Fluid & Electrolytes 2025/2026 | Notes, Mnemonics,
& Quizzes | Nursing & Medical Review Guide
Comprehensive Study Resource | Fluid Balance, Electrolyte Imbalances (Na⁺, K⁺, Ca²⁺, Mg²⁺,
Phos⁻), Acid-Base Regulation, IV Fluids, Clinical Manifestations & Interventions |
Expert-Verified | Exam & Clinical Practice Ready
Introduction
This document provides the complete and updated Fluid & Electrolytes Study Guide for the
2025/2026 academic cycle. It includes detailed notes, high-yield mnemonics, and practice
quizzes to strengthen understanding of fluid compartments, electrolyte regulation, acid-base
balance, and common disorders such as dehydration, hyperkalemia, hyponatremia, and
metabolic acidosis/alkalosis. Designed for nursing and medical students, this resource ensures
mastery for exams and clinical decision-making.
Answer Format
All correct answers, key values, and critical signs are highlighted in bold and green.
Mnemonics are simplified for easy recall, and quizzes are provided with detailed explanations to
reinforce core concepts.
Fluid & Electrolytes Notes | Verified 2025/2026 Content | Exam-Aligned | Nursing & Medical
Mastery Resource
Fluid & Electrolytes Study Guide 2025/2026
1. Fluid Compartments
● Total Body Water: 60% of body weight in adults (70% in infants, 50% in elderly).
○ Intracellular Fluid (ICF): 40% of body weight, inside cells.
○ Extracellular Fluid (ECF): 20% of body weight, includes plasma (5%) and
interstitial fluid (15%).
○ Clinical Correlation: Fluid shifts between compartments affect blood pressure
and organ function. Monitor for edema or dehydration.
● Fluid Movement: Governed by osmosis (water movement) and hydrostatic/osmotic
pressures.
○ Example: High sodium in ECF pulls water from ICF, causing cellular
dehydration.
2. Electrolyte Overview
, ● Sodium (Na⁺): Normal range: 135–145 mEq/L. Regulates fluid balance, nerve
function.
● Potassium (K⁺): Normal range: 3.5–5.0 mEq/L. Critical for cardiac and muscle
function.
● Calcium (Ca²⁺): Normal range: 8.5–10.2 mg/dL. Supports bone health, muscle
contraction, clotting.
● Magnesium (Mg²⁺): Normal range: 1.7–2.2 mg/dL. Aids nerve and muscle function.
● Phosphate (Phos⁻): Normal range: 2.5–4.5 mg/dL. Essential for energy metabolism,
bone health.
3. Electrolyte Imbalances
1. Hyponatremia (<135 mEq/L)
○ Causes: Overhydration, SIADH, diuretics.
○ Signs: Confusion, seizures, lethargy.
○ Mnemonic: SALT LOSS (Seizures, Altered mental status, Lethargy, Tremors,
Low sodium, Overhydration, Stupor, Spasms).
○ Interventions: Restrict fluids, administer hypertonic saline (3% NaCl) cautiously
for severe cases.
2. Hypernatremia (>145 mEq/L)
○ Causes: Dehydration, diabetes insipidus, excessive sodium intake.
○ Signs: Thirst, restlessness, coma.
○ Mnemonic: FRIED (Fever, Restlessness, Increased BP, Edema, Dry mucous
membranes).
○ Interventions: Administer hypotonic fluids (e.g., 0.45% NaCl), monitor
neurological status.
3. Hypokalemia (<3.5 mEq/L)
○ Causes: Diuretics, vomiting, diarrhea.
○ Signs: Muscle weakness, arrhythmias, flat T waves on ECG.
○ Mnemonic: A SIC WALT (Alkalosis, Shallow respirations, Irritability,
Confusion, Weakness, Arrhythmias, Lethargy, Thready pulse).
○ Interventions: Administer potassium (IV or oral), monitor ECG and renal
function.
4. Hyperkalemia (>5.0 mEq/L)
○ Causes: Renal failure, ACE inhibitors, potassium-sparing diuretics.
○ Signs: Peaked T waves, bradycardia, muscle cramps.
○ Mnemonic: MURDER (Muscle cramps, Urine abnormalities, Respiratory
distress, Decreased cardiac output, ECG changes, Reflexes hyperactive).
○ Interventions: Administer calcium gluconate, insulin/glucose, sodium
bicarbonate; dialysis if severe.
5. Hypocalcemia (<8.5 mg/dL)
○ Causes: Hypoparathyroidism, vitamin D deficiency, pancreatitis.
○ Signs: Tetany, Chvostek’s/Trousseau’s signs, seizures.
○ Mnemonic: CATS (Convulsions, Arrhythmias, Tetany, Spasms).
○ Interventions: Administer calcium gluconate, correct magnesium if low.
& Quizzes | Nursing & Medical Review Guide
Comprehensive Study Resource | Fluid Balance, Electrolyte Imbalances (Na⁺, K⁺, Ca²⁺, Mg²⁺,
Phos⁻), Acid-Base Regulation, IV Fluids, Clinical Manifestations & Interventions |
Expert-Verified | Exam & Clinical Practice Ready
Introduction
This document provides the complete and updated Fluid & Electrolytes Study Guide for the
2025/2026 academic cycle. It includes detailed notes, high-yield mnemonics, and practice
quizzes to strengthen understanding of fluid compartments, electrolyte regulation, acid-base
balance, and common disorders such as dehydration, hyperkalemia, hyponatremia, and
metabolic acidosis/alkalosis. Designed for nursing and medical students, this resource ensures
mastery for exams and clinical decision-making.
Answer Format
All correct answers, key values, and critical signs are highlighted in bold and green.
Mnemonics are simplified for easy recall, and quizzes are provided with detailed explanations to
reinforce core concepts.
Fluid & Electrolytes Notes | Verified 2025/2026 Content | Exam-Aligned | Nursing & Medical
Mastery Resource
Fluid & Electrolytes Study Guide 2025/2026
1. Fluid Compartments
● Total Body Water: 60% of body weight in adults (70% in infants, 50% in elderly).
○ Intracellular Fluid (ICF): 40% of body weight, inside cells.
○ Extracellular Fluid (ECF): 20% of body weight, includes plasma (5%) and
interstitial fluid (15%).
○ Clinical Correlation: Fluid shifts between compartments affect blood pressure
and organ function. Monitor for edema or dehydration.
● Fluid Movement: Governed by osmosis (water movement) and hydrostatic/osmotic
pressures.
○ Example: High sodium in ECF pulls water from ICF, causing cellular
dehydration.
2. Electrolyte Overview
, ● Sodium (Na⁺): Normal range: 135–145 mEq/L. Regulates fluid balance, nerve
function.
● Potassium (K⁺): Normal range: 3.5–5.0 mEq/L. Critical for cardiac and muscle
function.
● Calcium (Ca²⁺): Normal range: 8.5–10.2 mg/dL. Supports bone health, muscle
contraction, clotting.
● Magnesium (Mg²⁺): Normal range: 1.7–2.2 mg/dL. Aids nerve and muscle function.
● Phosphate (Phos⁻): Normal range: 2.5–4.5 mg/dL. Essential for energy metabolism,
bone health.
3. Electrolyte Imbalances
1. Hyponatremia (<135 mEq/L)
○ Causes: Overhydration, SIADH, diuretics.
○ Signs: Confusion, seizures, lethargy.
○ Mnemonic: SALT LOSS (Seizures, Altered mental status, Lethargy, Tremors,
Low sodium, Overhydration, Stupor, Spasms).
○ Interventions: Restrict fluids, administer hypertonic saline (3% NaCl) cautiously
for severe cases.
2. Hypernatremia (>145 mEq/L)
○ Causes: Dehydration, diabetes insipidus, excessive sodium intake.
○ Signs: Thirst, restlessness, coma.
○ Mnemonic: FRIED (Fever, Restlessness, Increased BP, Edema, Dry mucous
membranes).
○ Interventions: Administer hypotonic fluids (e.g., 0.45% NaCl), monitor
neurological status.
3. Hypokalemia (<3.5 mEq/L)
○ Causes: Diuretics, vomiting, diarrhea.
○ Signs: Muscle weakness, arrhythmias, flat T waves on ECG.
○ Mnemonic: A SIC WALT (Alkalosis, Shallow respirations, Irritability,
Confusion, Weakness, Arrhythmias, Lethargy, Thready pulse).
○ Interventions: Administer potassium (IV or oral), monitor ECG and renal
function.
4. Hyperkalemia (>5.0 mEq/L)
○ Causes: Renal failure, ACE inhibitors, potassium-sparing diuretics.
○ Signs: Peaked T waves, bradycardia, muscle cramps.
○ Mnemonic: MURDER (Muscle cramps, Urine abnormalities, Respiratory
distress, Decreased cardiac output, ECG changes, Reflexes hyperactive).
○ Interventions: Administer calcium gluconate, insulin/glucose, sodium
bicarbonate; dialysis if severe.
5. Hypocalcemia (<8.5 mg/dL)
○ Causes: Hypoparathyroidism, vitamin D deficiency, pancreatitis.
○ Signs: Tetany, Chvostek’s/Trousseau’s signs, seizures.
○ Mnemonic: CATS (Convulsions, Arrhythmias, Tetany, Spasms).
○ Interventions: Administer calcium gluconate, correct magnesium if low.
