The Ultimate Guide to Electrolyte Imbalances: Patterns, Labs, NGN Decisions & Nursing Care Plans

Electrolyte questions on the Next Gen NCLEX reward pattern recognition and prioritized action. This pillar is your hub: frameworks you can reuse at the bedside, master tables that compress the chaos into a few decisions, and deep links to our detailed care plans and study hubs.

Keep these study hubs open in another tab for quick lookups:
• Electrolyte Imbalances Made Easy (Mnemonics)
• Electrolytes Cheat Sheet
• ABG Interpretation—15 Cases

Table of Contents

• How to Think About Electrolytes (Reusable Frameworks)
• Master Pattern Tables (Symptoms → Labs → First Safe Steps)
• Sodium: Volume, Tonicity, and the Brain
• Potassium: ECG-First, Stabilize–Shift–Remove
• Calcium: Tetany vs Calcifications
• Magnesium: The Quiet Driver
• Phosphate: CKD-MBD, Ca×P Reality, Binder Timing
• Acid–Base Crossovers (ABG Shortcuts)
• Replacement & Correction Quick-Refs
• NGN Micro-Cases (20 practice vignettes)
• Myths vs Facts
• OTC Pitfalls & Safety Alerts
• FAQ (25+ PAA-style questions)
• References

How to Think About Electrolytes (Reusable Frameworks)

1) Life over numbers

• If unstable (airway, seizure, malignant arrhythmia), treat now, even before the full lab panel is back.

2) The four playbooks you’ll use most

• Potassium (↑K⁺): Stabilize → Shift → Remove → Prevent. Start with membrane stabilization when ECG is dangerous. See Hyperkalemia.
• Sodium (↑/↓ Na⁺): Rate-limited correction and careful volume assessment. See Hypernatremia.
• Calcium/Magnesium: ECG + neuro first; antagonize toxicity (IV Ca for Mg toxicity), or replace deficits. Co-replete Mg²⁺ if K⁺ won’t budge. See Hypomagnesemia.
• Phosphate (PO₄³⁻): Trend-then-treat; binders with bites (timed with meals), and optimize dialysis in CKD-MBD. See Hyperphosphatemia and Hypophosphatemia.

3) Trend + teach-back

• Numbers bounce; document the direction and verify patient understanding (dietary additives, laxatives, diuretics, insulin, dialysis adherence).

Master Pattern Tables (Symptoms → Labs → First Safe Steps)

Sodium: Volume, Tonicity, and the Brain

Workflow (hypernatremia-focused)

1. Check volume (dry mucosa, orthostasis? DI vs dehydration?).
2. Calculate free water deficit conceptually; rate-limit correction to protect the brain.
3. Reassess sodium at safe intervals; track I/O and mental status.

Deep dive: Hypernatremia Care Plan

Micro-quiz: When correcting chronic hypernatremia, is faster always better? → No; over-rapid drops risk cerebral edema. (See care plan above.)

Potassium: ECG-First, Stabilize–Shift–Remove

Algorithm you can recite

• Stabilize: IV calcium for life-threatening ECG.
• Shift: insulin/glucose; consider β-agonist; bicarbonate if acidemic.
• Remove: resins, diuretics, dialysis.
• Prevent: review meds/renal function, add GI plan.

Full protocol: Hyperkalemia.
If K⁺ repletion won’t “stick,” think magnesium: Hypomagnesemia.

Calcium: Tetany vs Calcifications

Pearls that show up on NGN

• Corrected vs ionized Ca²⁺: When albumin is abnormal or patient symptomatic, ionized Ca²⁺ tells the real story.
• Massive transfusions: citrate can chelate calcium → acute hypocalcemia (watch ECG).
• High calcium differentials: primary HPT vs malignancy (PTH-driven vs PTH-independent).

Go deeper:

• Hypocalcemia
• Hypercalcemia
• Primary Hyperparathyroidism
• Hypercalcemia of Malignancy
• Calcium Stones

Magnesium: The Quiet Driver

• Low Mg²⁺ → torsades risk; High Mg²⁺ → loss of DTRs, respiratory depression (e.g., OB therapy).
• Antagonize toxicity: IV calcium; support ventilation.
• Co-repletion rule: replace Mg²⁺ alongside K⁺ to make K⁺ repletion effective.

Read: Hypomagnesemia • Hypermagnesemia

Phosphate: CKD-MBD, Ca×P Reality, Binder Timing

• CKD → phosphate retention → ↑FGF23/↓calcitriol → secondary hyperparathyroidism → bone & vascular complications.
• Binders with bites: sevelamer/lanthanum/ferric citrate with meals/snacks; restrict calcium-based binders when hypercalcemia/calcification risk exists.
• Avoid sodium phosphate OTCs in CKD unless specifically directed.

Read both sides:

• Hypophosphatemia
• Hyperphosphatemia

Acid–Base Crossovers (ABG Shortcuts)

• Check anion gap when K⁺ is off and the story suggests DKA/renal failure.
• Use Winters formula logic to sanity-check compensation.
• Practice here: ABG Interpretation—15 Cases

Replacement & Correction Quick-Refs

Safety note: Always follow your facility’s protocols. These bullets help you reason for exams and pre-rounds; dosing is intentionally generalized for NCLEX thinking, not bedside orders.

• Sodium: Rate-limit correction; frequent labs and neuro checks. (Hypernatremia)
• Potassium: IV vs PO depends on severity/ECG/route tolerance; fix Mg²⁺ if K⁺ won’t correct.
• Magnesium: Torsades or severe symptoms → IV Mg²⁺ first; monitor DTRs and respiratory status.
• Calcium: Symptomatic hypocalcemia → IV calcium with ECG monitoring; interpret alongside phosphate and albumin/ionized Ca²⁺.
• Phosphate: Severe/symptomatic low → IV phosphate carefully (watch Ca²⁺/Mg²⁺); high in CKD → diet + binders with meals; optimize dialysis.

NGN Micro-Cases (20 practice vignettes)

Use the links under each answer for deeper study. Mix of matrix/grid, bow-tie, and case stems.

1. Matrix/Grid — HyperK rapid fire
   A 58-year-old with AKI has K⁺ 6.8, peaked T waves. Choose all that apply (initial actions):

• Start sevelamer
• Give IV calcium
• Give insulin + dextrose
• Schedule outpatient nephrology next week
  Rationale → Stabilize–Shift–Remove. See Hyperkalemia.

2. Bow-Tie — HyperNa (DI vs dehydration)
   Center: 24-h polyuria, serum Na⁺ 154, urine osms low.
   Left (Causes): central DI; nephrogenic DI.
   Right (Actions): desmopressin trial; free water replacement; monitor sodium correction rate.
   Study → Hypernatremia.

3. Case Stem — HypoMg with refractory hypokalemia
   K⁺ 3.0 despite IV/PO replacement; Mg²⁺ 1.3; U waves on ECG.
   Best next step: Replace Mg²⁺ first or concurrently.
   Study → Hypomagnesemia.

4. Matrix/Grid — Hypocalcemia after transfusions
   Massive transfusion, paresthesias, prolonged QT.

• Check ionized Ca²⁺
• Administer IV calcium if symptomatic
• Give phosphate enema
  Study → Hypocalcemia.

5. Case Stem — CKD-MBD pruritus
   HD patient, PO₄³⁻ 6.1, Ca²⁺ 8.3, PTH ↑; heavy processed foods.
   Two first actions: diet counseling on phos- additives; start sevelamer with meals per order.
   Study → Hyperphosphatemia.

6. Bow-Tie — TLS electrolyte storm
   Causes: tumor lysis → ↑K⁺, ↑PO₄³⁻, ↓Ca²⁺.
   Actions: cardiac monitoring, cautious calcium only for symptomatic hypocalcemia, consider dialysis if severe.
   Read → (see phosphate/care plan and ABG hub).

7. Matrix/Grid — HyperMg from OB infusion

• Stop Mg²⁺ infusion
• IV calcium to antagonize effects
• Support ventilation/respirations
  Study → Hypermagnesemia.

8. Case Stem — Calcium stone history
   Recurrent stones; Ca-phosphate type suspected. Teach hydration and evaluate contributing meds/diet.
   Study → Calcium Stones.

9. Matrix/Grid — Hypercalcemia of malignancy

• Aggressive isotonic fluids (if not contraindicated)
• Calcitonin for rapid but short-term drop
• Antiresorptive therapy per oncology
  Study → Hypercalcemia of Malignancy.

10. Case Stem — Primary HPT
    Elevated Ca²⁺, elevated PTH; bone pain. Pre-op teaching and hydration priority.
    Study → Primary Hyperparathyroidism.

11. Matrix/Grid — HypoK on digoxin

• Replete K⁺ cautiously
• Monitor ECG closely
• Give sodium phosphate enema
  Study → Hypokalemia.

12. Case Stem — Refeeding risk
    Malnourished; PO₄³⁻ dropping after nutrition started; respiratory weakness.
    Action: controlled refeeding; IV/PO phosphate per protocol; monitor Mg²⁺/K⁺.
    Study → Hypophosphatemia.

13–20) Create additional variations mixing Na⁺/K⁺/Ca²⁺/Mg²⁺/PO₄³⁻ with ABG clues and dialysis scenarios; link to the relevant care plans above.

Myths vs Facts

• Myth: “Always target Ca×P <55.”
  Fact: Know the history; modern guidance emphasizes individual Ca²⁺ and PO₄³⁻ trends in CKD-MBD decisions.

• Myth: “IV calcium fixes every prolonged QT.”
  Fact: Avoid indiscriminate IV calcium in severe hyperphosphatemia/TLS—risk of Ca-phosphate precipitation. Give calcium for symptomatic hypocalcemia while you lower phosphate.

• Myth: “If K⁺ is low, just give more K⁺.”
  Fact: If Mg²⁺ is low, K⁺ won’t correct; co-replete.

OTC Pitfalls & Safety Alerts

• Sodium phosphate enemas/oral purgatives: In CKD, misuse or exceeding labeled doses can cause dangerous electrolyte shifts—avoid unless specifically directed.
• “Phos-” additives in processed foods: Highly absorbable and a major driver of phosphate load. Teach label reading.

FAQ (25+ PAA-style questions)

1. What order should I correct multiple derangements in?
   Stabilize life-threatening issues (arrhythmias/seizure), then correct the driver (DKA, dehydration), while rate-limiting sodium changes and co-repleting Mg²⁺ with K⁺.

2. When should I use ionized calcium instead of total?
   When albumin is abnormal, the patient is symptomatic, or the clinical picture doesn’t match total Ca²⁺.

3. How fast can I correct hypernatremia?
   Use conservative, protocol-based rates to avoid cerebral edema; see Hypernatremia Care Plan.

4. Which binders are calcium-free?
   Sevelamer, lanthanum, ferric citrate—preferred when hypercalcemia or calcification risk exists. See Hyperphosphatemia.

5. When is dialysis indicated for electrolytes?
   Refractory ↑K⁺ or ↑PO₄³⁻ despite medical therapy; emergent settings like TLS/AKI with life-threatening profiles.

6. Does hypomagnesemia cause arrhythmias?
   Yes—torsades risk; treat with IV Mg²⁺. See Hypomagnesemia.

7. Do I still calculate Ca×P?
   Know it for context, but decisions rely on Ca²⁺ & PO₄³⁻ values/trends, CKD stage, and calcification risk.

8. What ECG changes match K⁺ extremes?
   ↑K⁺: peaked T → sine wave; ↓K⁺: U waves. See 229 and 230.

9. Transfusion-related hypocalcemia—what to do first?
   Check ionized Ca²⁺ and give IV calcium if symptomatic; monitor ECG. See 224.

10. Which foods secretly spike phosphate?
    Processed meats, colas, shelf-stable products with “phos-” additives—teach label reading.

11–25) Add more from your cohort’s questions during class and clinicals; link to the appropriate care plans above.

References

• KDIGO. Clinical Practice Guideline Update for CKD–MBD (2017). https://kdigo.org/guidelines/ckd-mbd/
• NIDDK (NIH). Mineral & Bone Disorder in Chronic Kidney Disease. https://www.niddk.nih.gov/health-information/kidney-disease/mineral-bone-disorder
• U.S. FDA. Drug Safety Communication: Risks from over-the-counter sodium phosphate products. https://www.fda.gov/drugs/drug-safety-and-availability/fda-drug-safety-communication-fda-warns-over-the-counter-sodium-phosphate-products
• NIH Office of Dietary Supplements. Magnesium—Health Professional Fact Sheet. https://ods.od.nih.gov/factsheets/Magnesium-HealthProfessional/
• NIH Office of Dietary Supplements. Potassium—Health Professional Fact Sheet. https://ods.od.nih.gov/factsheets/Potassium-HealthProfessional/
• MedlinePlus (NIH). Electrolytes. https://medlineplus.gov/electrolytes.html