PathCAL

Question 1

What is primary hyperparathyroidism?

Answer 1

Hyperparathyroidism due to some abnormality in the parathyroids

Question 2

What is secondary hyperparathyroidism?

Answer 2

hyperparathyroidism occurs because the parathyroids are reacting to an abnormality of calcium metabolism due to something outside the parathyroids
occurs in patients with low serum calcium, particularly in long-standing renal disease, parathyroids are stimulated to produce more parathyroid hormone.

Question 3

In a patient with primary hyperparathyroidism, what would be the usual abnormality in the parathyroids that we should look for?

Answer 3

It would be a tumour (neoplasm), particularly a benign tumour: an adenoma.
Hyperplasia would be the other possibility, but primary hyperplasia of the parathyroids is pretty rare.
A malignant neoplasm of the parathyroid would be very rare indeed.
The adenoma churns out excessive amounts of parathyroid hormone.
But, like other benign neoplasms, it’s autonomous and doesn’t respond to the body’s normal growth control mechanisms. Normally, of course, the parathyroid would only secrete increased amounts of parathyroid hormone in response to a fall in the plasma calcium level.

Question 4

What are recognised findings in primary hyperparathyroidism?

Answer 4

• Raised plasma calcium levels (osteoclasts resorb bone)
• Thickened osteoid seams on bony trabeculae (as a result of the increased osteoblastic activity, the osteoid seams become a bit thicker)
• Metastatic calcification (deposition of calcium in normal tissues)
• Increased osteoblastic activity (compensate for the resorbed bone, although the overall net result is loss of bone)

Question 5

What basic pathological change do we expect parathyroids to show in secondary hyperparathyroidism?

Answer 5

cells divide and the number of cells increases. So it’s hyperplasia, not hypertrophy.
Usually there is, in point of fact, hyperplasia of all four parathyroids, as they’d all tend to react together, as a team, so to speak

Question 6

What name is applied to the changes seen in the bones in people with long-standing kidney disease?

Answer 6

Renal osteodystrophy

Question 7

Explain what happens to the bone and its control in a patient with chronic renal disease

Answer 7

The kidney normally adds a second -OH group to hydroxycalciferol (hydroxy-vitamin D). This becomes reduced if the renal parenchyma stops working in chronic disease. So there is effective vitamin D deficiency: low plasma calcium, increased resorption of calcium from bone, osteoid seams on bony trabeculae, bone signs on X-ray.
The parathyroids react to reduced plasma calcium by becoming hyperplastic: they secrete parathyroid hormone. This promotes osteoclastic activity and calcium is resorbed from bone, restoring the plasma level, but damaging the bone.
The bone disease in people with chronic renal disease is thus a combination of osteomalacia and secondary hyperparathyroidism.

Question 8

What is expected in people with renal osteodystrophy?

Answer 8

• Increased osteoid (increased osteoid seams due to osteomalacia because kidneys are too damaged to hydroxylate enough Vit D)
• Raised parathyroid hormone levels in blood
• Reduced plasma calcium levels (lack of 1,25-dihydroxy-D3)
• Increased osteoclastic activity (stimulated by parathyroid hormone)

Question 9

How do we treat primary hyperparathyroidism?

Answer 9

surgeon to operate and explore the patient’s neck. Usually there will be one (sometimes two) adenoma, which can be removed. This cures the patient.

Question 10

How do we treat secondary hyperparathyroidism?

Answer 10

likely to find that all the parathyroids are enlarged, due to hyperplasia. They must all be removed. Obviously this would leave the patient with no parathyroid tissue and it’s now practice to transplant a small amount of parathyroid tissue to the skin of the forearm, where it may be explored subsequently if the hypercalcaemia recurs.

Question 11

Describe Paget’s Disease

Answer 11

markedly increased resorption of bone and deposition of large amounts of woven bone
Mosaic of woven bone, trabeculae in different directions

Question 12

What substance in the blood is measured to indicate osteoblastic activity?

Answer 12

Increased levels of alkaline phosphatase in the blood is a sign of increased osteoblastic activity, with increased deposition of bone.
In Paget’s disease the level of alkaline phosphatase in the blood can be increased considerably.

Question 13

What is it called when Paget’s disease affects just one bone?

Answer 13

Monostotic Paget’s Disease

Question 14

What are the recognised consequences of excessive bone deposition in Paget’s Disease?

Answer 14

• Deafness (ostia of cranial nerves blocked by bone deposition)
• Nerve compression
• Fractures (weakened bone)
• Bone pain
• Malignancy

Question 15

What could cause Paget’s disease?

Answer 15

It seems that the basic abnormality in this disease is in the osteoclasts.
Infection with a slow virus was suggested some years ago, but nobody has come up with good evidence of this.

Question 16

What is the drug treatment for Paget’s Disease?

Answer 16

Bisphosphonates. Note the -s- as the third letter near the beginning, by the way! The bisphosphonates are taken up by the osteoclasts and kill them off.
Bisphosphonates are now the treatment of choice in Paget’s disease of bone.
Biphosphonates constitute a group of drugs, one being alendronate.

Question 17

What are the main bone changes in Paget’s Disease?

Answer 17

Increased osteoclastic and osteoblastic activity.
Thick bone seams.
Mosaic pattern, due to deposition of bone in different directions.
Bending of bone, due to weakness.