Quiz 3: Bones

Question 1

Terminology: Formation, Breakdown, Remodeling/Turnover

Answer 1

Osteogenesis: new bone formation
Resorption: absorption of old bone
Remodeling or Turnover: Reshaping –Depositing (formation) and absorbing (breakdown) bone to make new bone

Question 2

Regulation of Ca, PO4 and Bone Metabolism

Answer 2

Three Hormones:
Parathyroid Hormone (PTH)
Vitamin D
Calcitonin

Question 3

Bone Types

Answer 3

Cortical: primary type in long bones, Strong and rigid
Trabecular: primary type in axial skeleton like the vertebrae, Numerous cross-hairs, Strength and elasticity
Mixtures of the two: Femoral neck, Distal radius

Question 4

Bone Assays

Answer 4

Calcium
Phosphate
Magnesium
Alkaline Phosphatase
PTH
Vitamin D	
Calcitonin
Bone Markers

Question 5

Bone Composition

Answer 5

• Mineral: Ca & PO4 in hydroxyapatite crystals
• Collagen fibers– 25% hydroxyproline or proline
• Cells:
  + Osteoblasts: make new bone matrix
  + Osteocytes: regulatory functions
  + Osteoclasts: phagocytic cells that respond to PTH for resorption: contain enzymes to demineralize & digest bone

Question 6

Bone Turnover Markers

Answer 6

Identify and Monitor Patients at Risk for significant bone loss
Monitor compliance of therapy
Monitor Progress of Anti-resorptive treatment (before bone density improves): Faster than bone scan, compliance, adjust medication levels

Question 7

Patients at risk for bone loss

Answer 7

Post-menopausal women
Metabolic bone diseases
Renal diseases
Malnutrition
Chronic alcoholism
Low physical activity & immobility
Medications
Premenopausal amenorrhea
Hypogonadism
GNRH therapy (endometriosis)
Thyrotoxicosis
Hyperparathyroidism
VitaminD deficiency

Question 8

2 Main Bone Markers

Answer 8

1. Resorption: C-Telopeptide (CTx)

2. Formation: Type 1 Procollagen C terminal Propeptide (P1CP)

Question 9

Osteocalcin

Answer 9

1% of total protein in bone.
Synthesized by osteoblasts (cells that form bone)
Plasma levels reflect osteoblast activity

Question 10

Osteocalcin Measurement and Levels

Answer 10

Immunoassay
Serum = male 3 - 13 ng/mL
female premenopausal 0.4 - 8.2 ng/mL, postmenopausal 1.5 - 11.0 ng/mL
Levels reflect bone formation

Question 11

Osteoporosis

Answer 11

Primary: postmenopausal
Secondary : malnutrition, drugs, alcoholism, or metabolic disease
44 Million Americans at risk
Female: Male 4: 1
1.5 Million Fracture/year in US ($19 billion): Vertebral Compressions, Hip, Distal Forearm
40-50% lifetime risk for Caucasian Women

Question 12

Osteomalacia (rickets in children)

Answer 12

Rickets: Children: Low Vitamin D
Adults: low Vit D, Ca, PO4, Impaired mineralization

Question 13

Osteitis Fibrosa

Answer 13

Hyperparathyroidism (PTH elevated)

Renal failure

Question 14

Osteoporosis Treatment

Answer 14

Treat Fracture
Modify preventable Risk factors: smoking, alcohol, risk of falls, walkers, bedrails, etc
Add dietary Ca and Vitamin D
Prevention for family members: Exercise, diet
Medications

Question 15

Osteoporosis Medication

Answer 15

Slow Bone Loss (Reduces resorption): Bisphosphonates.
SERMS: selective estrogen receptor modulators
Hormones: Calcitonin, Estrogen
Bone Formation and Reduces resorption
Teriparatide (Forteo). This powerful drug, an analog of parathyroid hormone. It works by stimulating new bone growth

Question 16

Paget’s Disease

Answer 16

• Aggressive osteoclast-mediated bone resorption preceding imperfect osteoblast-mediated bone repair.
• Thickening and hypertrophy of long bones and deformity of flat bones
• Presents with bone softening, pain, fractures, bone deformity
• Detected by radiography and very elevated serum ALP. Ca usually normal.

Question 17

Paget’s Disease Treatment

Answer 17

Pharmacological treatment includes bisphosphonates (bind to and inhibit calcium) and calcitonin.
Additional drugs as required for pain and inflammation.