Women, Menopause and Osteoporosis

We all know that women are at a very high risk of osteoporosis after menopause, but the question is why? Well the easy answer is no estrogen. This will not cut it for the boards. So you may know all of this already but it can't hurt to review it and let me know if I made a mistake.

Osteoporosis = The body breaks more bone down than it builds. 

So we have osteoblasts which build bone. We have osteoclasts which break bone down for the calcium and put the calcium into the blood. We have 2 important receptors on our Osteoblasts (I am sure there are many more than 2). One receptor = is for Vitamin D. Vitamin D hooks into the receptor and causes the enzyme Alkaline Phosphatase to be released. So whenever we are building or making bone we should have an elevated alkaline phosphatase level. 

The other receptor on the osteoblasts is a receptor for PTH. Now when PTH hooks into its receptor on the osteoblasts it releases IL-1 (also known for fevers, stimulating antibody synthesis, B-cell stimulation etc) in this case IL-1 is called osteoclast activating factor. IL-1 goes over to the osteoclasts and stimulates them to start breaking bone down, which they do and this raises are blood calcium levels. So when we need calcium, this is a good thing. Normally IL-1 is kept in check by our sex hormones, like testosterone in men and estrogen in women. The estrogen blocks the IL-1 from going too crazy. 

After menopause when women do not have any more estrogen or in athletes or anorexics who have low levels of estrogen there is nothing to inhibit IL-1 and it over stimulates the osteoclasts and they breakdown too much bone and you get a pathologic fracture of the hip, get hospitalized and get nosocomial pneumonia and die!

That is why postmenopausal women get osteoporosis. 

Shout out to Goljan!