Body Fluid Compartments Mnemonics

Question 1

What is the ‘60-40-20 Rule’ regarding body fluid distribution?

Answer 1

Total body water = 60% body weight, 40% intracellular fluid (ICF), 20% extracellular fluid (ECF)

Remember: ‘60% total, split 2:1 (ICF:ECF)’

Question 2

What are the subdivisions of extracellular fluid (ECF) represented by the mnemonic PITS?

Answer 2

• Plasma
• Interstitial fluid
• Transcellular fluid
• Solid tissues (bone/connective tissue)

Question 3

What does ‘Na-GLUe’ stand for in the context of effective osmolality?

Answer 3

• Na+ (×2)
• GLUcose (/18)
• Urea excluded (ineffective)

‘Glue holds Na+ and glucose together’

Question 4

What is the normal plasma osmolality range?

Answer 4

280-295 mOsm/kg

Question 5

What does FENa indicate in urine electrolyte interpretation?

Answer 5

• <1%: Pre-renal (e.g., dehydration)
• 1-2%: Gray zone
• > 2%: ATN/diuretics
• <0.1%: Hepatorenal syndrome

Question 6

What does the mnemonic CLUED help interpret in cases of acidosis?

Answer 6

• Cl- > (Na+ + K+) → Low NH4+ → Usually RTA
• Extra Cl- → Diarrhea (negative UAG)

Question 7

What are the isotonic fluids represented by the mnemonic SALINE?

Answer 7

• Saline (0.9%)
• Albumin (5%)
• Lactated Ringer’s
• Isotonic crystalloids
• Normosol/Plasma-Lyte
• Extra (D5NS)

Question 8

What conditions should D5W be avoided in according to the mnemonic SHINE?

Answer 8

• SIADH
• Hyponatremia
• Increased ICP
• Neonates
• Edema states (CHF, cirrhosis)

Question 9

What mechanisms cause edema in CHF, Nephrotic syndrome, and Cirrhosis represented by the mnemonic V-P-S?

Answer 9

• CHF → Venous congestion (↑hydrostatic pressure)
• Nephrotic → Protein leak (↓oncotic pressure)
• Cirrhosis → Splanchnic vasodilation (↓EABV)

Question 10

What is the Na/K Pump’s activity represented by the 3:2:1 Rule?

Answer 10

• Pumps 3 Na+ out
• 2 K+ in
• Uses 1 ATP

Question 11

How do you convert Ca2+ from mg/dL to mmol/L using the ÷4 Rule?

Answer 11

1 mg/dL Ca = 0.25 mmol/L

‘Divide by 4 to convert mg→mmol’

Question 12

What are the common causes of hypernatremia represented by the mnemonic DRIED?

Answer 12

• Diabetes insipidus
• Renal loss
• Insensible losses
• Excess Na+ intake
• Dehydration

Question 13

What does the mnemonic SALT LOSS represent in the workup of hyponatremia?

Answer 13

• Skin losses
• Adrenal insufficiency
• Low intake
• Thiazides
• Loop diuretics
• Osmotic diuresis
• SIADH
• Seizures (if severe)

Question 14

What is the visual mnemonic for the Na/K Pump’s distribution of electrolytes?

Answer 14

[ICF]—Na/K Pump—[ECF]
K+ (140) High K Inside, High Na Outside

Question 15

True or False: The ‘60-40-20 Rule’ states that 20% of body weight is intracellular fluid.

Answer 15

False