Decreased copper level in the blood serum of male stutterers and the occurrence of the vibratio brevis phenomenon.

The blood serum copper level and the phonation start were investigated in sixteen male subjects with developmental stuttering (mean age = 25.8 years). A statistically significant decrease in blood serum copper level was revealed in the stutterers under study. The differences between their mode and mean values and that of the control group were 4.6 mumol/l and 3.1 mumol/l, respectively. The negative linear regression between the copper level in serum and the vibratio brevis phenomenon was registered in the stutterers under study. A decreased copper level can be involved in the biochemical abnormalities of male developmental stutterers and it can be included among the factors participating in pathophysiology of an uncertain phonation start.