Serum dopamine beta-hydroxylase (D beta H) levels during tilting in patients with spinal cord injuries

The activity of dopamine-beta-hydroxylase (D beta H) in the serum was measured in patients with quadriplegia and in healthy subjects. We assume that the plasma D beta H levels reflect sympathetic tone. Quadriplegics had significantly lower D beta H levels at rest. After head-up tilting a significant decrease in D beta H levels occurred in patients with spinal cord injury suggesting failure of the sympathetic nervous system. However, a considerable overlap exists between normals and quadriplegics, making this test of limited value in the assessment of autonomic function in individual subjects.