Fluid and electrolytes

It's best to know what is affected MOST by the lytes. They all pretty much affect the whole body but apply the finding clinically. Sodium will usually have neuro effects. If you have a very confused patient, check lytes. Potassium usually effects the heart, but also musculature in general. But if potassium is either low or high, usually you monitor the heart. Calcium mostly effects muscle. Both the heart and skeletal muscle, but generally questions will apply to skeletal muscle, such and twitching and tremors or paresthesia and tetany. And so on for each lyte. Don't identify by ALL symptoms. Learn to identify by the most common symptoms of each imbalance. NCLEX will not be so vague as to expect you to know which lab value is off based off of vomiting and fatigue as symptoms. Instead it may ask you which lab value would you expect to be abnormal when the patient has is nauseous and has a positive trousseau's sign. Trousseau's is for calcium deficiency. Or it may state there is a parathyroid problem and ask what signs and symptoms would be expected. Since parathyroid effects calcium, there would be an answer with very obvious calcium deficiency or excess symptoms.

Oh and also try to focus on what each lyte does in the body, and it should make understanding side effects easier.