Dr. JACK wrote:
The most common causes of rickets we see in 4-10 year olds, at least in
my experience, are renal disease, inflammatory bowel disease or
malabsorption problems, and metabolic problems.  Except where a child
has been starved and kept in a locked cupboard, I cannot imagine a child
getting vitamin D deficiency rickets in our society.  It must be
virtually unheard of here.

Sorry for being obscure Jack, when I "see rickets" it is usually in the
skeltons from a prehistoric Native American population for northern US
states.  There are studies showing a higher incidenced of rickets in
northern US states compared to southern, and if divided by "race" then the
highest incidence is in northern US African-American populations, and the
lowest in southern US "whites".  Cows' milk is the main source of calcium in
US diets, unfortunately, and it is all fortified with Vitamin D in the US,
but most of the world is lactose intolerant after late childhood, so many
people don't drink it much.
Katherine A. Dettwyler, Ph.D.
Associate Professor of Anthropology and Nutrition
Texas A&M University