Introduction

Though many are aware of the existence of the thyroid, a gland responsible for the regulation of organ and cellular function, few are familiar with four small glands that reside just behind the thyroid, called the parathyroid glands, whose function, though completely distinct from the thyroid, is no less important.

The parathyroid glands produce parathyroid hormone, required for the precise regulation of blood calcium, which in turn ensures the normal function of many organ systems as well. Indeed abnormally high parathyroid hormone levels, a condition called hyperparathyroidism can cause debilitating symptoms more severe, and more morbid than problems associated with thyroid hormone disorders.


Symptoms of hyperparathyroidism include:

          Ureteric colic and urinary symptoms from kidney stones
          Bone pain and fractures from decreased bone mineral density and osteoporosis
          Abdominal pain from stomach ulcers and inflammation of the pancreas
          Neurological symptoms including fatigue, poor concentration and depression


The common mnemonic for hyperparathyroidism is a disease of "…stones, bones, groans and moans…" alluding to the symptoms typically associated with it.

Most patients we see today, however, are fortunately asymptomatic or have very mild symptoms. This is because with greater health awareness, many patients are diagnosed with hyperparathyroidism when blood calcium analyses, done as part of a routine health screen, are discovered to be abnormal before symptoms have appeared.


Causes & Consequences

The most common cause of hyperparathyroidism is from a parathyroid adenoma, a benign tumor of one of the four parathyroid glands that secretes excess parathyroid hormone. This solitary parathyroid adenoma accounts for 85% of cases of hyperparathyroidism. In the remaining 10 – 15% of cases the excess hormone production comes from two or four abnormal glands, called double adenomas and parathyroid hyperplasia respectively. Parathyroid cancer as a cause of hyperparathyroidism is exceedingly rare.

The abnormally high blood calcium levels cause the development of:

          Kidney stones from elevated urine calcium levels
          Osteoporosis from excessive calcium absorption from bones, predisposing to easy bone fractures
          Stomach ulcers and acute inflammation of the pancreas
          Neurological symptoms, particularly fatigue and depression
          Abnormal cardiac rhythm and cardiovascular disease


Treatment

Surgery is the definitive treatment for hyperparathyroidism.

Successful removal of the diseased parathyroid gland cures the patient of the disease, and reverses many of the preceding harmful effects of excess circulating parathyroid hormone.

Three decades ago, no preoperative investigations were performed to localize the diseased parathyroid gland, and the parathyroid surgeon was required explore all four glands, identify and remove the abnormal one. The dictum then was "…the only localization required is to localize a good parathyroid surgeon…" Identifying an experienced surgeon was essential as parathyroid glands are very small, about half the size of a grain of rice, and occasionally are abnormally located in other regions of the neck instead of behind the thyroid gland.

These days, preoperative localization of the diseased parathyroid gland is possible with two simple but very accurate investigations, a Sestamibi scan and neck ultrasound. If the parathyroid adenoma is precisely located, the surgeon can perform what is known as a MINIMALLY INVASIVE PARATHYROIDECTOMY, removal of the diseased gland through a small 2 cm incision in the neck. Identifying a surgeon experienced in parathyroid surgery is no less important today, however, as in the event that the scans prove inconclusive or inaccurate, the surgeons’ experience in locating all four parathyroid glands, identifying the abnormal one and removing it carefully is still paramount.

Parathyroid surgery is very safe, and as for thyroid surgery, risk of injury to the recurrent laryngeal nerve (the nerve to the voice box) is exceedingly low at less than 1% if performed by surgeons experienced in parathyroid surgery. Recovery is quick as well, with most patients staying just one night after surgery, and discharged well the next day.

Following successful surgery, kidney stones do not recur, bone density improves and fracture rates decline, cognitive function improves and mortality from cardiovascular disease is reduced.

Interestingly, many patients with hyperparathyroidism who were supposedly “asymptomatic” prior to surgery become miraculously better, being cured of many subtle symptoms like weakness, fatigue, bone ache and poor concentration that they did not realize existed, and were related to excess circulating parathyroid hormone and high blood calcium.

The Thyroid Head & Neck Surgery Centre