A rapid fall in blood glucose levels or the hypothalamic sensing of neuroglycopenia causes the release of the counterregulatory hormones, primarily the catecholamines epinephrine and norepinephrine. The release of the latter is responsible for the hyperepinephrinemic findings, including anxiety, nervousness, irritability, nausea, vomiting, palpitations, and tremor. Such signs and symptoms were noted in 8 percent of ED patients with hypoglycemia. 4
The term "hyperepinephrinemic" is a misnomer in that cholinergic factors resulting from autonomic nervous system stimulation are also noted in certain patients. Stimulation of the cholinergic nervous system also occurs and may result in manifestations such as sweating, changes in pupillary size, bradycardia, and salivation.
The rapidity of onset of the hypoglycemic event determines in part the presentation. A gradual onset of hypoglycemia results from a relatively slow decrease in the serum glucose and the development of the neuroglycopenic signs and symptoms. Conversely, a sudden drop in the blood sugar level will produce anxiety, diaphoresis, tremor, and the other hyperepinephrinemic findings. In most cases of hypoglycemia, however, CNS dysfunction predominates with some degree of alteration in the level of awareness, accompanied by diaphoresis and tachycardia.
Hypoglycemia has been misdiagnosed as stroke, transient ischemic attack, seizure disorder, traumatic head injury, brain tumor, narcolepsy, multiple sclerosis, psychosis, sympathomimetic drug ingestion, hysteria, altered sleep patterns and nightmares, and depression. -l8,9,1.. and l1 Although uncommon, bradycardia has also been reported.12
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