NCLEX-RN Fluid and Electrolyte Imbalances — Practice Questions

Normal serum potassium is 3.5-5.0 mEq/L (or 3.5-5.0 mmol/L). Potassium is the major intracellular cation and is critical for normal cardiac, neuromuscular, and cellular function. Hypokalemia (below 3.5) causes muscle weakness, cramping, arrhythmias (U waves on ECG, flattened T waves, ST depression), constipation, polyuria. Common causes: diuretics (loop and thiazide), vomiting, diarrhea, inadequate intake, insulin therapy, alkalosis. Hyperkalemia (above 5.0) causes muscle weakness, paresthesias, life-threatening cardiac arrhythmias (peaked T waves, widened QRS, ventricular fibrillation, asystole). Common causes: renal failure, ACE inhibitors/ARBs, potassium-sparing diuretics, rhabdomyolysis, hemolysis, acidosis. NCLEX frequently tests potassium because of its narrow therapeutic range and severe consequences of imbalance.

Normal fasting blood glucose is 70-100 mg/dL (3.9-5.5 mmol/L). Values 100-125 mg/dL indicate prediabetes (impaired fasting glucose); 126 mg/dL or higher on two separate tests indicates diabetes. Hypoglycemia (below 70) causes shakiness, sweating, anxiety, hunger, confusion, and at severe levels (below 40-50) seizures, loss of consciousness, and death. Treatment of hypoglycemia in a conscious client: 15-20 grams of fast-acting carbohydrate (4 oz juice, 3-4 glucose tablets, 1 tbsp honey), then recheck in 15 minutes; repeat if still low; once normal, provide complex carb and protein snack. For unconscious clients: IV dextrose (D50) or IM/SQ glucagon. Hyperglycemia symptoms: polyuria, polydipsia, polyphagia, fatigue, blurred vision. Diabetic ketoacidosis (DKA) is a serious complication of type 1 diabetes with glucose typically over 300, ketones, acidosis.

Warfarin is monitored using PT/INR. Therapeutic INR ranges: 2.0-3.0 for most conditions (atrial fibrillation, DVT, PE, after major heart valve surgery); 2.5-3.5 for mechanical heart valves and recurrent thromboembolism. INR above 3.0-3.5 (depending on indication) increases bleeding risk; below the therapeutic range provides inadequate anticoagulation. PTT (or aPTT) monitors heparin and is targeted at 1.5-2.5 times the control. Antidotes: vitamin K reverses warfarin (slowly, hours to days); protamine sulfate reverses heparin (rapidly). Warfarin teaching: consistent intake of vitamin K-containing foods (green leafy vegetables — eat consistent amounts rather than avoiding); avoid alcohol; report unusual bleeding (gums, urine, stool); many drug interactions (especially antibiotics, NSAIDs, amiodarone) — coordinate all medications with prescriber. Direct oral anticoagulants (DOACs like apixaban, rivaroxaban) don't require routine INR monitoring.

Digoxin is a cardiac glycoside used for atrial fibrillation and heart failure. It slows heart rate (negative chronotropy) and increases contractility (positive inotropy). The nurse counts the apical heart rate for a FULL minute before administration. Hold and notify the provider if apical HR is below 60 bpm in adults (below 70 in children, below 90 in infants). Digoxin has a narrow therapeutic range (therapeutic level 0.5-2.0 ng/mL); toxicity occurs at higher levels. Signs of digoxin toxicity: anorexia, nausea, vomiting, visual disturbances (yellow-green halos around lights, blurred vision), arrhythmias including bradycardia, confusion, fatigue. Hypokalemia increases digoxin toxicity risk — monitor potassium especially in clients also taking diuretics. Antidote: digoxin immune Fab (Digibind). NCLEX commonly tests both the pre-administration check and toxicity symptoms.

The 'Rule of 15' is the standard treatment for hypoglycemia in a conscious, swallowing client: (1) Give 15 grams of fast-acting carbohydrate — options include 4 oz fruit juice, 4 oz regular (not diet) soda, 1 tbsp honey or sugar, 3-4 glucose tablets, 8 oz milk; (2) Wait 15 minutes; (3) Recheck blood glucose; (4) If still below 70 mg/dL, repeat the 15 grams of carbohydrate; (5) Once normal, give a snack with complex carbohydrate and protein to prevent recurrence (e.g., crackers with cheese, half a sandwich) if the next meal is more than an hour away. For unconscious clients: never give anything by mouth; administer IM/SQ glucagon (1 mg) if available, IV dextrose (D50) if access available, or call EMS. Common causes of hypoglycemia: too much insulin or oral hypoglycemic, missed meal, increased exercise, alcohol.

Type 1 diabetes (formerly juvenile/insulin-dependent diabetes): autoimmune destruction of pancreatic beta cells leads to absolute insulin deficiency. Onset usually in childhood/young adulthood but can occur at any age. Always requires insulin therapy. About 5-10% of diabetes cases. Higher risk of DKA. Symptoms typically develop quickly. Type 2 diabetes (formerly adult-onset/non-insulin-dependent): insulin resistance plus relative insulin deficiency. Onset typically in adulthood, but increasingly seen in younger people due to obesity. Strong association with obesity, sedentary lifestyle, family history. About 90-95% of diabetes cases. May be managed initially with diet, exercise, and oral medications (metformin first-line); often progresses to require insulin over years. Higher risk of HHS (hyperosmolar hyperglycemic state) than DKA. Symptoms often develop gradually. Both types have similar long-term complications: retinopathy, nephropathy, neuropathy, cardiovascular disease.

ST-elevation myocardial infarction (STEMI) is a medical emergency where coronary occlusion is causing actively-progressing myocardial damage. 'Time is muscle' — delays in reperfusion increase infarct size and worsen outcomes. Standard initial management (often remembered as MONA-BASH or similar mnemonics, though MONA is no longer routine): (1) Oxygen if SpO2 below 90% (no longer routine for everyone — supplemental O2 may worsen outcomes in non-hypoxic patients); (2) Aspirin 325 mg chewed (decreases platelet aggregation, reduces mortality); (3) Nitroglycerin sublingual (vasodilation, reduces preload and afterload, relieves ischemia — contraindicated in inferior MI with right ventricular involvement, sildenafil use in 24 hrs, severe hypotension); (4) Morphine for pain not relieved by nitrates (use cautiously); (5) IV access and continuous monitoring; (6) Reperfusion: PCI (percutaneous coronary intervention) within 90 minutes from first medical contact is gold standard; thrombolytics if PCI unavailable within timeframe. Other meds: beta-blocker, statin, ACE inhibitor.

Women, elderly clients, and people with diabetes may present with atypical MI symptoms that delay diagnosis. Classic 'textbook' MI: crushing substernal chest pain radiating to left arm or jaw, diaphoresis, nausea, sense of impending doom. Atypical presentations more common in women, elderly, diabetic clients: unusual fatigue (often weeks before the event); shortness of breath as the primary or only symptom; indigestion or epigastric pain often mistaken for GI issues; nausea and vomiting; back, jaw, or neck pain; lightheadedness or syncope; pain in shoulders or arms; sleep disturbances. Women frequently delay seeking care because their symptoms are dismissed or attributed to anxiety. Nurses must maintain high index of suspicion for cardiac etiology when women, elderly, or diabetic clients present with vague or atypical symptoms. Diabetes can blunt typical pain because of neuropathy — silent MI is common in diabetic clients.

Pressure injury staging (NPIAP): Stage 1 — intact skin with non-blanchable redness; Stage 2 — partial-thickness skin loss with exposed dermis (looks like a shallow open ulcer, blister, or abrasion); Stage 3 — full-thickness skin loss exposing subcutaneous fat; Stage 4 — full-thickness with exposed bone, tendon, or muscle; Unstageable — full-thickness with eschar or slough obscuring depth; Deep Tissue Injury — intact or non-intact skin with persistent purple/maroon discoloration. Management principles for Stage 2: clean the wound (saline or commercial wound cleanser, not hydrogen peroxide which is cytotoxic); choose appropriate dressing (hydrocolloid for moist wound healing in clean wounds, foam for absorption, transparent film for shallow wounds); reposition every 2 hours; use pressure-redistribution surfaces (alternating pressure mattresses); manage moisture (incontinence care); optimize nutrition (protein, vitamin C, zinc); avoid friction and shear. Never massage pressure injuries — causes more tissue damage.

Respiratory depression is the most serious adverse effect of opioids. A respiratory rate below 12 in adults warrants attention; below 10 is concerning; below 8 is critical. Priority actions: (1) Hold further opioid doses; (2) Stimulate the client (call name, gentle shake) and encourage deep breathing; (3) Assess oxygen saturation, level of consciousness, pupil size (opioids cause miosis), other vital signs; (4) Reposition for airway patency; (5) Have naloxone (Narcan) ready and administer if criteria met: 0.04-0.1 mg IV titrated to effect (full dose 0.4-2 mg if severe); (6) Provide oxygen and ventilation support as needed; (7) Notify provider. Naloxone administration: titrate to restore adequate respirations without precipitating withdrawal pain. Naloxone has a shorter half-life than most opioids, so repeat doses or infusion may be needed. After naloxone, the client may experience severe pain (the reason for the original opioid) — manage with non-opioid alternatives initially and resume opioids cautiously once safe.