Cynthia missed her treatment and complains of weakness in her legs upon returning. What condition might she be experiencing?

In the context of missed dialysis treatments, hyperkalemia is a relevant condition that can arise. During dialysis, potassium is effectively removed from the bloodstream. If a patient misses a treatment, the potassium levels can rise significantly due to the body's natural processes, particularly if they have a diet high in potassium or have underlying kidney issues where potassium is not adequately cleared from the body.

Weakness in the legs can be a symptom of high potassium levels. This is because elevated potassium can disrupt normal muscle function and affect nerve impulses, leading to muscle weakness or even paralysis in severe cases. The risk of cardiac issues also increases with hyperkalemia, as it affects the heart's electrical activity.

Other choices, such as hypokalemia, fluid overload, and electrolyte imbalance, could also be relevant symptoms of missed treatments, but hyperkalemia directly addresses the specific complaint of leg weakness in the context of missed dialysis. Thus, it is the most fitting condition in this scenario.