Dialysis disequilibrium syndrome and other treatment complications of extreme uremia: a rare occurrence yet not vanished.

Severe uremia is now a rare occurrence in most developed nations, and yet is still present in many countries of the world. It includes clinical manifestations such as calciphylaxis and uremic frost, which are now rarely seen. Patients with extremely high levels of blood urea nitrogen (above 175 mg/dL) are at a higher risk of experiencing first-time hemodialysis-related complications, in particular dialysis disequilibrium syndrome (DDS). DDS is a central nervous disorder characterized by a wide variety of neurological symptoms that range from nausea and vomiting to even death due to cerebral edema. There are 2 main theories to explain its pathophysiology: the reverse urea effect, which considers that the shift of urea between brain intracellular space and plasma is not immediate, causing a higher concentration of urea within the brain and leading to cerebral edema. The second theory considers that after hemodialysis, patients have transient paradoxical metabolic acidosis within the central nervous system, displacing Na(+) and K(+) from organic anions, making them osmotically active and again leading to cerebral edema. The main goal is to prevent the occurrence of DDS, for which there are several proposed measures including continuous renal replacement therapies. Once established, treatment should be focused on supportive therapy. Another uncommon phenomenon described in patients who initiate hemodialysis is transient pulmonary leukocyte margination, which in conjunction with an inflammatory milieu, may lead to non-cardiogenic pulmonary edema. We present the case of a young adult with severe uremia who, despite application of recommended measures, developed DDS and non-cardiogenic pulmonary edema.