Pituitary & Calcium Flashcards
describe the growth hormone axis
hypothalamus produces growth hormone releasing hormone (GHRH); stimulates pit to release growth hormone; stimulates liver & other tissues to release insulin-like growth factor I (IGF-1) that mediates the growth effects of GH
*hypothalamus can also produce somatostatin releasing inhibitory hormone (SRIH) to inhibit GH
What is used to treat hyperprolactinemia?
dopamine agonist b/c it inhibits prolactin secretion
Which two hormones are structurally homologous and have homologous receptors?
GH & prolactin
modeling of bone
formation/deposition of new bone
remodeling of bone
turnover (breakdown & renewal) of existing bone via osteoclasts & osteoblasts
*not 100% efficient
How do glucocorticoids affect calcium homeostasis?
cause osteoporosis
- -prevent absorption of Ca from GI tract
- -promote movement of Ca from bone
Which drugs inhibit movement of Ca from bone to the serum?
estrogens
SERMs
calcitonin
bisphosphonates
What is hydroxyapatite?
the component of bone that needs to be dissolved for remodeling of bone to occur
mechanism of action of bisphosphonates
taken up by osteoclasts; inhibit **geranylgeranyl diphosphate synthase involved in soprenoid biosynthesis; inhibits bone resorption
Which drugs can cause drug-induced osteoporosis?
glucocorticoids
What is RANK?
receptor-ligand complex involved in resorption of bone; RANK is a receptor on osteoclasts; osteoblasts produce hormone RANKL; binds to stimulate osteoclasts to resorb the bone
causes of hypocalcemia
dietary deficiency
Vit D deficiency
metabolic rickets, osteomalacia
hypoparathyroidism, pseudohypoparathyroidism
causes of hypercalcemia
hyperparathyroidism ectopic PTH production Vit D excess body immobilization so increased remodeling *tx w/ calcitonin & bisphosphonates
