Metal Levels in Blood, Urine, and Hair May Serve as ALS Biomarkers, Study Suggests
Several metals may be linked to the risk of amyotrophic lateral sclerosis (ALS), according to results of a small study in Italy. The findings state that levels of metals and other essential trace elements in blood, urine, and hair may serve as biomarkers to diagnose and monitor ALS.
The study titled, “Essential trace elements in amyotrophic lateral sclerosis (ALS): Results in a population of a risk area of Italy,” was published in the journal Neurological Sciences.
The Italian island of Sardinia has a particularly high incidence of hereditary ALS among the local population. Researchers examined levels of several trace elements — mostly metals — including calcium, zinc, iron, magnesium, selenium, and copper, to investigate whether different concentrations were related to the incidence of ALS on the island.
“Few studies have evaluated deficiency or overload of essential elements in ALS using levels directly measured in human fluids and tissues of patients,” wrote Giovanni Forte, from the Istituto Superiore di Sanità, in Rome, Italy, and his research colleagues. “In addition, no previous study was performed in Sardinia Island to associate body levels of essential elements to the higher frequency of ALS in this Italian area.”
The team evaluated element levels using blood, urine, and hair samples from 34 ALS patients (with a mean age of 62 years) and 30 age- and gender-matched healthy controls.
In blood samples, the levels of calcium and copper were significantly increased in ALS patients compared to healthy individuals. In hair, selenium and zinc were significantly increased in ALS patients. Urinary levels of magnesium and selenium, however, were significantly decreased in these patients.
The study also revealed that women with ALS had higher calcium levels than healthy men and men with ALS. Copper levels also were higher in ALS women than in ALS men. But blood iron and magnesium levels were lower in women than in healthy men and men with ALS. Selenium levels were negatively correlated with increased age.
Copper levels were found to be associated with older age, disease duration, and body mass index in patients. Researchers also identified certain correlations between the levels of multiple elements. For example, levels of selenium/calcium and selenium/zinc were positively correlated, while levels of calcium/magnesium and calcium/zinc were negatively correlated (when one was increased, the other was decreased). This suggests that ALS may develop based on specific associations between metals present in the body.
“Elements that present deficiency in the body or that exceed a certain level, and abnormalities in interactions between elements could be important biomarkers for assessing the ALS status in patients,” researchers wrote. “We found higher concentrations of Ca and Cu in blood and Se and Zn in hair in cases with respect to controls, while urinary excretion of Mg and Se was lower in patients. Despite the clinical heterogeneity among patients, our results suggested that … these biomarkers might distinguish between patients with or without ALS, with sufficient sensitivity and specificity.”