Blood levels of toxic and essential metals in motor neuron disease

Toxic and essential metals have been implicated in the pathogenesis of spor adic motor neuron disease (SMND), but attempts to measure blood levels of t hese metals have led to contradictory results. We, therefore, measured bloo d levels of various metals using paired SMND/controls. In 20 subjects with SMND (15 males, five females, mean age 56.8 years) and 20 partner controls (15 females, five males, mean age 55.0 years) cadmium, lead, mercury, coppe r, zinc and selenium levels were measured in blood, plasma and red cells wi th inductively coupled plasma mass spectrometry and manganese levels with a tomic absorption spectrophotometry. Results were analysed using non-paramet ric tests. Hypoosmotic red blood cell fragility was estimated in six SMND/c ontrol pairs to see if hemolysis could account for increased metal levels. The plasma cadmium level was significantly raised in SMND cases (P = 0.005) , but with considerable overlap between SMND and controls. No other metal l evels were significantly different, though plasma lead in SMND had a tenden cy to be higher than controls. No difference in red cell fragility was foun d between groups. In conclusion, plasma levels of cadmium were raised in th is SMND group, but the biological significant of this is uncertain. The mea surement of metals in the blood of SMND cases seems unwarranted for routine diagnostic testing. (C) 2001 Published by Elsevier Science Inc.