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Lactate mg/dL → mmol/L

Convert lactate from mg/dL to mmol/L

Sources last checked: 2026-11-03

Lactate mg/dL → mmol/L

Convert lactate from mg/dL to mmol/L

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Converts units only; reference ranges depend on the laboratory, the assay and the patient.

Source: AMA Manual of Style, 11th ed. (Oxford Academic) — Units of measure converter, Table 2: Selected laboratory tests and conversion factors.Open

What is the Lactate mg/dL → mmol/L?

Lactate is reported in mmol/L by blood gas analysers and by many European laboratories, while some central laboratories, including several in Turkey and the USA, report it in mg/dL. This converter multiplies by 0.111, which follows from the molar mass of lactic acid (90.08 g/mol) and matches the AMA Manual of Style SI table. Sepsis and critical-care literature is written almost entirely in mmol/L.

When to use it

  • Reading a central-laboratory lactate in mg/dL next to a blood gas result in mmol/L
  • Applying sepsis or critical-care literature that uses mmol/L
  • Following lactate trends when results come from different analysers
  • Exam questions that give lactate in conventional units

When not to use it

  • D-lactate, which standard enzymatic assays do not measure
  • Lactate–pyruvate ratios, which are dimensionless and need no conversion
  • As a diagnosis on its own; a raised lactate has many causes besides hypoperfusion

How it is calculated

Lactate (mmol/L) = lactate (mg/dL) × 0.111

Clinical pearls and limitations

  • Converts units only; reference ranges depend on the laboratory, the assay and the patient.
  • 1 mg/dL ≈ 0.111 mmol/L; 9 mg/dL ≈ 1.0 mmol/L.
  • The factor uses lactic acid (90.08 g/mol); the lactate anion is lighter by one hydrogen atom, a difference that is clinically irrelevant.
  • Delayed analysis without a glycolysis inhibitor, or prolonged tourniquet time, can raise lactate in the tube.
  • Thresholds for action depend on the guideline and clinical setting; take them from the source in its original unit.

Frequently asked questions

How do I convert lactate from mg/dL to mmol/L?

Multiply by 0.111. For example, 27 mg/dL × 0.111 = 3.0 mmol/L and 9 mg/dL × 0.111 = 1.0 mmol/L.

Why is the lactate factor 0.111?

Lactic acid has a molar mass of 90.08 g/mol. 1 mg/dL is 10 mg/L, and 10 ÷ 90.08 = 0.111 mmol/L.

Are arterial and venous lactate interchangeable?

They usually agree closely, but the unit conversion is the same either way; how a venous value maps to a guideline written for arterial samples is a clinical question, not a unit question.

Evidence and guidelines

  1. Primary source: AMA Manual of Style, 11th ed. (Oxford Academic) — Units of measure converter, Table 2: Selected laboratory tests and conversion factors.
  2. PubChem compound summary: lactic acid (CID 612), molecular weight 90.08 g/mol.

Have a follow-up question?

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For healthcare professionals and medical students. These tools support, and do not replace, clinical judgement. Always check results against the original source and your local protocols.