Plasma or serum zinc levels are the most commonly used indices for evaluating zinc deficiency, but these levels do not necessarily reflect
cellular zinc status due to tight homeostatic control mechanisms [8].
Kajanachumpol, S., Srisurapanon, S., Supanit, I., Roongpisuthipong, C., and Apibal, S. Effect of
zinc supplementation on
zinc status, copper
status and
cellular immunity in elderly patients with diabetes mellitus.