familial pseudohyperkalemia
An inherited, mild, non-hemolytic subtype of hereditary stomatocytosis that is associated with a temperature-dependent anomaly in red cell membrane permeability to potassium that leads to high in vitro potassium levels in samples stored below 37°C. FP is not associated with additional hematological abnormalities, although affected individuals may show some mild abnormalities like macrocytosis.