Anion gap + delta-delta

Anion gap distinguishes HAGMA (MUDPILES) from NAGMA (HARDUPS). Delta-delta detects mixed acid-base disorders. Correct for albumin in critically ill patients.

Na (mEq/L)Cl (mEq/L)HCO₃ (mEq/L)Albumin (g/dL, optional)

Anion gap

mEq/L

Δ/Δ ratio

AG = 140 − (104 + 12) = 24.0 mEq/L (normal 8-12)
Δ/Δ = (24.0 − 12) / (24 − 12) = 1.00
Δ/Δ <1 = mixed HAGMA + NAGMA · 1-2 = pure HAGMA · >2 = HAGMA + metabolic alkalosis or pre-existing alkalosis.

HAGMA — MUDPILES

Methanol · Uremia · DKA · Propylene glycol · INH/iron · Lactic acidosis · Ethylene glycol · Salicylates

NAGMA — HARDUPS

Hyperalimentation · Acetazolamide · RTA · Diarrhea · Ureteral diversion · Pancreatic fistula · Saline