Parathyroid adenoma

Question 1

Define a parathyroid adenoma.

Answer 1

Benign tumour of the parathyroid gland.

Question 2

A parathyroid adenoma is the most common cause of which condition?

Answer 2

Hyperparathyroidism.

Question 3

What is the mnemonic for the symptoms?

Answer 3

BONES, MOANS, GROANS AND STONES.

· Bones - pain, osteoporosis.
· Moans - depression, fatigue.
· Groans - myalgia.
· Stones - kidney stones.

Question 4

Who is affected?

Answer 4

· Affects 1 in 500 women - highest among post-menopausal women.
· Affects 1 in 2000 men.
· Most common cause of hypercalcaemia in outpatients.
· Most commonly found in women aged between 50 and 60.

Question 5

What is the pathophysiology of a parathyroid adenoma?

Answer 5

Low serum calcium stimulates PTH secretion.

High calcium levels suppress PTH secretion.

In PHPT, PTH secretion is not suppressed by high calcium levels.

Excessive PTH leads to:
· Over-stimulation of bone resorption.
· Over-stimulation of the kidneys to reabsorb calcium and convert it to its active form. This active vitamin D is responsible for the GI absorption of calcium.

Question 6

What is the prognosis for a parathyroid adenoma?

Answer 6

Asymptomatic patients who don’t need surgery - 75% have stable disease for up to 10 years.
· 25% of these patients progress to needing surgery.
· 70% of young patients progress to needing surgery.

Most common cause of mortality is CVD - stroke, MI. Hypercalcaemic arrhythmias are rare.

Question 7

What is the aetiology of a parathyroid adenoma?

Answer 7

· PHPT is caused by inappropriate secretion of PTH, leading to hypercalcaemia.
· The most common cause is a parathyroid adenoma.
· Inherited disease is in 10-20%, leading to hyperfunctioning parathyroid glands - MEN1/2/4.
· Less than 1% are due to parathyroid malignancies.
· External neck irradiation.
· Lithium use.
· Associated with overexpression of cyclin D1 gene and MEN syndromes.

Question 8

What are the risk factors for parathyroid adenoma?

Answer 8

· Female.
· Aged 50-60 years.
· FHx of PHPT.
· Multiple Endocrine Neoplasia (MEN) 1, 2A or 4.
· Current or historical lithium treatment.
· Hx of head and neck irradiation.
· Cyclin D1 gene.

Question 9

What are the typical presenting signs and symptoms?

Answer 9

· Hx of osteoporosis or osteopenia. 
· Nephrolithiasis. 
· Bone pain.
· Poor sleep. 
· Fatigue, anxiety and depression. 
· Memory loss.
· Myalgias. 
· Paraesthesia and muscle cramps. 
· Constipation.

Question 10

Diagnosis requires what investigations?

Answer 10

· Serum calcium - high-normal to raised.
· Serum phosphate - decreased.
· PTH level - increased.
· Normal or raised urinary calcium in the presence of normal renal function.

Question 11

What other investigations might be done?

Answer 11

· 25-hydroxyvitamin D level - may be low.

· DXA scan.

Question 12

Differentials?

Answer 12

· Familial hypocalciuric hypercalcaemia. 
· Humoral hypercalcaemia of malignancy. 
· Multiple myeloma. 
· Thyrotoxicosis. 
· Leukaemia.
· Thiazide use.

Question 13

What are the treatment options for symptomatic OR asymptomatic patients with surgical indications?

Answer 13

· 1st line - Parathyroidectomy.
· Adjunct - Vitamin D supplementation.
· 2nd - Monitoring.
· Adjunct - Bisphosphonate.

Question 14

What are the treatment options for asymptomatic patients with no surgical indications?

Answer 14

· 1st line - Monitoring.
· Adjunct - Vitamin D supplementation.
· 2nd - Parathyroidectomy.

Question 15

What complications can occur?

Answer 15

· Osteoporosis. 
· Bone fractures.
· Nephrolithiasis. 
· Pneumothorax following surgery. 
· Hypocalcaemia following surgery. 
· Recurrent and superior laryngeal nerve injury following surgery.