This includes the commonest underlying diagnosis: primary hyperparathyroidism, and all other causes of hypercalcaemia.

PTH results low or undetectable

In all cases of hypercalaemia with suppressed PTH, it is mandatory to perform serum and urine protein electrophoresis and a chest radiograph. Other investigations and further management will depend on the clinical findings and are listed in further investigations.

Where possible, remove offending drugs for example in milk alkali syndrome, or after psychiatric liaison for lithium use.

Start definitive treatment for thyrotoxicosis or Addison’s disease if appropriate.

PTH results normal or elevated

Calcium to creatinine clearance ratio <<0.01 and patient asymptomatic

This is consistent with a diagnosis of familial hypocalciuric hypercalcaemia. No further investigations or treatment are necessary. Family members should be informed about this diagnosis to prevent unnecessary investigations in the future.

Calcium to creatinine clearance ratio close to 0.01 and or possible symptoms

These results are inconclusive and have not fully excluded FHH. It may be worth repeating 24hr collection three times for both calcium and magnesium:creatinine clearance ratios. Alternatively, consider sequencing of the calcium sensing receptor.

Calcium to creatinine clearance ratio >>0.01

FHH is confidently excluded by the finding of raised urinary calcium excretion and an elevated calcium to creatinine clearance ratio.

Vitamin D deficiency detected <25ng/ml and calcium <3mmol/l

Vitamin D should be replaced by prescribing a pure vitamin D supplement before repeating the investigations and deciding on future management. Suitable formulations are 10,000 units ergocalciferol orally per week or 100,000 units intra-muscularly.

Confirmed primary hyperparathyroidism

Recommend high fluid intake and normal calcium diet in all patients

High calcium diets exacerbate hypercalcaemia. However, excluding calcium from the diet may also exacerbate hypercalcaemia as it may lead to further elevation of PTH and bony resorption.

Ensure all patients are not taking any interfering medications

Look specifically for calcium or vitamin D containing supplements or antacids.

Consider surgery

If the patient is suitable for and agreeable to surgery, arrange localising studies - neck ultrasound scan and MIBI.

Refer to a parathyroid surgeon for minimally invasive surgery.

If imaging fails to localise an adenoma, and the patient has not had previous neck surgery, consider bilateral neck exploration.

If imaging fails to localise an adenoma, and the patient is more complex, or has had previous neck surgery, consider selective sampling or further imaging with CT scanning.

Follow up post surgery

Arrange monitoring of serum calcium, urea and electrolytes three months post surgery and review results and histology. If calcium is within the normal range post operatively, discharge.

Conservative management

Surgery should be offered to all patients with primary hyperparathyroidism.

However, if the patient is asymptomatic with no complications, they may decline or be unfit or otherwise unsuitable for surgery. In this case, arrange six monthly monitoring of serum calcium. 

Patients with stable serum calcium which is below 2.85mmol/l may be discharged for regular monitoring by the GP.

Patients should be re-assessed if they develop new symptoms or complications, or their calcium rises, or they reconsider surgery.

Consider bisphosphonate or other treatment for osteoporosis

The best treatment for osteoporosis in hyperparathyroidism is surgery. However, standard drug treatment should be considered if the patient is not for surgery.

Consider urology referral for symptomatic renal colic

Renal colic should be managed in the usual way.

Consider Cinacalcit

This drug is not yet in wide use and is expensive. However, it has been shown to reduce serum calcium effectively and so should be considered in patients unfit for surgery. It's effects on long term outcomes and short term symptoms have not been fully evaluated.

Arrange long term six monthly monitoring of serum calcium

Unless the patient has undergone a surgical cure, long term monitoring (usually by their GP) should be arranged to allow early detection and treatment of complications.

Definitive treatment should be reconsidered if their clinical condition changes.

Emergency treatment of hypercalcaemia

Hypercalcaemia associated with acute renal failure, confusion, or other emergency features requires emergency treatment. Rapidly increasing and very high levels should also be treated immediately.

Fluid resuscitation with 0.9% saline is the first line of treatment. Four litres per 24 hours is usually sufficient to bring calcium levels down. Patients with unstable cardiac disease, or others who may not tolerate fluid resuscitation should be discussed with a nephrologist to consider dialysis. Urgent parathyroid surgery or treatment of underlying disease, such as malignancy or sarcoidosis, will also usually bring calcium levels down quickly.

If initial measures fail to control the hypercalcaemia, bisphosphonate infusion may be considered, after all initial investigations have been completed.