👤 By the CinnaRN Clinical Content Team🕐 Updated 2026-08-23🏷️ Physiological Adaptation🔖 Free to read, print, and share
Also known as: low sodium · low Na
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Use this quick-reference guide to spot, treat, and prevent Hyponatremia on the NCLEX. Keep it handy during review and on exam day!
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📒 The 1-minute cheat sheet
⚠️ Causes
SIADH, water excess, CHF
Diuretics, vomiting, diarrhea
Excess hypotonic IV / D5W
🩺 Signs
Confusion, HA, lethargy
Seizures, coma if severe
N/V, muscle cramps, ↓ DTRs
✅ Do
Restrict fluids if dilutional
Hypertonic 3% NaCl → slow, ICU
Seizure precautions, safety
📌 Avoid
Fast correction → demyelination
Daily wts, strict I&O
📚 Hyponatremia — full study notes
The cheat sheet above is your quick recall card. These notes go deeper — what it is, what to do first, what must be reported, and what to teach.
Hyponatremia is a serum sodium below 135 mEq/L. Sodium drives osmolality and water balance, so a low level pulls water into cells — the brain is most vulnerable, making neurologic changes the central concern. Causes include SIADH, excess water intake, diuretics, and GI losses.
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Key points
Understand these first
Neurologic: headache, confusion, lethargy progressing to seizures and coma
GI: nausea, vomiting, abdominal cramping
Muscle weakness and cramps; possible hypotension if volume-depleted
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Nursing priorities
What to do, in order
Restrict fluids when the cause is dilutional/SIADH
Give hypertonic saline (3%) ONLY for severe, symptomatic hyponatremia, slowly
Institute seizure precautions and monitor neuro status closely
New seizures, worsening confusion, or Na⁺ < 120 mEq/L — notify provider now
Do NOT correct sodium too fast (> 8–12 mEq/L in 24 h)
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Labs & values
Numbers to know
Serum sodium 135–145 mEq/L (hyponatremia < 135)
❓ Hyponatremia: NCLEX FAQs
What are the priority nursing interventions for Hyponatremia?
Restrict fluids when the cause is dilutional/SIADH. Give hypertonic saline (3%) ONLY for severe, symptomatic hyponatremia, slowly. Institute seizure precautions and monitor neuro status closely. Correct sodium slowly — rapid correction risks osmotic demyelination.
What are the warning signs of Hyponatremia a nurse must report?
New seizures, worsening confusion, or Na⁺ < 120 mEq/L — notify provider now. Do NOT correct sodium too fast (> 8–12 mEq/L in 24 h).
What do I need to know about Hyponatremia for the NCLEX?
Neurologic: headache, confusion, lethargy progressing to seizures and coma. GI: nausea, vomiting, abdominal cramping. Muscle weakness and cramps; possible hypotension if volume-depleted.
What lab values are associated with Hyponatremia?
Serum sodium 135–145 mEq/L (hyponatremia < 135).
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Quick Tip
Neurologic: headache, confusion, lethargy progressing to seizures and coma.