EXAM #1: PARATHYROID DISEASES

Question 1

What is the embryologic origin of the parathyroid glands?

Answer 1

Superior= 4th pouch
Inferior= 3rd pouch

Question 2

What is a common location of ectopic parathyroid gland?

Answer 2

Superior mediastinum

Question 3

What are the two major types of cells in the parathyroid gland?

Answer 3

1) Chief cells

2) Oxyphil cells

Question 4

What chromosome is the gene that is responsible for PTH located on?

Answer 4

Chromosome 11

Question 5

How should you order PTH levels?

Answer 5

iPTH–intact PTH

*Note that the breakdown products also have biologic activity

Question 6

What controls PTH secretion?

Answer 6

Ca++

• Mg++
• Vitamin D
• Catecholamines

*Low Ca++ leads to PTH secretion

Question 7

What are the three target organs for PTH?

Answer 7

1) Bone
2) Intestinal mucosa
3) Kidney

Question 8

What is the effect of PTH on bone?

Answer 8

Increased osteoclast activity causing resorption (release into circulation) of Ca++ and phosphate

Question 9

What is the effect of PTH on the kidney?

Answer 9

• Retain Ca++

- Excretion of phosphate

Question 10

What is the effect of PTH on the gut?

Answer 10

Increased gut absorption of Ca++

Question 11

What is the NET effect of elevated PTH?

Answer 11

1) Increased serum Ca++

2) Decreased serum phosphate

Question 12

Where does Ca++ absorption occur in the kidney?

Answer 12

Proximal tubule

Question 13

Where does PTH fine-tune Ca++ in the kidney?

Answer 13

DISTAL nephron

Question 14

What is the effect of PTH on bicarbonate?

Answer 14

Impaired reabsorption of HCO3-

Question 15

What is the acid/base effect of elevated PTH?

Answer 15

Hyperchloremic metabolic acidosis

Question 16

What is the first line test in a hypercalcemic patient?

Answer 16

PTH level

Question 17

What is the most common cause of hypercalcemia in ambulatory patients? What about hospitalized patients?

Answer 17

Ambulatory= Hyperparathyroidism

Hospitalized= malignancy

Question 18

What is the most common cause of primary hyperparathyroidism?

Answer 18

Single parathyroid adenoma

Question 19

What is the mnemonic to remember the major clinical features of primary hyperPTH?

Answer 19

• Bones= long bone pain
• Stones= kidney stones
• Groans= gastric ulcers
• Moans= psychiatric sx. -depression

Question 20

What are the expected labs for hyperPTH?

Answer 20

• Increased Ca++ (chronic)
• Decreased phosphate
• Increased or normal iPTH*
• Increased urine Ca++

Question 21

Generally, how does hyperPTH effect bone?

Answer 21

Decreased bone density, especially in cortical bone

Question 22

What bone must be checked for a DEXA scan with likely hyperPTH?

Answer 22

Wrist

Hip/spine is different type of bone that is not usually as implicated in the osteoporosis caused by hyperPTH

Question 23

What is the definitive treatment for primary hyperPTH?

Answer 23

Surgery

Question 24

What are the indications for surgery in primary hyperPTH?

Answer 24

1) Symptoms
2) Serum Ca++ greater than 1 over upper normal limit
3) Creatinine clearance less than 70%
4) Less than 50 y/o

Question 25

What are the complications of surgery in primary hyperPTH?

Answer 25

1) Recurrent laryngeal nerve damage
2) Hypocalcemia
3) Hungry bone syndrome

Question 26

What is hungry bone syndrome?

Answer 26

• Severe disease drastically drives Ca++ OUT of bones
• That drive is removed
• Bones react by “mopping up” Ca++ as PTH drive stops

*Results in severe acute cases of hypocalcemia

Question 27

What are the medical therapies for primary hyperPTH?

Answer 27

1) Avoid dehydration
- No diuretics
- H20
2) Bisphosphonates (decrease bone turnover)
3) Calcimimetics
4) Monitoring with Ca++, creatinine, DEXA

Question 28

What are the most common causes of secondary hyperPTH?

Answer 28

1) Vitamin D deficiency

2) Renal failure

Question 29

What causes tertiary hyperparathyroidism?

Answer 29

Renal failure

*This is when there are renal failure leads to autonomously functioning parathyroid glands

Question 30

What is FHH?

Answer 30

Familial Hypocalciuric Hypercalcemia

Question 31

What is Familial Hypocalciuric Hypercalcemia?

Answer 31

• Inactivating mutation of Ca++ receptor
• Mild hypercalcemia/ iPTH
• Low urinary Ca++

Question 32

Is treatment indicated for FHH?

Answer 32

NO

Question 33

What are the basic causes of hypoPTH?

Answer 33

1) Low PTH production

2) Resistance to PTH (receptor level problem)

Question 34

What is the most common cause of hypoPTH?

Answer 34

Surgical excision

Question 35

What are the symptoms of hypoPTH dependent on?

Answer 35

The DEGREE and RAPIDITY of hypocalcemia

Question 36

What are the major sx. associated with hypoPTH?

Answer 36

asdf

Pathoma

Question 37

What are the net physiologic effects of hypoPTH?

Answer 37

• Decreased Ca++

- Increased phosphate

Question 38

What cancer is associated with hypocalcemia?

Answer 38

Prostate cancer i.e. an “osteoblastic metastasis”

Question 39

What do you need to correct a serum Ca++ for?

Answer 39

Serum albumin

• Albumin greater than 4= lower Ca++
• Albumin less than 4= higher Ca++

Question 40

How should you approach hypocalcemia?

Answer 40

1) Measure iPTH
2) Measure Vitamin D
3) Measure Mg++

Question 41

How is hypocalcemia treated?

Answer 41

1) IV or PO calcium
2) Vitamin D

AND
3) Synthetic PTH analog (NATPARA)

*Note expensive and subQ; good for non-compliant patients

Question 42

What are the two types of pseudo pseudohypoPTH?

Answer 42

Types 1A and 1B

*Both are problems with end-organ resistance to PTH

Question 43

What are the labs associated with Type 1A and 1B pseudohypoPTH?

Answer 43

1) Low Ca++
2) High Phosphate
3) High iPTH

Question 44

What is the major difference between pseudohypoPTH 1A and 1B?

Answer 44

No physical manifestations

Question 45

What is pseudo pseudohypoparathyroidism?

Answer 45

Physical manifestations without lab abnormalities