C49-34 All Bound up and Peed Out- Using Albumin to Resolve Methylene Blue Toxicity, a Case Study

Abstract Introduction A 69-year-old woman presented with vasoplegic shock from metformin toxicity treated with methylene blue. Due to methylene blue toxicity, albumin and diuresis was administered with improvement. Case A 69-year-old woman with type 2 diabetes mellitus presented with encephalopathy. She was found to have profound lactic acidosis from metformin toxicity in the setting of acute renal failure from a urinary tract infection. She was intubated and admitted to the intensive care unit with vasopressor and continuous renal replacement therapy. Despite initial management, serial blood gases showed increasing lactate levels. CT angiogram of the abdomen and pelvis and neurological evaluation for underlying stroke or seizure was unrevealing. Methylene blue was added as a rescue medication for vasoplegic shock with improvement. However, the patient had worsened encephalopathy, roving eye movements, persistent fevers, increasing creatinine, and hemolytic anemia. Intravenous albumin and diuresis was given with mild improvement in encephalopathy. The patient required tracheostomy due to prolonged mechanical ventilation and was discharged to post-acute rehab services. Discussion Metformin toxicity is rare but life threatening. Methylene blue has been used as an adjunctive treatment in vasoplegic shock from metformin toxicity (1, 2, 3). However, methylene blue has known side effects, including neurologic dysfunction (4, 5). Serum methylene blue exists in bound and unbound forms. Unbound methylene blue is pharmacologically active in treating vasoplegic shock through mediation of the nitric oxide-guanyl cyclase pathway (6). Unbound methylene blue is renally cleared, but cannot be removed by continuous renal replacement therapy (7). The majority of serum methylene blue exists in a bound state due to high protein affinity, particularly to albumin. Bound methylene blue is pharmacologically inactive and is unable to be renally excreted (4). In this case, we present a novel double approach to management of methylene blue toxicity. By administering albumin, we decreased levels of unbound methylene blue into a pharmacologically inactive state. With diuresis, we encouraged clearance of unbound methylene blue through renal excretion. This approach was associated with improved mental status. Our case highlights a novel off-label use of albumin and diuresis as a potential reversal therapy for methylene blue, which has not been cited previously. This abstract is funded by: None