How do I find bicarbonate for a target anion gap?

Use the 'Find Bicarbonate for Target AG' tool. Enter your target anion gap, Na+, K+, and Cl- values, and it will calculate the required HCO3- level.

Anion Gap Calculator

Name: Anion Gap Calculator
Author: CalculatorBolt

Calculate the anion gap from blood test results. Enter Na⁺, K⁺, Cl⁻, and HCO₃⁻ values to get AGAP, corrected AGAP, and classification. Results help identify metabolic acid-base disorders. Informational only—consult a doctor for interpretation. Explore more tools on free calculators on CalculatorBolt.

Medical Disclaimer: This calculator is for informational and educational purposes only. Always consult a healthcare professional for medical interpretation and diagnosis.

Calculator

Sodium (Na⁺)

mEq/L

Normal: 135-145 mEq/L

Potassium (K⁺)

mEq/L

Normal: 3.5-5.0 mEq/L

Chloride (Cl⁻)

mEq/L

Normal: 96-106 mEq/L

Bicarbonate (HCO₃⁻)

mEq/L

Normal: 22-28 mEq/L

Albumin (optional)

g/dL

Normal: 3.5-5.5 g/dL (for correction)

Calculate what bicarbonate (HCO₃⁻) level is needed to achieve a target anion gap given your other electrolyte values.

Target Anion Gap

mEq/L

Desired anion gap (8-16 mEq/L is normal)

Your Na⁺

mEq/L

Sodium level

Your K⁺

mEq/L

Potassium level

Your Cl⁻

mEq/L

Chloride level

Anion Gap

Corrected AG

Classification

Import JSON

How it works

Anion Gap (AG) = (Na⁺ + K⁺) - (Cl⁻ + HCO₃⁻)

Corrected AG = AG + 2.5 × (4 - Albumin in g/dL)

We calculate the anion gap and classify it as Normal (8-16 mEq/L), High (>16 mEq/L), or Low (<8 mEq/L). The corrected AG accounts for low albumin levels which can falsely lower the calculated anion gap.

Inputs explained

Sodium (Na⁺): Primary cation in extracellular fluid. Normal range: 135-145 mEq/L.
Potassium (K⁺): Primary intracellular cation. Normal range: 3.5-5.0 mEq/L.
Chloride (Cl⁻): Primary anion in extracellular fluid. Normal range: 96-106 mEq/L.
Bicarbonate (HCO₃⁻): Buffer for acid-base balance. Normal range: 22-28 mEq/L.
Albumin (optional): Protein that contributes to anion gap. Normal: 3.5-5.5 g/dL. Used for correction formula.

Example

A patient has the following lab results:

Na⁺ = 140 mEq/L
K⁺ = 4.0 mEq/L
Cl⁻ = 102 mEq/L
HCO₃⁻ = 24 mEq/L

Calculation:

AG = (140 + 4.0) - (102 + 24) = 144 - 126 = 18.0 mEq/L
Classification: High (suggests metabolic acidosis)

Tips & notes

The anion gap helps diagnose metabolic acidosis and alkalosis by detecting unmeasured anions or cations.
Corrected AG is essential when albumin is low (e.g., liver disease, malnutrition, nephrotic syndrome).
High anion gap suggests metabolic acidosis (lactic acidosis, ketoacidosis, renal failure, toxins).
Low anion gap is less common and may indicate hypoalbuminemia, multiple myeloma, or lithium toxicity.
Always interpret results in the clinical context with other lab values and patient symptoms.
Reverse calculation: Use the "Find Bicarbonate for Target AG" tool to determine required HCO₃⁻ levels.

Anion Gap Classification

Classification	Range (mEq/L)	Clinical Significance
Low	< 8	Hypoalbuminemia, multiple myeloma, lithium toxicity
Normal	8-16	Normal acid-base balance
High	> 16	Metabolic acidosis (lactic acidosis, ketoacidosis, renal failure, toxins)

Common Causes of High Anion Gap (MUDPILES Mnemonic)

Letter	Cause	Description
M	Methanol	Toxic alcohol ingestion
U	Uremia	Renal failure
D	Diabetic ketoacidosis	Uncontrolled diabetes
P	Paraldehyde, Propylene glycol	Medication/toxin
I	Iron, Isoniazid	Toxicity
L	Lactic acidosis	Tissue hypoxia, sepsis
E	Ethylene glycol	Antifreeze poisoning
S	Salicylates	Aspirin overdose

FAQs

The anion gap is the difference between measured cations (positively charged ions) and anions (negatively charged ions) in the serum. It helps identify metabolic acid-base disorders.

A normal anion gap is typically 8-16 mEq/L, though reference ranges can vary slightly by laboratory and measurement method.

Low albumin levels can falsely lower the anion gap. Correcting for albumin provides a more accurate assessment, especially in patients with hypoalbuminemia (low albumin), such as those with liver disease or malnutrition.

A high anion gap (>16 mEq/L) often indicates metabolic acidosis and can be caused by lactic acidosis, ketoacidosis (diabetic, alcoholic), renal failure, or toxins (methanol, ethylene glycol, salicylates).

A low anion gap (<8 mEq/L) is less common and can be caused by hypoalbuminemia, multiple myeloma, lithium toxicity, or laboratory error.

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No. This is an informational tool only. Anion gap results must be interpreted by a healthcare professional in the clinical context. Never use this for self-diagnosis.

Use the "Find Bicarbonate for Target AG" tool above. Enter your target anion gap, Na⁺, K⁺, and Cl⁻ values, and it will calculate the required HCO₃⁻ level: HCO₃⁻ = (Na⁺ + K⁺) - Cl⁻ - Target AG.

Disclaimer

Medical Disclaimer: This is an informational tool based on standard medical calculations. Results should be interpreted by a healthcare professional in the clinical context. Not a substitute for medical diagnosis or treatment. Individual reference ranges may vary by laboratory. Always consult a doctor for medical advice.