How many years do you need to study to become a doctor? And what is different between an intern, resident, fellow ect...?

12 years of school, four years of college and four years of medical school.

The first year of training after medical school is called an internship, or more commonly it is called first year of residency or PGY-1 (Post-Graduate Year-1). The following years are called PGY-2, PGY-3, etc. The training that is done after a residency (in a subspecialty) is usually called a fellowship. Much of what you will learn in your chosen specialty will be learned in your residency.

b

Explanation:

bone erosion would cause hormonal secretion's that decrease the absorption of calcium.

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