To determine if blood metal levels of selenium (Se), mercury (Hg), methylmercury (MeHg), manganese (Mg), lead (Pb), and cadmium (Cd) in ALS patients in the National Amyotrophic Lateral Sclerosis (ALS) Biorepository are different than participants in the National Health and Nutrition Examination Survey (NHANES). 

ALS is a fast progressive, neurodegenerative disease. ATSDR maintains the National ALS Registry (Registry) to examine the epidemiology and etiology of the disease. Increased blood levels of Pb and Cd have been associated with ALS.  

ATSDR’s National ALS Biorepository which started in 2011includes biospecimens from living and deceased patients. Blood metal levels for ALS patients and NHANES participants were analyzed by CDC’s National Center for Environmental Health (NCEH) laboratory, using the same assay methodologies. NHANES 2011/2012 and 2013/2014 combined cycles were used as comparison data. A binomial proportion test was used to perform comparisons between each study participant and their sex- and age matched-specific NHANES category. Selection probabilities, non-response, over-sampling, and differences between NHANES and the total US population were taken into account by using sampling weights among the median analyte measurements. We tested whether the proportion of ALS patients in the biorepository, with an analyte measurement ? the 50% percentile in NHANES participants, was significantly different than the proportion under the null hypothesis (H₀=0.50). 

Among ALS patients, the proportions of Se, Hg, Mg, Pb, and Cd in the biorepository were all ? 50% compared to NHANES except for MeHg. The proportions for Mg (0.57, 95% CI 0.52, 0.63), Pb (0.66, 95% CI 0.61, 0.71) and Se (0.70, 95% CI 0.64, 0.74) were statistically significant (p<0.05). 

Our study found higher levels of Se, Hg, Mg, Pb, and Cd in ALS patients than in NHANES participants.