Bone Health Flashcards
How plasma Ca2+ is regulated
Calcitriol (activated Vit D) and PTH maintain plasma Ca2+ and prevent hypocalcemia neuromuscular tetany
Non-VitD Rickets
If dietary Ca2+ is too low, then the internal adaptation cannot occur and Rickets will develop without VitD deficiency.
Pathogenesis of Normal VitD Rickets
Low dietary Ca2+ and high phytate and oxalate –>
Inadequate Ca2+ absorption for skeletal growth –>
Decreased plasma Ca2+ –>
Increased Serum PTH –>
Dear Serum Pi and increased 1,25OH2VitD
Causes mineralization defects, and hyperosteoidodis–>
Rickets and osteomalacia
Hyperosteoidosis
increased amount of unmineralized bone matrix
Dietary acid and bone health
Bone demineralization occurs with lowered pH.
Fruits and vegetables can buffer the dietary acid with their K+ salts of HCO3- and weak organic acids.
Increased acidity causes bone resorption by osteoclasts
Ability to excrete acid declines with age–> decreasing pH and increasing risk for bone loss/breaks
KHCO3 supplementation
Improves Ca2+ and PO4 balance which improves bone health.
Carbonated mineral water also does this.
Ca citrate/malate supplements
Supply alkali and increase bone health
Vitamin D
Regulates Ca2+ and PO4 homeostasis.
Comes from sunlight or diet
Activated by 1-a-hydroxylase in the Kidney epithelial cells.
Foods with VitD
Oily fish (herring, salmon)
Cod and halibut liver oils
Butter, cream and cheese
Fortified breakfast cereals
Causes of Vitamin D Deficiency
Reduced skin synth
Decreased bioavailability
Increased catabolism
Decreased synth of 25-OHVitD (liver disease)
Increased urinary loss of 25-OH
Decreased synth of 1,25-OH (kidney disease)
Consequences of Vit D Deficiency
HTN Osteoporosis and fracture Decr. m. strength and increased falls CVD Cancer: colon, prostate, breast AI Diseases: osteoarthritis, DM-I, psoriasis, wheezing illness, lung fxn TB Schizophrenia Depression
