Surgery for Hyperparathyroidism

Hyperparathyroidism is a disorder characterised by the excess production of parathyroid hormone secondary to overactivity of the parathyroid glands. Primary hyperparathyroidism results from autonomous production of parathyroid hormone from abnormal parathyroid glands.

The vast majority of patients have a single adenoma. Approximately 10% of patients will have double adenomas and some rare cases have four-gland hyperplasia. Secondary hyperparathyroidism occurs due to excess parathyroid hormone levels from a physiological response to hypocalcaemia. This is found most commonly in chronic renal failure and vitamin D deficiency.

Tertiary hyperparathyroidism occurs when excess parathyroid hormone is secreted after longstanding secondary hyperparathyroidism. This often occurs in secondary hyperparathyroidism patients after renal transplantation. Hypercalcaemia that ensues causes a myriad of symptoms, the clinician must remember well “bones, stones, abdominal moans and psychic groans.”

Parathyroidectomy is the surgery one undergoes to remove one or more of the “rogue” parathyroid glands. Parathyroidectomy is indicated in all symptomatic patients with primary hyperparathyroidism. It is also indicated in asymptomatic patients with the following criteria:

1. Age < 50 years with serum calcium > 1mg/dl above normal limit

2. Urinary calcium excretion > 400mg/day

3. GFR  < 60mls/min

4. BMD – T score < -2.5 at any site and / or previous fracture fragility

5. Medical surveillance not desirable

6. Patient request

Parathyroidectomy is the only definitive treatment for primary hyperparathyroidism. Most patients with secondary and tertiary hyperparathyroidism are managed medically. The medically-refractory cases are referred for surgery which often requires removal of 3.5 glands. This is also the required surgery in cases of multiple endocrine neoplasia. Parathyroid carcinoma is exceedingly rare (0.5-1% of all cases of hyperparathyroidism). Surgery entails en-bloc resection with frozen section to ensure microscopically clear margins.

It is unusual for a patient to present to the surgeon with hyperparathyroidism. They are usually referred by the endocrinologist or nephrologist and must be managed in conjunction with their endocrinologist / specialist physician.

Prior practice of bilateral parathyroid exploration has given way to focused parathyroidectomy. This has become the standard of care. This entails pre-operative localisation with Sestamibi scanning +/- ultrasound and multiplanar imaging. Surgery involves a local neck incision and dissection to the location of the gland which is aided by intra-operative Mibi localisation. Once the gland is removed it is subjected to frozen section histology. We also employ intra-operative rapid parathyroid hormone assay which ensures biochemical resolution. The rapid assay has become particularly helpful in the redo cases. Intra-operative recurrent laryngeal nerve monitoring is standard.

Post-operative complications are rare in high volume surgical units. The recurrent laryngeal nerves are respected and monitored throughout the dissection. Transient neuropraxias may occur due to dissection and potential thermal spread from energy devices but these usually resolve within a few weeks. The expected post-operative hypocalcaemia will usually require transient calcium +/- Vitamin D supplementation. This is particularly challenging to manage in the 3.5 gland excision and careful follow up by the endocrinologist is warranted to prevent the development of symptomatic hypocalcaemia.

Due to the development of advanced pre-operative imaging and localisation techniques as well as utilisation of the rapid intra-operative parathyroid hormone assay, the procedure of parathyroidectomy has become a safe and successful procedure.