Surgery for Signs and/ or Symptoms
Patients who have clear signs of hyperparathyroidism whether they are skeletal (fractures) or renal (stones) or symptomatic hypercalcaemia should have parathyroid surgery, unless there are medical or other contraindications. Areas of uncertainly relate to patients who have the asymptomatic and normocalcaemic forms of the disease.
Surgery in Asymptomatic Primary Hyperparathyroidism
Since surgery is curative when successful, patients and physicians can opt for surgery even if the patients do not meet guidelines that have been proposed for surgical management. Some patients find this to be an attractive option while others are inherently reluctant to consider surgery under almost any circumstances.
Over the past three decades, four international workshops on the management of asymptomatic primary hyperparathyroidism have periodically reviewed and updated the evidence that would argue either for a surgical or non- surgical management approach. The 4th International workshop offered the following recommendations. They are listed here and shown in Table 1:
1. Serum calcium concentration greater than 1 mg/ dl above the upper limit of normal;
2. a. BMD by DXA T score < - 2.5 at lumbar spine, total hip, fem oral neck, or distal third radius;
b. vertebral fracture by X- ray, CT, MRI, or vertebral fracture assessment (VFA)
c. evidence of a clinical fracture
3. a. estimated GFR (eGFR) < 60 cc/ min;
b. 24- hour urine for calcium >400 mg/ day ( > 10 mmol/ day) and increased stone risk by biochemical stone risk analysis;
c. nephrolithiasis or nephrocalcinosis by X- ray, ultrasound, or CT;
4. Age < 50.
Table1. Guidelines for parathyroid surgery in asymptomatic primary hyperparathyroidism. Surgery is also indicated in patients for whom medical surveillance is neither desired nor possible. If any one of these criteria are met, the patient is considered to be a candidate for parathyroid surgery
Any one of these criteria is sufficient to recommend surgery. These recommendations have not been updated recently, but we look forward to refinements and modifications based upon new data that have become available at the time of the next international conference.
It should be emphasized that these guidelines are not rules and, in fact, like many other guidelines, they are not based on strong evidence. Physicians and patients modify them according to the individual clinical situation. Some physicians feel that all patients with PHPT should undergo parathyroid surgery, as long as there are no contraindications. Some patients will resist surgery even though there are clear candidates and are strongly advised to have parathyroid surgery. Others will base their recommendations on other criteria.
Surgical Approach in Primary Hyperparathyroidism
A key dictum in this field is that parathyroid surgery should be undertaken by those who are experienced and highly skilled in the procedure. While this dictum has not changed, over the past several decades, the approach to parathyroid surgery has. Rather than full exploration of the neck with visualization of all four parathyroid glands, many centres perform a limited procedure when there is pre- intraoperative evidence for single gland disease and that at the time of surgery, there is intraoperative evidence for cure. This is ascertained by intraoperative measurement of the PTH level at baseline and 2, 5, and 10 minutes following the removal of the parathyroid adenoma. If the PTH level falls by greater than 50% into the normal range, the resected parathyroid adenoma is considered to be the only gland involved and the operation is ended. With successful preoperative localization, this operation can be performed by those skilled in the procedure under local anaesthesia and conscious sedation. The minimally invasive parathyroidectomy (MIP), performed in an ambulatory care hospital setting, is a shorter operation without general anaesthesia, and with fewer complications. If the intraoperative PTH level does not meet the criteria for success, namely it doesn’t fall by greater than 50% and/ or remains above normal, the operation is converted to a full neck exploration to seek other glands that are presumably overactive. Success rates for this procedure that generally does not require an overnight hospital stay are greater than 90%, similar to the outcome of the full neck exploration.
When the patient has multigland disease, a full exploration is necessary. Options are subtotal parathyroidectomy, consisting of removal of 3.5 glands, or total parathyroidectomy with trans plantation of parathyroid tissue slices into the forearm. If the auto transplantation is successful, the patient will re- establish normal homeostatic control of the serum calcium by this ectopically placed parathyroid tissue. It is important to recognize that the tissue trans planted is abnormal and, thus, could become overactive in time. In that eventuality, the forearm site is convenient because the tissue could be accessed and debulked. Some centres have cryopreservation facilities which can be very helpful should the initial graft not take. Lebastchi et al. have reported using the minimally invasive approach in multigland disease.
Surgery for Parathyroid cancer
The surgical approach to parathyroid cancer is total removal of all malignant tissue and local neck dissection, when indicated. Sometimes, it is not known whether all malignant tissue has been removed because local and distant metastases can appear years after resection. Parathyroid cancer is one of the unusual malignancies in which metastases, if surgically approachable, can be removed with satisfactory results than can be measured sometimes in years. Multiple therapeutic approaches along with resection of the metastases have also been associated with long- term survival.
