Parathyroid Gland Disease
One of the most common disorders of the endocrine glands is called primary hyperparathyroidism (pHPT). The incidence of this condition increases with age and is more common in elderly women.
The parathyroid glands comprise four small structures that normally measure about 5mm in diameter and weigh only 30-50 mg. There are two glands on either side of the neck and they are located behind the much larger thyroid gland. The parathyroid glands release a hormone called parathyroid hormone (PTH) which maintains a normal blood level of calcium. Optimal levels of calcium are vital for the normal function of the nervous system and skeletal muscles. Adequate calcium is also required for normal blood clotting.
What is the cause of pHPT?
- Parathyroid adenoma: pHPT is most commonly caused by an increase in size and activity of one of the parathyroid glands. This enlarged gland is known as a parathyroid adenoma. The adenoma does not recognise or respond to the blood calcium level and constantly releases high levels of PTH. Often a parathyroid adenoma will be 20 times as large as a normal gland. In a few patients more than one parathyroid adenoma may be present.
- Parathyroid hyperplasia: in this condition several of the parathyroid glands increase in size and together release large amounts of PTH.
- Parathyroid Malignancy: one of the parathyroid glands enlarges and invades into the adjacent tissues. This occurs rarely in less than 1% of cases of pHPT.
What are the effects of pHPT?
- An increase of calcium in the blood level. If the calcium rises to very high levels you will experience excessive thirst and pass large amounts of urine. Dangerously high levels of blood calcium may occur but this is unusual.
- The high level of PTH will lead to increased release of calcium from the bones resulting in thinning of the bones (osteoporosis) and an increased risk of fractures. In severe cases bone pain will be present.
- A high level of calcium within the urine can cause kidney stones.
- High blood pressure and stomach ulcers are increased in patients suffering with pHPT.
- Some patients with pHPT feel tired, depressed and lack energy. These symptoms are frequently helped if the condition is cured.
How is pHPT diagnosed?
- Most patients will be diagnosed following routine blood tests.
- It is often detected in patients who are diagnosed with kidney stones.
- It is frequently diagnosed in patients investigated for osteoporosis.
How is pHPT investigated?
- A bone scan will be performed to assess whether there is any damage to the skeleton and determine the risk of future fractures.
- A 24hr collection of urine may be taken to measure the quantity of calcium excreted in the urine.
- A ultrasound examination of the neck will be performed to look for enlarged parathyroid glands.
- A radio-nucleotide scan of the neck known as a Sestimibi scan will be arranged to identify the site of any parathyroid glands showing increased activity.
When and how is pHPT treated?
- Conservative treatment – mild cases of pHPT with only marginal elevation of the blood calcium levels and no damage to the skeleton may be managed by clinic follow-up and regular blood tests. Most patients will be under the care of an endocrinologist. If the calcium level rises or complications develop then the patient will be referred for surgery.
- Surgery – patients who have a high calcium level, kidney stones, osteoporosis or symptoms such as lethargy and depression will be referred for surgical treatment.
The surgical procedure to remove abnormal parathyroid glands is called a parathyroidectomy. The nature of the operation recommended by the specialist surgeon will depend upon the results of the ultrasound and radio-nucleotide scans.
Minimal incision or minimal access parathyroidectomy. This procedure can be performed if the scans of the neck can accurately identify the site of the single abnormal gland. This operation is performed via a small incision on the side of the neck and the abnormal gland is excised. It is a very low risk simple procedure. Around 70% of patients with pHPT are suitable for this approach.
Parathyroid exploration. In patients with negative scans a collar incision across the lower neck is necessary. In this procedure the surgeon will carefully search for any abnormal glands which will be removed. This is not a major procedure and the wound will heal nicely with minimal scarring.
Results of surgery
About 95% of patients with pHPT will be cured with parathyroid surgery. Occasionally an operation will fail and the reasons why this may occur will be explained by your surgeon. Serious complications following parathyroid surgery are extremely rare in the hands of an experienced thyroid and parathyroid surgeon.
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