Article 6 male female 5 human 5 liquid chromatography-mass spectrometry 5 adult 4 controlled study 4 aged 3 high performance liquid chromatography 3 solid phase extraction 3 solid phase microextraction 3 Female 2 Humans 2 Male 2 Plasma 2 animal experiment 2 animal model 2 animal tissue 2 biological marker 2 blood 2 classification 2 comparative study 2 creatine 2 follow up 2 in vivo study 2 limit of detection 2 limit of quantitation 2 major clinical study 2 mass spectrometry 2 measurement accuracy 2