Electrolytes

CRNA Study Suite · Osmolarity · Anion Gap · Corrected Na
All Calculators Electrolytes
Lab Values
Normal Ranges
Na135-145
K3.5-5.0
Cl98-107
HCO₃22-28
Glucose70-110
Serum Osm275-295 mOsm/L
Anion Gap8-12 (w/ albumin 4)
(Trinooson & Patel, 2023, pp. 376-399)
Results
Serum Osmolarity
--
mOsm/L
Anion Gap
--
mEq/L
Corrected AG (albumin)
--
mEq/L
Corrected Na (for hyperglycemia)
--
mEq/L
Calculation Breakdown
Serum Osmolarity
Osm = 2 × Na + (Glucose / 18) + (BUN / 2.8)
--
Osm = -- mOsm/L    (Normal 275-295)
Anion Gap
AG = Na − (Cl + HCO₃)
--
AG = -- mEq/L    (Normal 8-12 w/ alb 4)
Anion Gap Mnemonic for Elevated AG Metabolic Acidosis
MUDPILES: Methanol, Uremia, DKA, Paraldehyde/Propylene glycol, Iron/Isoniazid/Inhalants, Lactic acidosis, Ethylene glycol, Salicylates
References

Trinooson, C., & Patel, N. G. (2023). Fluids, electrolytes, and goal-directed therapy. In S. Elisha, J. S. Heiner, & J. J. Nagelhout (Eds.), Nurse anesthesia (7th ed., pp. 376-399). Elsevier.

How this works

Normal serum ranges

Normal serum electrolytes are sodium 135 to 145 mEq/L, potassium 3.5 to 5.0 mEq/L, total calcium 9.0 to 10.5 mg/dL, magnesium 1.5 to 3.0 mEq/L, and phosphate about 2.0 to 4.7 mg/dL (Trinooson & Patel, 2023, pp. 393-398).

Potassium and magnesium perioperatively

A preoperative potassium below 4.0 or above 5.5 mEq/L is associated with increased 30 day major adverse cardiac events, and hyperkalemia produces a predictable ECG progression from peaked T waves to a sine wave pattern and arrest above 8.5 mEq/L (Trinooson & Patel, 2023, pp. 394-395). Magnesium potentiates nondepolarizing neuromuscular blockers, so hypermagnesemic patients need careful monitoring; hypomagnesemia produces flat T waves, U waves, a prolonged QT, and arrhythmias (Trinooson & Patel, 2023, pp. 396-397).

References

Trinooson, C., & Patel, N. G. (2023). Fluids, electrolytes, and goal-directed therapy. In Elisha, Heiner, & Nagelhout (Eds.), Nurse anesthesia (7th ed., pp. 376-399). Elsevier.