Calcium Metabolism Flashcards
Name 3 effects of vitamin D
Increase calcium phosphate intestinal absorption
Increase calcium phosphate renal absorption
Decrease PTH expression
Would you administer vitamin D in instances of secondary hyperparathyroidism?
Yes- you want to increase calcium
When do you avoid giving vitamin D due to risk of metastatic calcification?
In the presence of hyperphosphatemia
What is the MOA of the bisphosphonates?
Inhibition of farnesyl pyrophosphate synthase –> decreased protein farnesylation, decreased osteoclast activity and decreased bone resorption
When do you administer bisphosphonates?
Disease with increased bone resorption: Osteoporosis Paget's disease of the bone Hypercalcemia Metastatic bone disease Osteogenesis Imperfecta
What is the MOA of denosumab?
mAB against RANKL –> no activation of osteoclasts
Denosumab; indications?
Osteoporosis (High fracture risk) Hypercalcemia of malignancy refractory to bisphosphonates Giant Cell tumor of the bone Metastatic bone disease
Teriparatide: MOA?
PTH receptor agonist
Intermittent activity
-Stimulates osteoblasts
-Promotes bone growth
Without stimulating osteoclasts
Teriparatide; indications?
Osteoporosis (High fracture Risk)
- Failed other therapies
- Intolerance to bisphosphonates
Teriparatide; contraindications?
History of gout Hypercalcemia Risk of osteosarcoma: -Active malignancy of the bone -Radiation therapy of the bone -Paget’s Disease of the bone -Children /adolescents
Calcitonin: MOA?
Calcitonin Receptor agonist
Inhibits osteoclast activity
Inhibits Ca2+ reabsorption In the kidney
Calcitonin: indications?
Severe hypercalcemia
Osteoporosis (not 1st line)
Paget’s Disease of the bone In those intolerant to bisphosphonate
Bone pain associated with osteoporotic fracture
Cinacalcet: MOA?
Calcimimetic
Allosterically enhances affinity of CaSR for Ca2+
Inhibits PTH expression
Cinacalcet: indications?
Primary hyperparathyroidism
Secondary hyperparathyroidism due to CKD (on dialysis)
Hypercalcemia associated with parathyroid carcinoma
Sevelamer: MOA?
Cationic polymer
Binds phosphate in GI tract & blocks absorption
Lowers serum phosphate without affecting Ca2+
