Metabolic & Vascular Bone Diseases Flashcards
(Mild/Severe) decreases in serum Ca++ is compensated by increased bone resorption activity at the Lining Cell/Osteocyte Complexes (LCOC’s)
Mild
(Mild/Severe) decreases in serum Ca++ is compensated by additional Bone Multicellular Units (BMU’s) (clusters of osteoclasts and osteoblasts); however this can impair the structural integrity of the bone
Severe
What are the 2 hormones in control of Calcium Homeostasis
PTH
Vitamin D3
A hormone released from chief cells within the PT gland in response to decreases in serum Ca+2; inhibited by Vitamin D
Parathyroid Hormone
Describe how PTH increase serum Ca+2 levels
- PTH binds to receptors on osteoblasts
- Osteoblasts secret RANKL (osteoclast activating factor)
- RANKL binds to RANK receptors on osteoclasts for activation
- Bone resorption at LCOC and BMU releases Ca+2
A steroid hormone synthesized in inactive from in skin under sun exposure; increased availability of Ca+2 and PO43- for mineralization; enhances monocyte immune response
Vitamin D3
Vitamin D3 is activated by
liver and kidney (PRT)
Primary hyperparathyroidism is caused by
adenoma
Lab findings of Primary hyperparathyroidism
High Ca+2
High PTH
High Alk Phos
(Primary/Secondary) Hyperparathyroidism presents with symptoms of HYPERcalcemia –> kidney sones, GI symptoms, high bone turnover, fatigue
Primary
Secondary hyperparathyroidism is caused by
renal disease, vitamin D deficiency, corticosteroids
Lab findings of secondary hyperparathyroidism
Low Ca+2
High PTH
High Alk Phos
T/F
Unlike primary hyperparathyroidism, hypercalcemia symptoms are NOT present in secondary hyperparathyroidism
True
The most common cause of Secondary Hyperparathyroidism
Renal Osteodystrophy
- Can’t activate Vit D
- Can’t excrete phosphate
Describe how renal osteodystrophy cause secondary hyperparathyroidism
- Decreased phosphate excretion –> serum phosphate binds to serum Ca+2 –> low serum Ca+2
- Vitamin D cannot be activated –> further decreased serum Ca+
- In response to low Ca+2, PTH is increased
A bone disorder in which bones are soft and flexible; caused by defective mineralization due to vitamin D deficiency; has calcium-phosphorous cross product of <30
Osteomalacia (rickets)
Bowed legs, rachitic rosary (enlarged anterior ribs), physeal widening, and metaphyseal flare are findings of
rickets
T/F
Osteoporosis, osteogenesis imperfecta, osteopetrosis, and paget disease will present with serum calcium abnormalities
False; they have normal serum Ca+2
A bone disorder that has normal mineralization but decreased bone quantity; normal Ca+2 and PO43-; increased radiolucency on x-ray
Osteoporosis
Primary Osteoporosis is divided into what two categories?
Postmenopausal (Type 1)
Age-related (Type 2)
Type of PRIMARY Osteoporosis; more TRABECULAR than cortical involvement; presents with distal radius fractures (colle’s fractures) and vertebral fractures
Postmenopausal Osteoporosis
Type of PRIMARY Osteoporosis; equal Trabecular and Cortical involvement; presents with proximal femur and vertebral fractures
Age-related osteoporosis
(Primary/Secondary) Osteoporosis is due to steroids, parathyroid disease, or hyperthyroidism (activates osteoclast stimulation)
Secondary
A disorder of bone formation that is also known as “brittle bone”
Osteogenesis Imperfecta
Osteogenesis Imperfecta is caused by a defect in
Type I collagen
Signs of Osteogenesis Imperfecta
- Blue sclera
- Hearing loss (ear bones)
- tooth abnormalities
- Multiple fractures
A disorder of bone resorption that is also known as stone/marble bone; hardened bones due to osteoclast failure
Osteopetrosis
“Erlenmeyer flask” appearance on X-ray and marrow cavity loss on histology is indicative of which intrinsic bone disease
Osteopetrosis
A disorder of bone remodeling; elevated alk phos due to increased osteoclast fxn; lead to fragile or deformed bones
Paget Disease
Mixed mature and immature bone (Cement or “Mosaic” lines) can be indicative of which Bone Disease
Paget Disease
Moth-eaten radiographic appearance is indicative of which Bone Disease
Paget Disease
What Bone Disease can degenerate into Osteosarcoma?
Paget Disease
Avascular necrosis of hip is known as
Hip osteonecrosis
Avascular necrosis of the Femoral head is usually due to disruption of blood flow via what vessel?
Medial Femoral Circumflex artery
Rare CHILDHOOD condition that affects the hip; blood supply to the head of the femur is temporarily disrupted and bone cells die
Perthes disease
Hip avascular necrosis has a relationship to prior ___________use
corticosteroid
What bone disorder causes cystic changes on x-ray due to high bone turnover seen in hyperparathyroidism?
Osteitis fibrosa cystica
