Indications for surgery
Once the diagnosis has been confirmed and the parathyroid adenoma hopefully successfully localised with the scans, the treatment of choice is a minimally invasive parathyroidectomy.
Surgical removal of the abnormal parathyroid gland(s) is the only way to successfully cure hyperparathyroidism.
The advent of accurate preoperative localisation, minimally invasive surgery and the use of local anaesthetic have made surgical indications more flexible.
There are guidelines for who should have surgery, issued by the US National Institute of Health, although in practice there are few patients who are unsuitable for surgery and most patients will benefit from returning their calcium levels to normal.
Accordng to the NIH, after successful parathyroid surgery, bone density improves, fracture incidence is reduced (cohort studies), kidney stones are reduced in frequency among those with a history of renal stones, and, although not confirmed by randomised clinical trials, there may well be improvements in some neurocognitive elements. With advances in the effectiveness and safety of surgical techniques, particularly in the hands of expert parathyroid surgeons, the decision to remove the abnormal parathyroid tissue is bolstered by added confidence of its success.
Furthermore, improvements in a variety of preoperative imaging modalities have given the parathyroid surgeon a road map that is in general very reliable. Imaging is used as an aide to surgery, but not for diagnostic purposes.
Fig.1: Min. invasive parathyroidectomy
Minimally invasive parathyroidectomy has a 95-98% success rate in curing the disease in experienced hands, and 95% of patients will notice an improvement in symptoms (even when not readily apparent before surgery) over the long term.
In contrast, the success rate for surgeons who perform fewer than 10 parathyroidectomies a year is only 70%.
The recommended NIH guidelines (2014) have recently been updated with a much stronger emphasis on assessment of the skeletal and renal systems, the main targets affected by primary hyperparathyroidism.
These guidelines recommend surgery for the following groups of patients:
- all patients aged < 50 years
- symptomatic hypercalcaemia in all age groups
- any suggestion of parathyroid cancer
- in asymptomatic patients:
- hypercalcaemia > 0.25 mmol/l above normal in all age groups
- deterioration in skeletal status by DXA scan (T score <-2.5, or vertebral fracture)
- deterioration in renal function (creatinine clearance <60ml/min, 24 hour urine calcium >10mmol/day, or presence of renal stones or nephrocalcinosis)
- any patient where medical surveillance is not possible or desired
Surgical options
In most cases, where there is a single parathyroid adenoma which has been localised before operation, minimally invasive focused parathyroidectomy (MIP) is the ideal operation (Fig. 1). This is possible in about 75-80% of cases, and there is no evidence that outcomes are improved by any operative adjuncts, such as radio-guided surgery, intraoperative PTH measurement or using an endoscope for visualisation.
In the 20% of patients who cannot be localised and for those with parathyroid hyperplasia, a traditional four gland exploration is done through a slightly larger incision, and results in either:
- Parathyroidectomy - removal of a single gland
- Subtotal parathyroidectomy - removal of more than one gland, leaving normal gland(s) behind
- Total parathyroidectomy - removal of all glands
- Total parathyroidectomy and autotransplantation - removal of all glands and transplantation of small amount of normal gland into forearm or neck
Which operation is the correct one depends on the disease found in the neck at surgery. Details of the surgery can be found on the webpages about Parathyroid surgery.
Medical options
There is no medical treatment that will cure hyperparathyroidism, but there are drug treatments available that will reduce or control calcium levels in those in whom surgery is not possible (a rare event nowadays).
Fig.1: Bisphosphanate therapyThere are some novel treatments that involve the calcium sensing receptor (CaR) of the parathyroid gland that are effective in lowering the calcium level. If the patient is unfit for surgery then long term use of oestrogens or bisphosphonates is the treatment of choice, especially in patients with reduced bone density.
Of the two agents bisphosphonates are preferred because of the long term risks of oestrogens on the cardiovascular system. Long term bisphosphonate therapy may increase bone strength in untreated primary hyperparathyroidism, but there is no direct evidence to confirm this finding.
There is no doubt that in cases where these agents are not effective and surgery is contraindicated then cinacalcet is the treatment of choice.
Cinacalcet no longer has PBS approval in Australia for secondary parathyroid disease or parathyroid cancer. It has been approved in the UK for use in selected patients with primary hyperparathyroidism (but not in Australia). It has been shown in patients with primary hyperparathyroidism in a double-blind, randomised controlled trial to cause a fall in the serum calcium in a dose dependant manner, with return to normal of the serum PTH as well. At this stage however it has not been shown to significantly increase bone density.
Summary
There are medical treatments available for hyperparathyroidism, but surgery remains by far the treatment of choice. With the use of local anaesthetic and minimally invasive surgical techniques there are very few patients unsuitable for surgery. Medical treatments must be taken life-long, are expensive and not without side effects.
It is important to remember that:
- It is never normal to have a raised serum calcium
- Almost all patients with hyperparathyroidism will have a single abnormal gland
- The abnormal gland is a tumour (almost always benign – not cancer)
- Surgical experience is vital for a successful outcome without complications
- Once the abnormal gland has been removed the calcium will return to normal within hours
- Up to 95% of patients will notice an improvement in symptoms after surgery