Hyperparathyroidism

Question 1

Structure and Function of the Parathyroid Glands (3).

Answer 1

1. 4 Parathyroid Glands in 4 Corners of Thyroid Gland.
2. Chief Cells in the Glands.
3. PTH Release in Response to Hypocalcaemia.

Question 2

Functions of Parathyroid Hormone (4).

Answer 2

1. Increase Osteoclast Activity in Bones.
2. Increase Calcium Absorption from the Gut.
3. Increase Calcium Absorption from the Kidneys.
4. Increase Vitamin D Activity.

Question 3

Synergistic Activity of Vitamin D.

Answer 3

1. Increases Calcium Resorption from the Intestines.

2. PTH activates Vitamin D.

Question 4

What is Primary Hyperparathyroidism?

Answer 4

Uncontrolled PTH produced directly by a tumour of the parathyroid glands, leading to hypercalcaemia.

Question 5

Management of Primary Hyperparathyroidism.

Answer 5

Surgical Removal of the Tumour.

Question 6

Aetiology of Primary Hyperparathyroidism.

Answer 6

1. 80% - Solitary Adenoma.
2. 15% - Hyperplasia.
3. 4% - Multiple Adenoma.
4. 1% - Carcinoma.

Question 7

Clinical Presentation of Primary Hyperparathyroidism.

Answer 7

1. Elderly Female.
2. Unquenchable Thirst.
3. Inappropriately Normal/RaisedPTH.
4. Majority = Asymptomatic.
5. Hypercalcaemia.

Question 8

Associations of Primary Hyperparathyroidism (2).

Answer 8

1. Hypertension.

2. MEN I and II.

Question 9

Investigations of Primary Hyperparathyroidism (6).

Answer 9

1. Raised Calcium.
2. Low Phosphate.
3. Raised/Inappropriately Normal PTH.
4. X-Ray : Pepperpot Skull.
5. Technetium-MIBI Subtraction Scan.
6. Urine Calcium : Creatinine Clearance Ratio > 0.01.

Question 10

Management of Primary Hyperparathyroidism (3).

Answer 10

1. Definitive - Total Parathyroidectomy.
2. Conservative - No End Organ Damage AND Age > 50 AND Calcium < 0.25 mmol/L above the upper limit of normal.
3. If surgery is not suitable, Cinacalcet.

Question 11

Mechanism of Action of Cinacalcet.

Answer 11

Calcimimetic - ‘mimics’ action of Calcium on tissues by allosteric activation of a Calcium-sensing receptor.

Question 12

What is Secondary Hyperparathyroidism?

Answer 12

Insufficient Vitamin D or CKD leads to low absorption of Calcium from the intestines, kidneys and bones causing hypocalcaemia - hyperplasia of chief cells.

Question 13

Management of Secondary Hyperparathyroidism (2).

Answer 13

1. Correct Vitamin D Deficiency.

2. Perform a renal transplant to treat renal failure.

Question 14

Aetiology of Secondary Hyperparathyroidism.

Answer 14

1. Low Vitamin D.

2. CKD.

Question 15

Investigations of Secondary Hyperparathyroidism (4).

Answer 15

1. PTH Elevated.
2. Calcium Low/Normal.
3. Phosphate Elevated in CKD and Low in Vitamin D Deficiency.
4. Vitamin D Low.

Question 16

Indications for Surgery in Secondary Hyperparathyroidism (3).

Answer 16

1. Bone Pain.
2. Persistent Pruritus.
3. Soft Tissue Calcifications.

Question 17

What is Tertiary Hyperparathyroidism?

Answer 17

Secondary Hyperparathyroidism continues for a long period of time, leading to hyperplasia of the glands.

Question 18

Pathophysiology of Tertiary Hyperparathyroidism (4).

Answer 18

1. Baseline of PTH increases dramatically.
2. Even after cause is treated, PTH level remains inappropriately high.
3. High PTH in absence of previous pathology leads to high absorption of Calcium in the intestines, kidneys and bones.
4. Hypercalcaemia.

Question 19

Management of Tertiary Hyperparathyroidism.

Answer 19

Surgical Removal of Parathyroid Tissue.

Question 20

Aetiology of Tertiary Hyperparathyroidism.

Answer 20

Hyperplasia of all 4 Glands after Correction of Underlying Renal Disorder.

Question 21

Investigations of Tertiary Hyperparathyroidism.

Answer 21

1. Calcium - Normal/High.
2. PTH - High.
3. Phosphate - Low/Normal.
4. Vitamin D - Normal/Low.
5. ALP - Elevated.