Diseases Of The Parathyroid Glands (both pathology and Crutchfield lectures)

Question 1

What are the two cells found in parathyroid glands

Answer 1

1) chief principle cells
- stains basophilic
- actually secrete PTH
- **exhibits negative feedback by increased free calcium in blood

2) oxyphil cells
- stain acidophilc and contains large amounts of mitochondria

Question 2

Hyperparathyroidism

Answer 2

Primary

• autonomous overproduction of PTH
• most common cause of hypercalcemia
• is caused by: adenoma (90%), primary hyperplasia (9%) and parathyroid carcinoma (1%)
• 75-85% of tumors ar solitary

Secondary

Question 3

What are the two gene abnormaltes associated with parathyroid tumors

Answer 3

Cyclin D1 gene rearrangements

• usually a inversion on chromosome 11 which moves cyclin D1 next to PTH (cyclin D1 is a positive regulator so it will excessively promote PTH gene transcription)
• 10-20% adenomas have this

MEN1 mutations
- 10-30% of Adenomas have this

Question 4

Difference between parathyroid hyperplasia and parathyroid adenomas

Answer 4

Adenomas = solitary nodules
- usually small tan lesions that are well defined and weigh less than 5g

Parathyroid hyperplasia = diffuse or multi nodular pattern usually
- usually grey-white neoplasms that weigh near 10g

both show primary Chief cells on histology and near no oxyphil cells

Question 5

What can bones seen in chronic hyperparathyroidism sometimes look like on gross examination

Answer 5

“Brown tumors of bone”

- caused by aggregations or osteoclasts, reactive giant cells and hemorrhagic debris

Question 6

Clincial features of primary hyperparathyroidism

Answer 6

More common women (4:1) and more common in adults

Most common manifestation is increased serum calcium and if it becomes symptomatic most common is polyuria with kidney stones

Question 7

What is the msot common cause of symptomatic pseudo hyperparathyroidism?

Answer 7

Hypercalcemia of malignancy

- results in apparent hyperparathyroidism but there will be Low PTH since PTHrP is mimicking it

Question 8

Differences in lab values between hyperparathyroidism caused by parathyroid hyperfunction and caused by nonparathyroid diseases

Answer 8

Caused by parathyroid hyper-function

• excess PTH
• hypophosphatemia
• high levels of both calcium and phosphate in ruin

Caused by non-parathyroid diseases

• low PTH
• hyperphosphatemia
• high levels of calcium in urine but low phosphate

Question 9

What symptoms are common in primary hyperparathyroidism

Answer 9

Painful bones

Renal stones

Abdominal pains

Polyuria/polydipsia

Corneal calcification

Lethargy

Question 10

What is the most common cause of secondary hyperparathyroidism

Answer 10

Chronic renal failure

Also almost always shows hyperplasia in parathyroid glands

Question 11

What is a commonly feared consequence of hyperphosphatemia

Answer 11

Calciphylaxis

- causes metastatic calcification of blood vessels which leads to serious ischemic damage

Question 12

What are the most common causes of hypoparathryodism?

Answer 12

Surgical ablation

Congenital absence in Thymic aplasia
- seen is Di-George syndrome (22q11)

Autoimmune hypoparathryodism

Question 13

Hypoparathryodism clinical manifestations

Answer 13

Are secondary to hypocalcemia

• neuropathic damage (tingling, muscle spasms, fascial spasms and tetanus)
• cardiac arrhythmias
• increased intracranial pressure and seizures

Chronic = cataracts and dental abnormalties

Question 14

What is the most common tumor of hyperparathyroidism?

Answer 14

Solitary benign adenoma in a parathyroid gland

Question 15

Who first discovered parathyroid glands?

Answer 15

Ivan sandstrom

Question 16

Who is rosalyn halos?

Answer 16

Won the Nobel prize for coming up with the radioimmunoassay for insulin and PTH

Question 17

What is the blood supply to the parathyroid glands?

Answer 17

Inferior thyroid artery

- a branch of the thryocervical trunk

Question 18

What are patient symptoms and lab values that are suggestive of parathyroid disorders

Answer 18

Features

• ab pain
• coughing/dyspnea
• headache
• seizures
• bone pain
• calcium stones
• pancreatitis
• anger/depression that is unexplained (psychic overtones)
• palpitation and arrhythmias
• masses, nausea/vomiting

Lab values

• high serum calcium
• high PTH
• low phosphate in blood

Hypocalcemia = Chevstek (tap facial nerve and cause tetany), trousseau sign (carpal pedal spasm When you blow up a leg cuff 20 mg over their arterial pressure for 2-3 seconds)

Question 19

What are the most common sites for normal parathyroid glands

Answer 19

60% = paraesophageal
- usually in the esophageal groove and posterior to the thyroid gland

25% = thymus

10% = intrathryoidal

4% = carotid sheath

1% = everywhere else

Question 20

How do you calculate the correct patient calcium level from a BMP

Answer 20

Using the following formula:

(Normal albumin (4.0) - current albumin measured times 0.8)
- take this value and add it to the measured calcium level in the BMP

this gives you a corrected calcemia level based on hypo or hyper albuminemia levels

Question 21

What is the importance of the carotid body and artery in thyroid gland/parathyroid gland operations

Answer 21

If you bump or misplace the carotid body/sinus = bradycardia and hypotension

• can give lidocaine to prevent this**
• this derived from neural crest cells and is VERY sensitive

sometimes parathyroid gland tumors can get inside the carotid sheath

Question 22

Review of what are the common causes of Virchow node?

Answer 22

Women = breast or lung

Men = lung

both also are possible to be GI malignancy

Question 23

What is the best scans to use to look at parathyroid glands?

Answer 23

DONT use MRI/CT or Xrays (none of these really can view the parathyroid glands properly)
- it still can be but is so unusual that it is not first line for diagnosing

Instead use a physical exam, lab levels and EV scanning

• Use a sestamibi scan uses radioactive technetium-99 (same cardiac nuclear medicine scan so will also light up the heart). This is good for primary parathyroid hyperplasia or adenomas .
• sestamibii scans often can be misread**

Question 24

Use of 11 C-choline and 18 Flurorocholine complexes in PET/CT scans for parathyroid

Answer 24

This is another way to find parathyroid adenomas using CT cross section

Question 25

What MEN syndrome is most heavily tied to parathyroid hyperplasia

Answer 25

MEN1

- also very common shows zollinger Ellison syndrome with gastrinomas