FFinalistSouthampton · 2027
Endocrine
AKT · Endocrine/Calcium, bone & parathyroid

Primary hyperparathyroidism

Autonomous PTH excess (parathyroid adenoma) → hypercalcaemia

Overview

Autonomous overproduction of parathyroid hormone, usually from a single parathyroid adenoma (rarely hyperplasia/carcinoma; part of MEN1/2a). Causes hypercalcaemia with an inappropriately normal or raised PTH. Often asymptomatic (found on a calcium check); symptoms are 'bones, stones, abdominal groans and psychic moans'. Parathyroidectomy is curative.

Recognise

  • Often asymptomatic (incidental hypercalcaemia)
  • 'Stones' (renal calculi, nephrocalcinosis), 'bones' (osteitis fibrosa cystica, osteoporosis), 'abdominal groans' (constipation, peptic ulcer, pancreatitis), 'psychic moans' (depression, confusion)
  • Polyuria/polydipsia, fatigue; biochemistry: high calcium, LOW phosphate, raised/inappropriately-normal PTH

Red flags

  • Severe hypercalcaemia (>3.5) or hypercalcaemic crisis (confusion, dehydration, arrhythmia) → emergency (IV fluids ± bisphosphonate)
  • Part of MEN1/MEN2a → screen for associated tumours

Differentials & how to tell them apart

Hypercalcaemia of malignancyPTH SUPPRESSED (PTHrP-mediated or bony mets); usually unwell with known cancer — the key contrast
Familial hypocalciuric hypercalcaemia (FHH)mild hypercalcaemia with LOW urine calcium and a benign family history — do NOT operate
Tertiary hyperparathyroidismautonomous PTH after long-standing CKD/secondary hyperparathyroidism
Vitamin D toxicity / sarcoidosis / drugsPTH suppressed; specific context

Investigations

Calcium (high) + PTH (raised or inappropriately normal) + phosphate (low) + raised urine calcium (excludes FHH). Vitamin D, renal function; imaging (sestamibi/ultrasound) to localise the adenoma; DXA; renal imaging for stones.

Management

Parathyroidectomy (cinacalcet if surgery unsuitable); hydrate severe hypercalcaemia

  1. 1Confirm high calcium with raised/inappropriately-normal PTH and low phosphate; check urine calcium to exclude FHH. Surgery (parathyroidectomy) for symptomatic disease, or asymptomatic disease meeting criteria (younger age, very high calcium, renal/bone involvement).Gate: Distinguish from hypercalcaemia of MALIGNANCY (PTH SUPPRESSED) and from FHH (low urine calcium — must NOT be operated on); the PTH level and urine calcium are the discriminators
  2. 2Asymptomatic not meeting surgical criteria → monitor (calcium, renal, DXA), ensure hydration, vitamin D replete; cinacalcet if surgery declined/unsuitable.
Parathyroidectomy — definitive/curative for symptomatic or qualifying disease
Cinacalcet (calcimimetic) — medical control if surgery unsuitable
IV fluids ± bisphosphonate (acute hypercalcaemia) — for severe/symptomatic hypercalcaemia

Key points

High calcium + raised/normal PTH + low phosphate = primary hyperparathyroidism (curable by surgery). Malignancy SUPPRESSES PTH; FHH has low urine calcium (don't operate). Bones, stones, groans, moans.

Monitor & prognosis

Calcium, renal function, DXA; post-op cure.

Cured by surgery.

Source: Society for Endocrinology; NICE NG132