Calcium Metabolism 1 Flashcards
What is the difference between Vitamin D2 and D3?
D2 is from plants, D3 is from animals.
Where is 1α-hydroxylase produced normally?
In the kidneys
Where can 1α-hydroxylase be produced ectopically?
In the lungs in sarcoid patients
What is the result of ectopic 1α-hydroxylase secretion?
Uncontrolled calcium regulation
What can exacerbate poor calcium control?
Taking Vitamin D supplements
What are the values of normal calcium?
2.2-2.6mmol/L
What are the values of normal corrected calcium?
8.5-10.2 mg/dL
What is the difference between calcium and corrected calcium?
Corrected calcium takes into account serum albumin
e.g. low albumin, free calcium would appear normal, but bound calcium would be low.
What is the difference between Vitamin D and PTH in terms of phosphate absorption?
Vitamin D causes both increased calcium AND phosphate absorption
PTH causes increased calcium only (phosphate trashing hormone)
Which genes do the Vitamin D receptors control?
Genes for proliferation and immune system
What is Vitamin D deficiency associated with?
Cancer
Autoimmune disease
Metabolic syndrome
What is the explanation for Vitamin D deficiency associated diseases?
Vitamin D deficiency is associated with poverty:
Poor nutrition, more drug problems, diabetes, TB, cancer etc.
What is the difference between osteoporosis and osteomalacia?
Osteoporosis is normal and ratios are correct.
Osteomalacia is a disease and caused by Vitamin D deficiency
(low Ca2+, Pi, raised ALP)
What X-Ray feature is associated with osteomalacia?
Looser Zones
Which drugs can cause increased Vitamin D metabolism (and ARDS)?
Anticonvulsants since they are potent first class metabolites
Induce liver enzymes resulting in increased Vitamin D metabolism
