All of the following are the known causes of osteoporosis except :
Answer is A (Fluorosis): Fluorosis is associated with `Osteosclerosis' and not with osteoporosis. Hypogonodism, Hypehyrodism and Hyperparathyrodism are all known causes for osteoporosis.
Fluorosis
Hypogonadism
Hypehyroidism
Hyperparathyroidism