eMedicine Specialties > Nephrology > Chronic Kidney Disease
Encephalopathy, Uremic: Differential Diagnoses & Workup
Updated: Oct 29, 2009
- Overview
- Differential Diagnoses & Workup
- Treatment & Medication
- Follow-up
Differential Diagnoses
Other Problems to Be Considered
Drug intoxication
Cerebrovascular accident
Encephalopathy from drugs normally excreted or metabolized by the kidney (ie, meperidine, cimetidine)
Workup
Laboratory Studies
- Electrolytes, BUN, creatinine, and glucose10
- Markedly elevated BUN and creatinine levels are seen in uremic encephalopathy.
- Obtain serum electrolyte and glucose measurements to rule out hyponatremia, hypernatremia, hyperglycemia, and hyperosmolar syndromes as the cause of encephalopathy.
- Obtain a complete blood cell count to detect leukocytosis, which may suggest an infectious cause and determine whether anemia is present. (Anemia may contribute to the severity of mental alterations.)
- Obtain serum calcium, phosphate, and PTH levels to determine the presence of hypercalcemia, hypophosphatemia, and severe hyperparathyroidism, which cause metabolic encephalopathy.
- Serum magnesium levels may be elevated in a patient with renal insufficiency, particularly if the patient is ingesting magnesium-containing antacids. Hypermagnesemia may manifest as encephalopathy.
- Order a toxicology screen in all patients.
- Medication levels
- Determine drug levels because medications may accumulate in patients with kidney failure and contribute to encephalopathy (eg, digoxin, lithium).
- Some medications cannot be detected and are excreted by the kidney. These may also accumulate in patients with kidney failure, resulting in encephalopathy (eg, penicillin, cimetidine, meperidine, baclofen).
Imaging Studies
- Severe symptoms
- Obtain an MRI or head CT scan for a uremic patient who presents with severe neurologic symptoms to rule out structural abnormalities (eg, cerebrovascular accident, intracranial mass).
- A CT scan does not demonstrate any characteristic findings for uremic encephalopathy.
- With milder symptoms, initially treat the patient with dialysis and observe for neurologic improvement.
Other Tests
- Electroencephalogram
- An EEG is commonly performed on patients with metabolic encephalopathy. Findings typically include the following: (1) slowing and loss of alpha frequency waves, (2) disorganization, and (3) intermittent bursts of theta and delta waves with slow background activity.
- Reduction in frequency of EEG waves correlates with the decrease in renal function and the alterations in cerebral function. After the initial period of dialysis, clinical stabilization may occur while the EEG findings do not improve. Eventually, EEG results move toward normal.
- Aside from the routine EEG, evoked potentials (EPs) (ie, EEG signals that occur at a reproducible time after the brain receives a sensory stimulus [eg, visual, auditory, somatosensory]) may be helpful in evaluating uremic encephalopathy.
- Chronic renal failure prolongs latency of the cortical visual-evoked response. Auditory-evoked responses are generally not altered in uremia, but delays in the cortical potential of the somatosensory-evoked response do occur.
- Cognitive function tests: Several cognitive function tests are used to evaluate uremic encephalopathy.
- Uremia may result in worse performance on the trail-making test, which measures psychomotor speed; the continuous memory test, which measures short-term recognition; and the choice reaction time test, which measures simple decision making.
- Alterations in choice reaction time appear to correlate best with renal failure.
Procedures
- Lumbar puncture
- Lumbar puncture is not routinely performed; however, it may be indicated to find other causes of encephalopathy if a patient's mental status does not improve after initiation of dialysis.
- No specific CSF finding indicates uremic encephalopathy.
More on Encephalopathy, Uremic |
| Overview: Encephalopathy, Uremic |
 Differential Diagnoses & Workup: Encephalopathy, Uremic |
| Treatment & Medication: Encephalopathy, Uremic |
| Follow-up: Encephalopathy, Uremic |
| References |
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References
Bolton CF, Young GB. Encephalopathy of chronic renal failure. In: Neurological Complications of Renal Disease. 1990:49-74.
Brouns R, De Deyn PP. Neurological complications in renal failure: a review. Clin Neurol Neurosurg. Dec 2004;107(1):1-16. [Medline].
Arieff AI. Nervous system manifestations of renal failure. In: Schrier RW, ed. Diseases of the Kidney. Lippincott; 2007:2460-2482.
Biasioli S, D'Andrea G, Feriani M, Chiaramonte S, Fabris A, Ronco C, et al. Uremic encephalopathy: an updating. Clin Nephrol. Feb 1986;25(2):57-63. [Medline].
Biasioli S. Neurologic aspects of dialysis. In: Nissenson A, Fine R, eds. Clinical Dialysis. 2005:855-876.
Moe SM, Sprague SM. Uremic encephalopathy. Clin Nephrol. Oct 1994;42(4):251-6. [Medline].
Deguchi T, Isozaki K, Yousuke K, Terasaki T, Otagiri M. Involvement of organic anion transporters in the efflux of uremic toxins across the blood-brain barrier. J Neurochem. Feb 2006;96(4):1051-9. [Medline].
De Deyn PP, Vanholder R, Eloot S, et al. Guanidino compounds as uremic (neuro)toxins. Semin Dial. Jul-Aug 2009;22(4):340-5. [Medline].
Liu M, Liang Y, Chigurupati S, Lathia JD, Pletnikov M, Sun Z, et al. Acute kidney injury leads to inflammation and functional changes in the brain. J Am Soc Nephrol. Jul 2008;19(7):1360-70. [Medline].
Yamamoto T, Satomura K, Okada S, et al. Risk factors for neurological complications in complete hemolytic uremic syndrome caused by Escherichia coli O157. Pediatr Int. Apr 2009;51(2):216-9. [Medline].
Further Reading
Keywords
uremic encephalopathy, encephalopathy, uremia, encephalopathies, metabolic encephalopathy, treatment encephalopathy, uremic syndrome
