Toxic and essential metals have been implicated in the pathogenesis of sporadic
motor neuron disease (
SMND), but attempts to measure blood levels of these metals have led to contradictory results. We, therefore, measured blood 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,
copper,
zinc and
selenium levels were measured in blood, plasma and red cells with inductively coupled plasma mass spectrometry and
manganese levels with atomic absorption spectrophotometry. Results were analysed using non-parametric tests. Hypo-osmotic red blood cellfragility was estimated in six
SMND/control 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 levels were significantly different, though plasma lead in
SMND had a tendency to be higher than controls. No difference in red cell fragility was found between groups. In conclusion, plasma levels of
cadmium were raised in this
SMND group, but the
biological significance of this is uncertain. The measurement of metals in the blood of
SMND cases seems unwarrranted for routine diagnostic testing.