Zinc deficiencies are not that uncommon.
Especially for 16 year-old males.
Not sure what your point is.
The fact is that zinc is needed for sexual maturity. Zinc deficiencies are known to cause problems during childhood because zinc is also important for growth. But a zinc deficiency can also cause symptoms to develop during adolescence because of the need for extra zinc for sexual maturation. At 16 a boy needs more zinc than say a 22 year old male needs because of the increase in sexual hormones during puberty.
Signs of zinc deficiency include growth retardation, hair loss, diarrhea, delayed sexual maturation ...
http://dietary-suppl...ts/cc/zinc.html