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Osmolality measures solute concentration in body fluids. It's critical for diagnosing hyponatremia, hypernatremia, and fluid disorders.

공식

Calculate: Osm = 2[Na] + (Glu/18) + (BUN/2.8)
Na
Na value — Variable used in the calculation
BUN
BUN value — Variable used in the calculation

단계별 가이드

  1. 1Calculate: Osm = 2[Na] + (Glu/18) + (BUN/2.8)
  2. 2Normal: 280-310 mOsm/kg
  3. 3Compare measured to calculated osmolality

풀어진 예시

입력
Na 128, glucose 200, BUN 28
결과
Osm ≈ 318 (high), measured lower suggests hyponatremia
Pseudohyponatremia likely

피해야 할 일반적인 실수

  • Neglecting glucose and BUN contributions in hyperglycemia/uremia
  • Confusing osmolality with osmolarity (different in concentrated solutions)

자주 묻는 질문

What's the osmolal gap?

Difference between measured and calculated osmolality. Large gap suggests unmeasured osmoles (ethanol, methanol, etc.).

How does osmolality relate to sodium?

Sodium is the main determinant of osmolality; hyponatremia usually means hypoosmolality and vice versa.

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