This is the surgical disease of the calcium circuit. A single adenoma secretes PTH without reference to the calcium it is supposed to be defending, and the loop that would normally switch it off no longer works. Everything that follows — the high calcium, the low phosphate, the stones, the thin bones — is that one failure played out.
What is actually there when the neck is opened
| Finding | How often | What it means for the operation |
|---|---|---|
| Single adenoma | About 85% | One gland to find and remove — a focused operation is possible |
| Four-gland hyperplasia | 10–15% | All four glands involved; think MEN 1 or MEN 2A, especially in a young patient |
| Double adenoma | About 4% | The reason intra-operative PTH monitoring exists, and the commonest cause of persistent disease |
| Carcinoma | Under 1% | Very high calcium, a palpable mass — needs en-bloc resection |
Eighty-five per cent of the disease is one gland. The value of knowing the other fifteen per cent is that it explains every failed operation.
Confirming the diagnosis
- A raised corrected calcium on two occasions
- PTH raised, or inappropriately normal
- Phosphate low or low-normal
- Vitamin D replete before any judgement is made — deficiency distorts the PTH
- A 24-hour urine calcium, to exclude familial hypocalciuric hypercalcaemia
Exclude FHH before anyone is listed
Familial hypocalciuric hypercalcaemia is a benign, lifelong, autosomal dominant condition caused by an inactivating mutation of the calcium-sensing receptor. The calcium is high and the PTH is normal or mildly raised, so the biochemistry looks like mild primary hyperparathyroidism — but the urine calcium is low (under 100 mg/24 h, with a calcium–creatinine clearance ratio below 0.01). These patients do not benefit from surgery and should never have their necks explored.
Who needs an operation
Every symptomatic patient is offered parathyroidectomy. For the asymptomatic patient, any one of the following is an indication:
| Domain | Threshold |
|---|---|
| Age | Under 50 years |
| Calcium | More than 1.0 mg/dL above the upper limit of normal |
| Skeleton | T-score of −2.5 or lower at any site, or a vertebral fracture |
| Kidney | eGFR under 60 mL/min, stones or nephrocalcinosis, or urine calcium above 400 mg/24 h |
The question behind the question
Why operate on someone with no symptoms? — because the end-organ damage is silent. Cortical bone loss and renal impairment progress without the patient noticing, and both are arrested by a forty-minute operation with a cure rate above 95%.
Finding it, and taking it out
Imaging is planning, not diagnosis. The decision to operate has already been made in the laboratory.
- Ultrasound — no radiation, cheap, available, and it shows the thyroid at the same time, which matters because a coexisting nodule changes the operation. Blind to mediastinal glands.
- Sestamibi SPECT/CT — functional: a mitochondria-rich adenoma retains the tracer. It finds ectopic and mediastinal glands that ultrasound cannot. Less reliable in hyperplasia.
- 4D-CT — for discordant or negative first-line imaging and for re-operative necks. Higher radiation dose, so not a first test.
Concordant ultrasound and sestamibi earn the patient a focused, minimally invasive parathyroidectomy. Discordant or negative imaging means a four-gland bilateral exploration. Cure rates are 95–98% in experienced hands, and selected patients go home the same day.
What can go wrong
- Recurrent laryngeal nerve injury — hoarseness; check the cords if symptomatic
- Hypocalcaemia — transient, or from hungry bone syndrome
- Persistent disease (under six months) — a missed second adenoma or an ectopic gland
- Recurrent disease (after six months) — reconsider MEN, hyperplasia or carcinoma
- Haematoma — the airway emergency of any neck operation
Hungry bone syndrome
After a long-standing severe hyperparathyroidism is cured, a skeleton that has been dissolving for years suddenly starts rebuilding, and it strips calcium, phosphate and magnesium out of the plasma. Expect it when the preoperative calcium and alkaline phosphatase were both high and the adenoma was large. The hypocalcaemia is profound, prolonged and needs large doses of calcium and active vitamin D. It is told apart from surgical hypoparathyroidism by the phosphate: in hungry bone the phosphate is low; in hypoparathyroidism it is high.
If the patient is not operated on
Annual calcium and creatinine, and a DEXA every one to two years. Keep them hydrated, keep them vitamin D replete — deficiency makes the hyperparathyroidism worse, not better — avoid thiazides, and do not restrict dietary calcium.