Hyperparathyroidism

Question 1

Which cells produce PTH

Answer 1

Chief cells in the glands, produce parathyroid hormone in response to hypocalcaemia (low blood calcium).

Question 2

How does PTH raise blood calcium

Answer 2

Increasing osteoclast activity in bones (reabsorbing calcium from bones)

Increasing calcium absorption from the gut

Increasing calcium absorption from the kidneys

Increasing vitamin D activity

Question 3

How does vitamin D increase blood calcium levels

Answer 3

Acts to increase calcium absorption from the intestines.

Parathyroid hormone acts on vitamin D to convert it into active forms. So vitamin D and parathyroid hormone act together to raise blood calcium levels.

Question 4

Symptoms of hypercalcaemia

Answer 4

Renal stones
Painful bones
Abdominal groans refers to symptoms of constipation, nausea and vomiting

Psychiatric moans refers to symptoms of fatigue, depression and psychosis

Question 5

What is primary hyperparathyroidism caused by

Answer 5

Uncontrolled parathyroid hormone produced directly by a tumour of the parathyroid glands.

This leads to hypercalcaemia

Question 6

How is primary hyperparathyroidism treated

Answer 6

Surgical removal of tumour

Question 7

What is secondary hyperparathyroidism

Answer 7

Where insufficient vitamin D or chronic renal failure leads to low absorption of calcium from the intestines, kidneys and bones.

This causes hypocalcaemia

Question 8

Why is there raised PTH in secondary hyperparathyroidism

Answer 8

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

Over time the total number of cells in the parathyroid glands increase as they respond to the increased need to produce parathyroid hormone.

This is called hyperplasia. The glands become more bulky. The serum calcium level will be low or normal but the parathyroid hormone will be high.

Question 9

How is secondary parathyroidism treated

Answer 9

Correcting the vitamin D deficiency or performing a renal transplant to treat renal failure.

Question 10

What causes tertiary hyperparathyroidism

Answer 10

This happens when secondary hyperparathyroidism continues for a long period of time.

It leads to hyperplasia of the glands. The baseline level of parathyroid hormone increases dramatically.

Then 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 11

How is tertiary hyperparathyroidism treated

Answer 11

Surgically removing part of the parathyroid tissue to return the parathyroid hormone to an appropriate level.

Question 12

Pathophys of paget’s disease of bone

Answer 12

There is excessive bone turnover due to excessive activity of both osteoblasts and osteoclasts leading to sclerosis and lysis

Question 13

Presentation of paget’s disease

Answer 13

Bone pain
Bone deformity
Fractures
Hearing loss can occur if it affects the bones of the ear

Question 14

X-ray findings in paget’s disease of the bone

Answer 14

Bone enlargement and deformity
Osteoporosis circumscripta
Cotton wool appearance of skull
V-shaped defects

Question 15

What is osteoporosis circumscripta

Answer 15

Describes well defined osteolytic lesions that appear less dense compared with normal bone

Question 16

What does cotton wool appearance of skull in paget’s disease refer to

Answer 16

describes poorly defined patchy areas of increased density (sclerosis) and decreased density (lysis)

Question 17

What are V-shaped defects in Paget’s disease of the bone

Answer 17

“V-shaped defects” in the long bones are V shaped osteolytic bone lesions within the healthy bone

Question 18

Biochem findings in Paget’s disease of the bone

Answer 18

Raised alkaline phosphatase (and other LFTs are normal)
Normal calcium
Normal phosphate

Question 19

Predisposing factors for Paget’s disease of the bone

Answer 19

increasing age
male sex
northern latitude
family history

Question 20

Management of Paget’s disease of the bone

Answer 20

Bisphosphonates
NSAIDs for bone pain
Calcium and vitamin D supplements
Surgery rarely

Question 21

Complications of Paget’s disease of the bone

Answer 21

deafness (cranial nerve entrapment)
osteosarcoma 
fractures
skull thickening
high-output cardiac failure
Spinal stenosis

Question 22

Initial management of hypercalcaemia

Answer 22

IV fluid therapy(3-4l/day)

Following rehydration bisphosphonates may be used

Question 23

Other options for management of hypercalcaemia

Answer 23

calcitonin - quicker effect than bisphosphonates

steroids in sarcoidosis

Question 24

What is osteomalacia

Answer 24

Osteomalacia is a condition where there is defective bone mineralisation causing “soft” bones

This results from insufficient vitamin D

Question 25

What are looser zones

Answer 25

Fragility fractures that go partially through the bone

Question 26

Risk factors for osteomalacia

Answer 26

Darker skin
Low exposure to sunlight
Colder climates
Time indoors

Question 27

Interpretation of serum 25-hydroxyvitamin D levels

Answer 27

<25 nmol/L – vitamin D deficiency

25 – 50 nmol/L – vitamin D insufficiency

75 nmol/L or above is optimal

Question 28

Treatment of osteomalacia

Answer 28

Treatment is with supplementary vitamin D