Hyperparathyroidism

Question 1

Where are the parathyroid glands located

Answer 1

Four parathyroid glands situated posterior to the thyroid gland

Question 2

What hormone does the parathyroid glands produce?

Answer 2

Produce parathyroid hormone (PTH)

Question 3

What cells of the parathyroid gland produce parathyroid hormone (PTH)

Answer 3

The chief cells

Question 4

The chief cells of the parathyroid glands produce parathyroid hormone (PTH) in response to:

a) hypercalcaemia (high blood calcium)
b) hypocalcaemia (low blood calcium)

Answer 4

b) hypocalcaemia (low blood calcium)

Question 5

What are the 4 ways in which the parathyroid hormone (PTH) raises the blood calcium levels

Answer 5

Increasing osteoclast activity i.e. reabsorbing calcium from bones

Increase intestinal calcium absorption

Increase renal calcium absorption

Increase vitamin D activity by converting vitamin D to its active form

Question 6

What is the function of vitamin D

Answer 6

Vitamin D acts to increase calcium absorption from the intestines

Question 7

Define hyperparathyroidism

Answer 7

It is when there is excessive secretion of parathyroid hormone (PTH)

Question 8

Describe the biochemistry results of primary hyperparathyroidism

Answer 8

High PTH

High Serum Calcium

Question 9

Describe the biochemistry results of secondary hyperparathyroidism

Answer 9

High PTH

Normal/Low Serum Calcium

Question 10

Describe the biochemistry results of tertiary hyperparathyroidism

Answer 10

High PTH

High Serum Calcium

Question 11

Define primary hyperparathyroidism

Answer 11

Excess production of PTH by at least one parathyroid gland causing hypercalcaemia

Question 12

What is the most common cause of primary hyperthyroidism

Answer 12

Parathyroid adenoma

Question 13

Name three causes of primary hyperparathyroidism

Answer 13

Tumours e.g. parathyroid adenoma (most common)

Hyperplasia

Carcinoma (rare)

Question 14

Name the clinical features of primary hyperthyroidism

Answer 14

Asymptomatic or can cause hypercalcaemia

Question 15

What are the signs of hypercalcaemia

Answer 15

Mnemonic: Moans, Stones, Groans and Psychiatric Moans

• Painful Bones
• Renal Stones
• Abdominal Groans – due to GI symptoms e.g. nausea, vomiting, constipation, indigestion
• Psychiatric Moans – due to effects on nervous system e.g. fatigue, memory loss, psychosis, depression

Question 16

Name the two investigations for primary hyperparathyroidism

Answer 16

USS of the neck

Parathyroid MIBI scan (uses radiolabelled material to visualise the parathyroid glands)

Question 17

What is involved in the parathyroid MIBI scan

Answer 17

Involves the injection of radioactive material which is absorbed by hyperactive parathyroid glands. Images can be taken by a gamma camera

Question 18

What is the treatment for primary hyperparathyroidism

Answer 18

Surgical removal of the tumour or parathyroidectomy

Question 19

Define secondary hyperparathyroidism

Answer 19

Excess PTH production secondary to hypocalcaemia

Question 20

What are the two causes of secondary hyperparathyroidism

Answer 20

Vitamin D deficiency

Chronic kidney disease

Question 21

Describe the pathogenesis of secondary hyperparathyroidism

Answer 21

Vitamin D deficiency or chronic kidney disease causes low absorption of calcium from the intestines, kidneys and/or bones

The parathyroid glands reacts to the low serum calcium by excreting more parathyroid hormone

Overtime this leads to hyperplasia of the parathyroid glands.

Question 22

How is secondary hyperparathyroidism treated

Answer 22

Vitamin D replacement

OR

Renal transplant

Question 23

Define tertiary hyperparathyroidism

Answer 23

Autonomous PTH excess due to parathyroid hyperplasia in response to chronic secondary hyperparathyroidism

Question 24

Describe the pathogenesis of tertiary hyperparathyroidism

Answer 24

Chronic secondary hyperparathyroidism leads to hyperplasia of the parathyroid glands, which can increase in the baseline PTH level

When the cause of the secondary hyperparathyroidism is treated the parathyroid hormone level remains inappropriately high

This high level of parathyroid hormone in the absence of the previous pathology leads to high absorption of calcium in the intestines, kidneys and bones and causes hypercalcaemia.

Question 25

What is the cause of tertiary hyperparathyroidism

Answer 25

Prolonged secondary hyperparathyroidism

Question 26

What is the treatment for tertiary hyperparathyroidism

Answer 26

Pharmaceutical

Cinacalcet – mimics the action of calcium on tissues

Surgically

Total or subtotal parathyroidectomy (removal of part or all of the parathyroid tissue returning the parathyroid hormone to an appropriate level)

Risk of hypoparathyroidism requiring calcium supplementation