Measuring blood calcium levels is not an accurate indicator of total body calcium because

A. blood calcium levels are strictly controlled by hormones and do not reflect total body stores.
B. calcium in the blood reflects only the most recent dietary intake of calcium.
C. blood calcium levels vary according to the intake of other positive ions (e.g., sodium, potassium, and magnesium).
D. there are no reliable tests for measuring blood calcium.


ANSWER:

A. blood calcium levels are strictly controlled by hormones and do not reflect total body stores.