The trick is that conventional doctors are not trained to notice it. Also, simple blood tests are not ANY simple, and ironically are not well done by conventional doctors.
Hypoglycemia is not all about just taking the blood sugar levels from blood. It is more about the progression of blood sugar levels throughout time. The peaks and falls are more important.
Regarding magnesium/calcium testing, most of magnesium is stored inside the cells (intracellular) so it won't show on simple blood tests.
Before you continue to disregard the nutritional aspect of mental disorders please take a read at http://www.hypoglycemia.asn.au
and the links posted in the first post of this topic (they can explain you a lot, too). It is far more complex than you can believe.
Thanks for reading.