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