Mechanism of osteopenia: vitamin A stimulate osteoclasts to increase bone resorption
Patients who may be at risk for vitamin A (retinoid) associated osteopenia:
(1) people receiving vitamin A supplements for malabsorption (cystic fibrosis, pancreatic insufficiency, short bowel syndrome, etc) or in parenteral nutrition
(2) vitamin enthusiasts who take excessive amounts of vitamin A
(3) people receiving isotretinoin for acne
(4) postmenopausal women or other people at risk for osteoporosis who have increased vitamin A intake
(5) someone whose diet is high in liver
A patient at risk will often have elevated serum vitamin A (retinol) levels.
If a person has vitamin A associated osteopenia, then cessation of excessive intake should be followed by improved bone density, but this may take years to occur (Milstone and Milstone).
