learn.howToCalculate
learn.whatIsHeading
Osmolality measures solute concentration in body fluids. It's critical for diagnosing hyponatremia, hypernatremia, and fluid disorders.
Formula
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
Guida passo passo
- 1Calculate: Osm = 2[Na] + (Glu/18) + (BUN/2.8)
- 2Normal: 280-310 mOsm/kg
- 3Compare measured to calculated osmolality
Esempi risolti
Ingresso
Na 128, glucose 200, BUN 28
Risultato
Osm ≈ 318 (high), measured lower suggests hyponatremia
Pseudohyponatremia likely
Errori comuni da evitare
- ✕Neglecting glucose and BUN contributions in hyperglycemia/uremia
- ✕Confusing osmolality with osmolarity (different in concentrated solutions)
Domande frequenti
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.
Pronto per calcolare? Prova la calcolatrice gratuita di Osmolality
Provalo tu stesso →