如何计算Osmolality
learn.whatIsHeading
Osmolality measures solute concentration in body fluids. It's critical for diagnosing hyponatremia, hypernatremia, and fluid disorders.
公式
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
分步指南
- 1Calculate: Osm = 2[Na] + (Glu/18) + (BUN/2.8)
- 2Normal: 280-310 mOsm/kg
- 3Compare measured to calculated osmolality
例题解析
输入
Na 128, glucose 200, BUN 28
结果
Osm ≈ 318 (high), measured lower suggests hyponatremia
Pseudohyponatremia likely
常见错误注意事项
- ✕Neglecting glucose and BUN contributions in hyperglycemia/uremia
- ✕Confusing osmolality with osmolarity (different in concentrated solutions)
常见问题
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.
准备好计算了吗？尝试免费的 Osmolality 计算器
自己尝试一下 →