Anion Gap

Electrolytes marker

Anion Gap

Category: Electrolytes
Unit: mmol/L

Calculated value (Na - Cl - HCO3) that helps identify causes of metabolic acidosis.

PED Notes

Can be transiently elevated after intense training due to lactic acid accumulation. Persistent elevation warrants investigation. Not directly affected by AAS.

When elevated (>17 mmol/L):

Common causes in athletes:

  • Post-training lactic acidosis -- transient, resolves within hours; ensure rest-day blood draw
  • Ketoacidosis -- possible if on very low carb diet or if GH has impaired glucose tolerance; check fasting glucose and ketones
  • Kidney dysfunction -- impaired acid excretion; check creatinine, eGFR, and Cystatin C
  • Dehydration -- can concentrate unmeasured anions

Management:

  • Ensure blood draw is fasted and on a rest day for accurate baseline
  • If persistently elevated, investigate kidney function and glucose metabolism
  • Adequate hydration (3-4L/day)
  • If on very low carb / ketogenic diet, consider adding moderate carbohydrates

References:

  • American Diabetes Association. (2026). Standards of Care in Diabetes—2026. Diabetes Care, 49(Suppl. 1), S1-S5. DOI: 10.2337/dc26-SINT

History Chart

Reading History

Frequently Asked Questions

Reference Ranges

Standard Range

7 - 17 mmol/L

VitalMetrics Range

7 - 19 mmol/L

Statistics