Comparative assessment of blood Metal/metalloid levels, clinical heterogeneity, and disease severity in amyotrophic lateral sclerosis patients

•Blood metal/metalloid levels in ALS differ from control in North Western China.•Spinal and bulbar onset contain different characteristics of metal/metalloid levels.•Cu and Fe levels are found high in ALS patients, particularly for spinal onset.•Bulbar patients show significantly higher Ca levels than spinal onset patients.•Cd, Pb, Cu, and Ca levels are positively correlated with high ALS severity.