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NCLEX-RN · 8 Essential Terms
NCLEX fluid and electrolyte patterns: hypokalemia and hyperkalemia, sodium and calcium imbalances, and fluid volume excess versus deficit. Safety cues for the exam, not replacement protocols.
These are licensure study notes, not orders for patient care. Follow your program, your facility policy, and the current test plan.
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A low serum potassium. The exam picture includes muscle weakness, cramps, ileus, and U waves. Digoxin toxicity is more likely when potassium is low.
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A low serum potassium. The exam picture includes muscle weakness, cramps, ileus, and U waves. Digoxin toxicity is more likely when potassium is low.
Mnemonic. Low K means weak muscles and a U wave. Never give potassium by IV push.
Exam trap. IV-push potassium is a core never event on the exam. Oral or diluted, controlled IV replacement is the safe story. A client on digoxin plus a loop diuretic is the stem to read twice.
A high serum potassium. The urgent picture is a peaked T wave and the risk of a dangerous rhythm. Exam treatments include shifting potassium with insulin and glucose while the heart is monitored.
Mnemonic. High K peaks the T wave. Insulin with glucose is a shift, not a cure by itself.
Exam trap. The trap is treating a peaked T wave as a low-potassium U wave, or giving more potassium because the client takes a diuretic. Confirm the lab and the ECG direction before any replacement.
A low serum sodium. Symptoms range from headache and confusion to seizures. The cause decides the treatment: fluid restriction fits the SIADH story and does not fit every low sodium.
Mnemonic. Low sodium confuses the brain. Restricting water is right only for the cause that is too much water.
Exam trap. The trap is fluid restriction for a client who is dry. Volume status matters. Correcting sodium too fast is the brain-injury stem, so the exam prefers a controlled plan over a bold one.
A high serum sodium, often from water loss. Thirst, dry mucosa, and restlessness are the early picture. Correction is deliberate because rapid sodium shifts injure the brain.
Mnemonic. High sodium means the body is concentrated. Thirst is the early alarm if the client can feel it.
Exam trap. The trap is free water given so fast that the sodium plunges. Older adults may not report thirst, so a dry mouth and confusion do not wait for a complaint.
A low serum calcium. The exam signs are tingling, tetany, a positive Chvostek sign at the cheek, and a positive Trousseau sign with a blood-pressure cuff.
Mnemonic. Low calcium makes nerves irritable: the cheek twitches and the hand spasms.
Exam trap. Thyroid and neck surgery is the classic stem because the parathyroids may have been disturbed. Seizure precautions fit. Do not confuse the peaked T of high potassium with the tetany of low calcium.
A high serum calcium. The memory line is bones, stones, groans, and thrones: bone pain, kidney stones, abdominal groans, and constipation, plus decreased reflexes.
Mnemonic. High calcium slows things down: slow bowels, slow reflexes, stones.
Exam trap. The trap is bed rest. Immobility makes the calcium problem worse. Hydration and ambulation are the classic nursing actions. Thiazides can raise calcium; they are not the diuretic that wastes it.
Too much fluid in the vascular space. The picture is weight gain, edema, bounding pulses, jugular venous distention, and crackles. Dyspnea means sit the client up.
Mnemonic. Excess is wet lungs, a big pulse, and a rising daily weight.
Exam trap. The trap is a client in heart failure who is encouraged to drink more because the mouth is dry from oxygen. Daily weight, not ankle edema alone, is the cleanest trend.
Too little fluid. The picture is acute weight loss, thirst, a fast weak pulse, low blood pressure when severe, oliguria, and poor turgor. Older skin tents even when the client is not dry.
Mnemonic. Deficit is a fast, weak pulse and a weight that fell since yesterday.
Exam trap. The trap is using tenting on an older adult as proof of dehydration. Look at weight, urine, pulse, and mucosa together. The treatment is replacement matched to the cause, not a generic rush of free water.