How is the anion gap calculated and what is the normal value?

AG = Na - (Cl + HCO3); normal AG = 8-12 mEq/L (without albumin correction); corrected AG = measured AG + 2.5 × (4 - albumin g/dL); AG >20 strongly suggests high-AG metabolic acidosis regardless of pH.

What is the Winter formula for respiratory compensation?

In metabolic acidosis: expected pCO2 = 1.5 × HCO3 + 8 (±2); if pCO2 higher than predicted: concurrent respiratory acidosis; if lower: concurrent respiratory alkalosis; pH determines which disorder is primary.

What is the delta-delta ratio?

Delta-delta = (AG - 12) / (24 - HCO3); ratio 2: metabolic alkalosis coexisting with AG acidosis.

What is the MUDPILES mnemonic for high anion gap causes?

Methanol, Uremia, DKA, Propylene glycol/Paraldehyde, Isoniazid/Iron, Lactic acidosis, Ethylene glycol, Salicylates; also GOLD MARK (Glycols, Oxoproline, L-lactate, D-lactate, Methanol, Aspirin, Renal failure, Ketoacidosis).

How is respiratory compensation for metabolic alkalosis assessed?

Expected pCO2 = 0.7 × HCO3 + 21 (±2); or △pCO2 = 0.7 × △HCO3; pCO2 rarely exceeds 55-60 mmHg as a compensatory response; higher pCO2 indicates primary respiratory acidosis coexisting with metabolic alkalosis.

Arterial Blood Gas Interpretation and Acid-Base Disorder Calculator

Interprets arterial blood gas results identifying primary acid-base disorders and expected compensation (Winter formula, 1.5 rule), calculates anion gap, delta-delta ratio, and identifies mixed disorders.

Weight

Height

Clinical Guidance

BMI is a screening measure of body size, not a direct measure of body fat. The standard WHO categories are underweight (<18.5), normal (18.5–24.9), overweight (25–29.9), and obese (≥30).

BMI can overestimate body fat in athletes with high muscle mass and underestimate it in older adults with low muscle mass. Interpret it alongside waist circumference and clinical context rather than as a standalone diagnosis.

⚕ Clinical Disclaimer: These calculators are for educational and reference purposes only. Always verify results with qualified clinical judgment and current clinical guidelines. Do not use as a sole basis for medical decisions.

How to Use

Enter the values for the patient or scenario you are assessing. Interprets arterial blood gas results identifying primary acid-base disorders and expected compensation (Winter formula, 1.5 rule), calculates anion gap, delta-delta ratio, and identifies mixed disorders. Use the abg interpretation result to inform your clinical assessment.

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