Test Name

Bicarbonate / Serum Bicarbonate / CO₂ Content

Sample Type

Serum (via venous blood draw)

Fasting Required

❌ Not typically required

Test Method

Enzymatic or Ion-Selective Electrode

Department

Biochemistry / Nephrology / Pulmonology

Normal Range

22–29 mmol/L (may vary slightly by lab)

Lungs

Regulate CO₂ → affects bicarbonate via respiration

Kidneys

Filter and reabsorb bicarbonate → maintain acid-base balance

Metabolic System

Involved in buffering acids formed during normal metabolism

🧪 Evaluate Acid-Base Disorders

Part of diagnosing metabolic acidosis or alkalosis

🩺 Kidney Function Assessment

In chronic kidney disease (CKD), bicarbonate levels drop

🫁 Respiratory Conditions

Used with ABG to assess respiratory vs. metabolic components

💉 Monitor Critical Illness

Used in ICU, dehydration, shock, or electrolyte imbalance cases

Diabetic ketoacidosis

Chronic kidney disease

Lactic acidosis

Severe diarrhea (bicarbonate loss from gut)

Poisoning (e.g., methanol, salicylates)

Sepsis or shock

Prolonged vomiting (loss of gastric acid)

Excessive antacid use

Diuretic therapy (e.g., thiazides, loop)

Hypokalemia

Arterial Blood Gas (ABG)

Direct measure of blood pH, pCO₂, HCO₃⁻

Electrolyte Panel

Sodium, potassium, chloride → for acid-base interpretation

Anion Gap Calculation

Helps differentiate types of metabolic acidosis

Kidney Function Tests

Creatinine, BUN, eGFR

Lactate

Elevated in lactic acidosis

Urine pH

Assess renal handling of acid/base

Sample

Serum (venous blood)

Fasting Needed

❌ No

Used For

Acid-base evaluation, kidney and respiratory conditions

Normal Range

22–29 mmol/L

High Levels

Alkalosis, vomiting, diuretic use

Low Levels

Acidosis, kidney disease, diarrhea, DKA