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Fluids & Electrolytes

Anion Gap

Serum anion gap with optional albumin correction, delta gap and delta ratio.

Inputs

FieldUnitNotes
Sodium mmol/L 120–160
Chloride mmol/L 90–120
Bicarbonate mmol/L 10–40
Albumin g/L Optional, for corrected AG

FAQ

What is the Anion Gap?

Serum anion gap with optional albumin correction, delta gap and delta ratio.

What inputs does the Anion Gap need?

Sodium (mmol/L), Chloride (mmol/L), Bicarbonate (mmol/L), Albumin (g/L).

Related guides

Anion Gap in Metabolic Acidosis: Albumin Correction and the Delta-Delta

Serum anion gap done properly — HAGMA vs NAGMA, why hypoalbuminemia masks a raised gap (correct +2.5 per g/dL below normal), and using the delta ratio to unmask a hidden second acid-base disorder.

Related Fluids & Electrolytes calculators

Corrected Calcium (Payne)

Albumin-corrected serum calcium using the Payne correction (SI units).

Maintenance Fluid (Holliday-Segar)

Daily maintenance fluid requirement using the Holliday-Segar method.

Hyponatremic Dehydration

Estimates safe sodium-correction rate and fluid replacement for a child with hyponatremia (Na < 135).

Hypernatremic Dehydration

Estimates free-water deficit and fluid replacement for a child with hypernatremia (Na > 145).

Sodium Correction for Hyperglycaemia

Adjusts measured serum sodium for the dilutional effect of hyperglycaemia (e.g. in DKA).

Free Water Deficit (Hypernatraemia)

Estimates the free-water deficit in a hypernatraemic child, to guide the volume needed to return sodium to 140 mEq/L.

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