Disorders of Parathyroid glands

Question 2

from where is the parathyroid derived?

Answer 2

from the third and fourth branchial pouches.

Question 3

how many parathyroid glands are there?

what cells compose the parathyroid gland?

Answer 3

4

oxyphil and chief cells

Question 4

what do chief cells synthesize?

Answer 4

PTH

Question 5

what are the functions of PTH?

Answer 5

1. Activates osteoclasts (mobilizes Ca from bone)
2. Increases resorption of calcium from renal tubules.
3. Increases the conversion of vitamin D to its active form.

• Increases Ca absorption from GIT.
  1. Increases urinary phosphate excretion.

Question 6

how does PTH maintain ionized calcium levels in blood?

Answer 6

• Increases bone resorption and
• Renal and GIT resorption of calcium

Question 7

PTH secretion is controlled by what?

Answer 7

Level of free ionized calcium in blood stream

• PTH secretion stimulated by hypocalcemia
• PTH secretion suppressed by hypercalcemia

Question 8

what does Total Serum calcium represent?

Answer 8

bound calcium + free calcium

Question 9

what is the activated form of calcium?

Answer 9

free calcium

Question 10

What are the effect of hypoalbuminemia on calcium levels?

Answer 10

• Causes decreased total serum calcium
  
  • Due to a decrease in Ca bound to albumin.
• Normal free Ca levels, normal PTH
• No evidence of tetany**.

Question 11

what is the effect of respiratory or metabolic alkalosis on calcium levels?

Answer 11

• Alkalosis increases negative charges on albumin.
• Extra negative charges bind some of the free Ca
• Total serum calcium remains normal
• Decreased free calcium, increased PTH
• Patient develops tetany**

Question 12

who secretes Calcitonin?

what stimulates the synthesis of calcitonin?

Answer 12

C cells of thyroid

hypercalcemia

Question 13

what are the actions of calcitonin?

Answer 13

• Inhibits bone resorption by inhibiting the activity of osteoclasts.
• Inhibits absorption of calcium from intestine.
• Net effect = decreased calcium levels

Question 14

what are the 2 Disorders of Parathyroid glands?

Answer 14

1. Hyperparathyroidism
2. Hypoparathyroidism

Question 15

Hyperparathyroidism (HPTH) can divide into 2 types?

Answer 15

1. Primary Hyperparathyroidism
2. Secondary Hyperparathyroidism

Question 16

Primary hyperparathyroidism is characterized by what?

usually affects who?

Answer 16

Unregulated overproduction* of PTH by the parathyroid leading to hypercalcemia.

50 y/o women

Question 17

what are the 2 types of primary hyperparathyroidism?

Answer 17

sporadic

associated with MEN I or II

Question 18

what is a Parathyroid adenoma’s gross findings?

which parathyroid gland is usually affected

Answer 18

A benign tumor, Solitary & well circumscribed.

Right inferior parathyroid gland is most often involved

Question 19

what are the parthyroid glands micro findings?

Answer 19

• Composed of sheets of chief cells with no intervening fat.
• Remainder of the gland plus all other glands show atrophy.
• due to suppression of PTH by hypercalcemia.

Question 20

what is this test called?

what is it showing?

Answer 20

parathyroid Tc99 scan

parathyroid adenoma

Question 22

how many glands are affected by primary parathyroid hyperplasia?

what are the micro findings?

Answer 22

all 4 glands

chief cell hyperplasia with sparse fat tissue.

Question 23

what is this showing?

Answer 23

parathyroid hyperplasia

Question 25

most cases of hyperparathyroidism are?

Answer 25

asymptomatic and found incidentally

Question 26

what are the Primary Hyperparathyroidism Renal Clinical findings?

Answer 26

• Calcium oxalate stones = nephrolithiasis (most common presentation**)
• Nephrocalcinosis (causes polyuria and renal failure).

Question 27

what are the Primary Hyperparathyroidism GIT Clinical findings?

Answer 27

* Peptic ulcer disease: calcium stimulates gastrin release which increases gastric acid. * Acute pancreatitis: calcium activates phospholipases * Constipation: Most common\*\* GI complaint (hypomotility)

Question 28

what are the Primary Hyperparathyroidism Bones Clinical findings? what will you see in micro findings?

Answer 28

Osteitis Fibrosa Cystica * Cystic and hemorrhagic bone lesion * Caused by increased osteoclastic activity * Commonly involves the jaw and fingers Aggregates of osteoclasts, reactive giant cells and hemorrhage mimicking neoplasm. Called the "brown tumor" of hyperparathyroidism

Question 29

What are the Primary Hyperparathyroidism Eye Clinical findings?

Answer 29

* Band keratopathy in the limbus of the eye * Due to Metastatic calcifications

Question 30

What are the Primary Hyperparathyroidism CVS Clinical findings?

Answer 30

* Diastolic hypertension * calcium increases muscular contraction in the peripheral resistance vessels.

Question 31

What are the Primary Hyperparathyroidism CNS Clinical findings?

Answer 31

Depression and seizures (Metastatic calcification)

Question 32

what are the Laboratory findings found in Primary HyperParaThyroidism?

Answer 32

* Increased serum PTH * Increased serum calcium = hypercalcemia * Decreased serum phosphate = hypophosphatemia

Question 33

what is this showing?

Answer 33

parathyroid hyperplasia

Question 35

what are the Primary Hyperparathyroidism GIT Clinical findings?

Answer 35

* Peptic ulcer disease: calcium stimulates gastrin release which increases gastric acid. * Acute pancreatitis: calcium activates phospholipases * Constipation: Most common\*\* GI complaint (hypomotility)

Question 37

how does Malignancy induced hypercalcemia happen?

Answer 37

* Bone metastasis with activation of osteoclasts * Ectopic secretion of PTH related protein (SCC of lung, RCC) * Multiple myeloma: ↑ secretion of osteoclast activating factor (IL-1) by plasma cells.

Question 38

how does Sarcoidosis happen?

Answer 38

Macrophages in granuloma synthesize 1 alpha hydroxylase, causing Hypervitaminosis D

Question 39

what is the most common cause of secondary hyperparathyroidism?

Answer 39

chronic renal failure

Question 40

what do you see in the labs for 2ry hyperparathyroidism?

Answer 40

Decreased calcium, increased PTH, increased phosphate.

Question 41

what is Primary hypoparathyroidism?

Answer 41

Refers to hypofunction of parathyroid gland leading to hypocalcemia.

Question 42

what is the etiology of 1ry **hypo**parathyroidsm?

Answer 42

* Previous thyroid surgery (most common cause) * Di George syndrome: congenital absence of parathyroid glands * Autoimmune hypoparathyroidism * Hypomagnesemia: required for PTH activation

Question 43

PTHrP is always made by ?

Answer 43

the tumor, not the body

Question 44

Reduction in total and ionized calcium levels in 1ry hypoparathyroidism results in what?

Answer 44

* Tetany * Calcification of basal ganglia * Due to metastatic calcification * Increased phosphorus drives Ca into brain * Cataracts * Candida infection (?cause) * Prolonged QT interval

Question 45

why does tetany happen in 1ry hypoparathyroidism?

Answer 45

due to decreased ionized calcium. * Decreased ionized Ca causes partial depolarization of nerve and muscle A smaller stimulus is required to initiate an action potential.

Question 46

what 2 signs can you find in 1ry hypoparathyroidism?

Answer 46

1. Carpopedal spasm: thumb flexes into palm 2. Chovestek’s sign: facial twitch after tapping the facial nerve.

Question 47

what Laboratory findings are indicative of 1ry hypoparathyroidism?

Answer 47

1. Low PTH 2. Hypocalcemia 3. Hyperphosphatemia

Question 48

what is Pseudohypoparathyroidism?

Answer 48

Sex linked inherited disease. Characterized by end organ resistance (kidney) to PTH.

Question 49

what do patients with pseudohypoparathyroidism have?

Answer 49

* Mental retardation * Calcification of basal ganglia * Short 4th and 5th metacarpals\*\* (knuckle-knuckle- dimple – dimple sign) * Short stature and other skeletal abnormalities.

Question 50

what are the lab findings in pseudohypoparathyroidism?

Answer 50

Hypocalcemia, hyperphosphatemia and normal or high PTH.

Question 51

what are 4 other causes of hypocalcemia?

Answer 51

1. Acute pancreatitis: Calcium bound to fatty acids in enzymatic fat necrosis. 2. Hypovitaminosis D: Chronic renal failure: MCC 3. Hypoalbuminemia: MCC of hypocalcemia 4. Hypomagnesemia

Question 52

fill the blanks

Answer 52