2 × Na + glucose (mg/dL)/18 + urea (mg/dL)/6. Uses blood urea, as reported by most Indian labs.
mmol/L
mg/dL
mg/dL
Calculated osmolality
291 mOsm/kg
Normal (≈ 275-295)
Low
Normal (≈ 275-295)
High
Markedly high (HHS range > 320)
Formula
2 * na + glucose / 18 + urea / 6
Notes
If your lab reports BUN instead of urea: urea = BUN × 2.14, or use BUN/2.8.References
Used in
Calculators support, not replace, clinical judgement. Check inputs and units, and confirm doses with your unit protocol.