From the Guidelines
The diagnostic approach for autonomic neuropathy involves a comprehensive evaluation beginning with a detailed medical history and physical examination focused on autonomic symptoms, as recommended by the most recent guidelines 1. The diagnosis of autonomic neuropathy is crucial for identifying the underlying cause and managing the condition effectively.
- A detailed medical history and physical examination are essential for assessing autonomic symptoms, such as orthostatic hypotension, gastroparesis, constipation, diarrhea, fecal incontinence, erectile dysfunction, neurogenic bladder, and sudomotor dysfunction 1.
- Specialized autonomic function tests, including heart rate variability testing during deep breathing and Valsalva maneuver, can evaluate cardiovascular autonomic function 1.
- Quantitative sudomotor axon reflex testing (QSART) or thermoregulatory sweat testing can assess sweat gland function, while gastrointestinal autonomic dysfunction may be evaluated through gastric emptying studies 1.
- Laboratory tests, such as blood glucose, hemoglobin A1c, vitamin B12 levels, thyroid function, and screening for autoimmune disorders, can help identify underlying causes of autonomic neuropathy 1.
- Nerve conduction studies and electromyography can differentiate autonomic from somatic neuropathies, and skin biopsies can detect small fiber neuropathy affecting autonomic nerves 1.
- Genetic testing may be appropriate when hereditary autonomic neuropathies are suspected 1. This multimodal approach is necessary because autonomic neuropathy can result from various conditions, including diabetes, autoimmune disorders, toxic exposures, and neurodegenerative diseases, each requiring specific management strategies.
- The most recent guidelines emphasize the importance of annual assessment for autonomic neuropathy in individuals with type 1 diabetes for 5 years and all individuals with type 2 diabetes 1.
- Early detection and management of autonomic neuropathy can improve quality of life and reduce morbidity and mortality associated with the condition 1.
From the Research
Diagnostic Approach for Autonomic Neuropathy
The diagnostic approach for autonomic neuropathy involves a combination of clinical evaluation, laboratory testing, and autonomic function testing.
- The autonomic medical history is key when seeing a patient with suspected autonomic neuropathy, as it guides the clinical evaluation, laboratory testing, and autonomic testing 2.
- Initial laboratory evaluation includes fasting glucose or oral glucose tolerance test, thyroid function tests, kidney function tests, vitamin-B12, serum, and urine protein electrophoresis with immunofixation 3.
- Autonomic function testing, such as the autonomic reflex screen, can assess sympathetic postganglionic sudomotor, cardiovascular sympathetic noradrenergic, and cardiac parasympathetic function 3.
- Ambulatory blood pressure monitoring may lead to early identification of patients with cardiovascular autonomic neuropathy in the primary care setting 3.
- Skin biopsy can be helpful in selected individuals for the diagnosis of disorders affecting small nerve fibers, but should be used with caution and only with clinical-physiological correlation 3.
Autonomic Function Testing
Autonomic function testing is a crucial component of the diagnostic approach for autonomic neuropathy.
- The autonomic reflex screen is a validated tool to assess sympathetic postganglionic sudomotor, cardiovascular sympathetic noradrenergic, and cardiac parasympathetic function 3.
- Quantitative autonomic biomarkers can be used to assess response to treatment 2.
- Autonomic function testing can guide therapeutic decisions and document improvement with treatment 3.
Laboratory Testing
Laboratory testing is an essential part of the diagnostic approach for autonomic neuropathy.
- Initial laboratory evaluation includes fasting glucose or oral glucose tolerance test, thyroid function tests, kidney function tests, vitamin-B12, serum, and urine protein electrophoresis with immunofixation 3.
- Other laboratory tests should be guided by the clinical context 3.
- Laboratory testing can help identify underlying causes of autonomic neuropathy, such as diabetes or amyloidosis 4, 5.