Can you see all magnesium metabolism disorders also from blood sample test, or only from 24 hour urine test?

Whoa: Magnesium disorders are poorly understood and probably uncommon. You can't diagnose them by blood work, or even by any simple urine labs. Who's telling you this? Have you considered getting a second opinion? You're a well-intentioned but perhaps vulnerable person -- is someone trying to take advantage of you? Please get with someone honest, perhaps a trustworthy holist in your community.