Uremic encephalopathy: Clinical sciences

Uremic encephalopathy is a metabolic disorder characterized by progressive neurological dysfunction. Now, this typically occurs in the setting of acute kidney injury or AKI, progression of chronic kidney disease or CKD, or under dialysis.

Normally, the kidneys are in charge of cleaning our bodies by excreting toxins like urea into the urine. If our kidneys don’t function properly, these toxins can accumulate in the blood and eventually in the central nervous system, leading to progressive dysfunction, which can present with a wide range of neurologic symptoms, ranging from mild confusion and altered mental status to even coma.

Now, if your patient presents with a chief concern suggesting uremic encephalopathy, you should first perform an ABCDE assessment to determine if they are unstable or stable. Patients with uremic encephalopathy generally present as unstable, so immediately begin acute management! Stabilize the airway, breathing, and circulation. This means you might need to intubate the patient. Next, obtain IV access, and if your patient does not already have dialysis access, you’ll need to emergently place a dialysis catheter as well. Also, don’t forget to put your patient on continuous vital sign monitoring including heart rate, blood pressure, and pulse oximetry, as well as cardiac telemetry. Finally, if needed, provide supplemental oxygen.

Okay, now that you’ve stabilized your patient, let’s look at your next step.

Start with obtaining a focused history and physical examination. You should also order labs like CMP and ABG, as well as a 12-lead ECG, and a chest X-ray.

The history will typically reveal mental status changes like confusion and lethargy, as well as other symptoms of uremia, such as muscle cramps and itching. Additionally, the physical exam may reveal disorientation, impaired attention, and even hallucinations, but also tremor and asterixis. In extreme cases, your patient might experience seizures or even a coma.

On the flip side, labs will typically show elevated blood urea nitrogen or BUN, and creatinine, and may also reveal electrolyte imbalance including hyperkalemia, and an acid-base disorder, most commonly metabolic acidosis. Keep in mind that these lab findings can also be seen in individuals with kidney failure without uremic encephalopathy!

Next, ECG findings typically correlate with the degree of hyperkalemia. The earliest change you’ll see is tall-peaked T waves, followed by P wave flattening, and prolongation of the PR interval. In severe cases, you might even see the disappearance of P waves, the widening of the QRS complex, and the eventual development of a sine-wave appearance.

Finally, the chest x-ray might reveal pulmonary edema, which typically occurs as a result of fluid overload.

At this point you can diagnose uremic encephalopathy! But, keep in mind that you should always rule out other conditions that can cause mental status changes, such as sepsis, metabolic disorders, as well as intoxication or withdrawal.