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(OMS2) ENRP Exam 2 > Parathyroid pathalogy > Flashcards

Parathyroid pathalogy Flashcards

1
Q

What are the 3 predominant cell types of the parathyroid glands

A

◦ Chief cells
◦ Oxyphil cells
◦ Adipocytes

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2
Q

Principle function of the parathyroid gland

A

calcium homeostasis

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3
Q

How does PTH work

A

◦ Directly releases calcium from bone

◦ Exerts effects on the kidney
◦ Calcium resorption
◦ blocks Phosphate resorption

◦ Conversion of 25(OH)D to 1,25(OH)2D in the
kidney
◦ Further mobilizes calcium from bone and
intestine

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4
Q

What regulates the amount of PTH secreted from the parathyroid glands?

A

The Calcium-sensing receptor (CaSR)

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5
Q

What is the most common cause of primary hyperparathyroidism

A

Adenoma

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6
Q

Symptoms of primary hyperparathyroidism

A
  1. Painful bones
    • osteoporosis/osteitis fibrosis cystica
  2. Renal stones
    • nephrolithiasis
  3. Abdominal groans
    • constipation, gallstones
  4. Psychic moans
    • depression, lethargy, seizures
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7
Q

How does Osteitis Fibrosis Cystica (von Recklinghausen’s disease of bone) start

A

Starts as a brown tumor

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8
Q

Describe Osteitis Fibrosis Cystica

A
  1. osteoclast driven bone destruction
  2. small fractures
  3. hemorrhage and reactive tissue
  4. cystic brown tumors
  5. can look like metastatic disease!
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9
Q

How is hyperparathyroidism found in real life

A

Often asymptomatic.

High calcium incidentally found on routine lab work

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10
Q

Describe a parathyroid adenoma

A

Benign neoplasm of parathyroid chief or oxyphil cells

typically solitary

can be surrounded by a rim of normal parathyroid tissue

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11
Q

What gene mutation is associated with parathyroid adenomas?

A

MEN1

sporadic somatic MEN1 mutations are common

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12
Q

Is primary or secondary parathyroid hyperplasia more common?

A

secondary by far

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13
Q

How does one distinguish between an adenoma and primary hyperplasia

A

one gland is affected with adenoma

all glands are affected with hyperplasia

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14
Q

Does parathyroid hyperplasia have a normal rim of parathyroid tissue on histology?

A

no

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15
Q

What is the most telltale sign of parathyroid carcinoma?

A

Metastasis

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16
Q

What are highly suggestive features of parathyroid carcinoma

A
  1. Invasion of adjacent tissues
  2. Vascular invasion
  3. Elevated PTH that doesn’t go down after surgery
17
Q

How does hypercalcemia from hyperparathyroidism present?

From non-parathyroid sources?

A
  1. Most likely to be asymptomatic or have
    subtle symptoms
    ◦ Most commonly due to parathyroid
    adenoma
  2. More likely to be overt/symptomatic
    (mental status changes, nausea/vomiting,
    EKG changes – shortened QT interval)
18
Q

Most common cause of symptomatic hypercalcemia

A

malignancy

19
Q

What are the 2 mechanisms of hypercalcemia in malignancy

A
  1. Humoral hypercalcemia of malignancy (HHM)

2. Local osteolytic hypercalcemia

20
Q

Describe Humoral hypercalcemia of malignancy

HHM

A

PTHrP (80%)
◦ Analogous to PTH
◦ Squamous carcinomas (and many others)

Vitamin D-mediated
◦ Lymphomas

21
Q

Describe local osteolytic hypercalcemia

A

Release of calcium - osteoclastic bone resorption
◦ Breast Carcinoma
◦ Myeloma

22
Q

What is the diagnosis when PTH is high but calcium is low?

A

secondary parathyroid hyperplasia

23
Q

What is the typical endpoint of secondary parathyroid hyperplasia?

A

4 gland hyperplasia

24
Q

What is renal osteodystrophy

A

Dissecting osteitis in hyperparathyroidism

25
Q

What can renal osteodystrophy lead to in secondary hyperparathyroidism?

A

Rugger Jersey Sign on vertebral xray

26
Q

Describe calciphylaxis

A

Extensive calcification and occlusion of blood vessels with resultant ischemia as a result of Secondary hyperparathyroidism

27
Q

What do calciphylaxis patients die from?

A

sepsis/gangrene

28
Q

What is the cause of tertiary hyperparathyroidism

A

prolonged hypocalcemia –> autonomous function of the parathyroid glands

29
Q

Clinical features of hypocalcemia

A

◦ Behavioral disturbance/stupor
◦ Numbness and parasthesias
◦ Muscle cramps, spasms (tetany)
◦ Convulsions

30
Q

Physical exam finding of hypocalcemia

A

◦ Trosseau sign positive
◦ Chvostek sign positive
◦ Prolonged QT interval on ECG

31
Q

Describe Chromosome 22q11.2 Deletion Syndrome:

DiGeorge syndrome

A 
Facial nomalies
cyanosis
infection
tetany
ToF
truncus arteriosus
thymic hypo/aplasia
hypocalcemia
32
Q

Describe an inactivating CaSR mutation

A

Thinks there isn’t enough calcium even when there is

Turns on PTH
◦ Hypercalcemia

Reduces renal excretion
◦ Hypocalciuria

Familial hypocalciuric
hypercalcemia

33
Q

Describe an activating CaSR mutation

A

Thinks there is plenty of calcium even when there isn’t

Turns off PTH
◦ Hypocalcemia

Increases renal excretion
◦ Hypercalciuria

Autosomal dominant hypoPTH
(hypercalciuric hypocalcemia)

34
Q

What is pseudohypoparathyroidism

A

hypocalcemia despite a high serum PTH

35
Q

Why does pseudohypoparathyroidism do what it do?

A

Resistance to PTH!
◦ Related to G-protein receptor pathways
◦ Can affect other hormone pathways: TSH, LH/FSH

36
Q

Describe Albright’s hereditary osteodystrophy

A
  1. Short stature and obesity
  2. Shortened phalanges of upper extremity
  3. Shortened phalanges of lower extremity

Other findings include dental abnormalities, subcutaneous
ossification, cataracts
Occasionally, seizures and tetany

37
Q

What is a frequent mutation in Pseudohypoparathyroidism

A

GNAS

(OMS2) ENRP Exam 2 (9 decks)

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