Test 3 - Schricker

Question 1

Major causes of Hypercalcemia

Answer 1

1. Primary hyperparathyroidism
2. Malignant disease
3. Latrogenic Vitamin D

Question 2

Major treatments for Hypercalcemia

Answer 2

Treatment with bisphosphonates (inhibit osteoclast activity)

Question 3

What is an indication of hyperparathyroidism?

Answer 3

Intact parathyroid hormone

Question 4

What is the primary cause of hypercalcemia?

Answer 4

Parathyroid Hormone-Related Protein

Question 5

What is PTHrP produced by?

Answer 5

Tumors

Question 6

What are common tumors that produce PTHrP?

Answer 6

Breast, Lung, Kidney, Other Solid Tumors

Question 7

Major causes of Hypocalcemia?

Answer 7

Drop in Serum Albumin (adjusted calcium levels)

Question 8

Major treatments of Hypocalcemia

Answer 8

Activate osteoclast activity

Question 9

T/F: There is an abnormal metabolism of Vitamin D associated with Hypocalcemia?

Answer 9

True

Question 10

Osteoporosis

1. What is it?
2. Risk factors?
3. Treatment

Answer 10

1. Loss of mineral density with age (peak density at 30), increase fractures,
2. Risk factors: female, smoke, excessive exercise, no exercise, too much caffeine, poor diet
3. Treatment: estrogen, biphosphates, calcitonin, PTH

Question 11

Paget’s Disease

1. Characteristics
2. Symptoms
3. Cause
4. Treatments

Answer 11

1. Large, numerous Osteoclasts. Many Osteoblasts and an increase in alkaline phosphatase.
2. Symptoms: Large, misshapen bones, less dense/brittle - high serum content of hydroxyproline, pyridinolines, and telopeptides
3. Cause is unknown. Maybe genetic or early childhood viral infection.
4. Treatments: Bisphosphonates and calcitonin

Question 12

Osteomalacis

1. What does it cause?
2. Associated issue

Answer 12

1. Defects in Hydroxyapatite formation due to vitamin D deficiency
2. Rickets

Question 13

What is Rickets?

Answer 13

Bone and Muscle weakness/skeletal deformity. Due to inhibited Vitamin D metabolism

Noticed during the industrial revolution - lack of sunlight due to pollution and narrow alleys

Treatment - Cod Liver Oil

Question 14

What will you notice on teeth because of Rickets?

Answer 14

The dentin will have “gaps” since it does not remodel like bone

Question 15

What is the mineral component of bone?

Answer 15

Hydroxyapatite C10[PO4]6[OH]2; 50-60%

Question 16

What is the primary protein component of bone?

Answer 16

Collagen

Question 17

How do the remodeling cycle and serum calcium levels affect one another

Answer 17

Decreases bone mass/ increase bone reabsorption = increase calcium in serum

Question 18

Where else is calcium found?

Answer 18

Bound to Albumin

Question 19

How is calcium distributed in the serum?

Answer 19

Ionized Calcium - 50%
Protein Bound (Albumin) Calcium - 40%
Citrate or Phosphate Bound Calcium - 10%

Question 20

What Factors Regulate the Bone Remodeling Cycle?

Answer 20

Serum calcium, hormones, and cytokines

Question 21

What cells are involved in bone remodeling?

Answer 21

Osteoblasts Build Bone

Osteoclasts Resorb Bone

Question 22

How do RANK, RANKL, OPG, and Estrogen regulate osteoclasts?

Answer 22

Estrogen is a precursor for Osteoprogenerin (OPG).

OPG can bind to RANKL which inhibits it from binding to RANK (this inhibits osteoclasts)

RANKL and RANK binding together will stimulate osteoclasts

Question 23

How do osteoblasts regulate osteoclasts?

Answer 23

Osteoblast release RANKL ligand that stimulate RANK receptor and stimulates osteoclast formation

Question 24

What are the major consequences of increased PTH?

Answer 24

1. Increases serum calcium and decreases serum phosphate
2. Increases calcium reabsorption in the kidneys
3. Stimulates osteoclasts
4. Increases absorption in the small intestine

Question 25

What regulates PTH production?

Answer 25

Triggered by low plasma Ca levels

Question 26

What are the consequences of increased Vitamin D?

Answer 26

Increases serum calcium, increases bone adsorption

Question 27

What regulates Vitamin D Production?

Answer 27

Sunlight → precursors synthesized in the skin Liver = Stores Vitamin D Kidney = Conversion of Vitamin D to active form occurs 1alpha-hydroxylase is the point of regulation