/phosphate)
- Renal impairment: Chronic hypercalcaemia → nephrocalcinosis → CKD
- Cardiovascular: Hypercalcaemia associated with hypertension, LVH, shortened QT interval
- Pancreatitis: Hypercalcaemia is a rare but recognised cause of acute pancreatitis
- Peptic ulcer disease: Calcium stimulates gastrin secretion
- Post-operative hypocalcaemia (hungry bone syndrome): Rapid calcium flux into demineralised bones after parathyroidectomy — can cause severe symptomatic hypocalcaemia
UKMLA Exam Tips
- 1Raised calcium + raised PTH = primary hyperparathyroidism. Raised calcium + LOW PTH = non-PTH mediated (malignancy, sarcoidosis, vitamin D excess)
- 2"Bones, stones, abdominal moans, psychic groans" — classic mnemonic for PHPT symptoms
- 3FHH mimics PHPT biochemically — differentiate with urine calcium:creatinine clearance ratio. FHH = benign, no surgery needed
- 4MEN1: hyperparathyroidism + pituitary tumour + pancreatic tumour. Consider in young patients or multigland disease
- 5Cinacalcet: lowers calcium but does NOT prevent bone loss or renal complications. Surgery is definitive
- 6Post-parathyroidectomy: check calcium urgently. Hungry bone syndrome = severe hypocalcaemia as calcium re-enters bone
- 7Low phosphate in PHPT — useful discriminator. In malignant hypercalcaemia, phosphate is often normal or high
practicetest your knowledge on hyperparathyroidismApply what you've learnt with UKMLA-style questions from the iatroX Q-Bank — endocrine and beyond.
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