Abstract Background and Aims To illustrate the phenomenon of alternating true hyperkalemia and pseudohyperkalemia in adult sickle cell disease. Method Case Report Results Sickle cell disease (SCD) predisposes the patient to recurrent episodes of acute painful hemolytic crisis. Sickle cell nephropathy (SCN) is not uncommon in adult patients. The presence of sickled erythrocytes in the renal medullary vessels is the hallmark of the disease and renal manifestations include renal ischemia, microinfarcts, renal papillary necrosis and renal tubular abnormalities with variable clinical presentations. Furthermore, acute hemolytic crisis can be complicated by sepsis. Hemolysis, specifically, intravascular hemolysis, can produce hyperkalemia. Additionally, reduced glomerular filtration rate from SCN predisposes to hyperkalemia. Pseudo-hyperkalemia was first reported by Hartmann and Mellinkoff in 1955 as a marked elevation of serum potassium levels in the absence of clinical evidence of electrolyte imbalance. In pseudohyperkalmia, simultaneously estimated serum potassium exceeds plasma potassium by >0.4 mmol/L. This is often associated with moderate to severe thrombocytosis or leukocytosis. Clearly, hyperkalemia is a potentially lethal condition. At the same time, the institution of inappropriate treatment of pseudo-hyperkalemia leading to hypokalemia is also equally potentially lethal. We describe a 40-yo African American male patient with sickle cell anemia who exhibited alternating episodes of hyperkalemia and pseudo-hyperkalemia, during consecutive hospital admissions. Pseudohyperkalemia was associated with severe thrombocytosis complicating sepsis. EKG was normal despite measured serum potassium of 6.7 mmol/L (Figure). Conclusion We believe that this is the first report of adult SCD demonstrating alternating cycles of true hyperkalemia and pseudo-hyperkalemia at different times. We must draw attention to the new availability of the new potassium binders, Patiromer and sodium zirconium cyclosilicate. We would advocate for caution in the use of these potent potassium binders and to always give consideration to the presence of pseudo-hyperkalemia under appropriate clinical scenarios. We posit that providers managing adult patients with sickle cell disease must be aware of such a phenomenon to avoid the dangers of overtreatment of episodes of pseudo-hyperkalemia in such patients.