Final answer:
The most common cause of autonomic dysreflexia (hyperreflexia) is urinary retention. It is a severe response that occurs due to improper nervous system regulation of bladder control after a spinal cord injury.
Step-by-step explanation:
Autonomic dysreflexia, also known as hyperreflexia, can be a life-threatening complication of spinal cord injury. The most common precipitating cause of autonomic dysreflexia is urinary retention. This condition arises when the nervous system, which controls the urinary system, fails to regulate urination properly, leading to an inability to empty the bladder. This can trigger an excessive response from the autonomic nervous system, resulting in severe high blood pressure and other symptoms. While issues such as elevated blood glucose levels can contribute to neurological deficits, particularly in diabetes, they are not the direct precipitants of autonomic dysreflexia. Similarly, respiratory distress can be a consequence but is not the primary cause of this condition.