8 - Pathology of the Parathyroid

Question 1

What are the parathyroid pathologies that we will cover?

Answer 1

• Hyperparathyroidism (primary and secondary)
• Parathyroid cancer
• Hypoparathyroidism

Question 2

What is the most common cause of primary hyperparathyroidism?

Answer 2

KNOW THIS

A parathyroid gland adenoma, which is a benign tumor of the parathyroid gland

This leads to an autonomous overproduction of PTH

Question 3

What happens when there is excess parathyroid hormone?

Answer 3

Hypercalcemia

Question 4

What does excess calcium in the urine cause?

Answer 4

Flank pain and hematuria

Flank pain refers to pain or discomfort in your upper abdomen or back

Question 5

What are the four signature features of primary hyperparathyroidism?

Answer 5

“Stones and Bones”

“Groans and Moans”

Question 6

Describe the stones and bones

Answer 6

• Kindey stones, which are the most common presentation

- Bone changes (bone lesions - painful)

Question 7

Describe the groans and moans

Answer 7

• Groans, which are due to stomach pain… High calcium stimulates gastrin and acid secretion leading to peptic ulcers
• Moans are from depression or psychosis and fatigue - due to hypercalcemia

Question 8

How do you remember the clinical presentation of hyperparathyroidism?

Answer 8

Renal stones
Painful bones
Abdominal groans
Mental moans

Question 9

What can be problematic when looking for a parthyroid adenoma?

Answer 9

Remember parathyroid adenomas are the most common cause of hyperparathyroidism

10% of parathyroid glands (each person has 4 of them) are located ectopically

Need radigraphically guided scan

Question 10

What is the second most common cause of hyperparathyroidism?

Answer 10

Parathyroid hyperplasia

Question 11

What would you look for if you though there was parathyroid hyperplasia?

Answer 11

ALL FOUR parathyroid glands would be enlarged (not just one like if there was a tumor on one of them)

Question 12

What patients would you be suspicous of parathyroid hyperplasia in?

Answer 12

Patients with MEN

M = multiple
E = endocrine
N = neoplasia

Question 13

What is the difference between an adenoma and hyperplasia when diagnosed histologically?

Answer 13

Adenoma
- There is a rim of normal parathyroid tissue
- Can see the hyperproliferated part and the compressed normal part
And you can see a capsule there

Hyperplasia
- There is NOT a rim of normal parathyroid tissue

Question 14

What is the MOST COMMON cause of secondary hyperparathyroidism?

Answer 14

EMPHASIZED THIS
- Chronic renal failure

In any exam, you get a clinical situation were there is chronic renal failure and then they tell you that the calcium is low, you need to think about secondary hyperparathyroidism

KNOW THIS

Remember, ALL FOUR glands would be enlarged in this case

Question 15

What lab values would you see with secondary hyperparathyroidism due to chronic renal failure?

Answer 15

• Low calcium
• High parathyroid hormone

The calcium is low because of the chroic renal failure (not reabsorbing calcium)

This causes the parathyroid gland to go into overdrive in order to try to increase calcium

The “overdrive” causes parathyroid hyperplasia, but the parathyroid can’t keep up with the amount of calcium lost in the urine

Question 16

What is a major concern in patients with secondary hyperparathyroidism?

Answer 16

Bone disease

- renal osteodystrophy leading to brown tumors

Question 17

What histological finding would make you think parathyroid carcinoma?

Answer 17

EMPHASIZED THIS

• Thick fibrous bands
• 90% of histological images of parathyroid carcinomas will have this

Question 18

What is hypoparathyroidism?

Answer 18

Lack of parathyroid

• Most common cause is autoimmune
• Can also happen accidentally when a surgeon is removing the thyroid or a lymph node
• Less common is DiGeorge syndrome

Question 19

What are the symptoms of hypoparathyroidism?

Answer 19

Symptoms of hypocalcemia

• mental changes
• circumoral paresthesia
• Chvostek sign
• Trousseau sign

Progresses to convusions and tetany