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Valproate µg/mL → µmol/L

Convert valproate from µg/mL to µmol/L

Sources last checked: 2026-11-03

Valproate µg/mL → µmol/L

Convert valproate from µg/mL to µmol/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 Valproate µg/mL → µmol/L?

Valproate levels are measured as valproic acid and reported in µg/mL (identical to mg/L) by most laboratories in Germany, Austria, Turkey and the USA, and in µmol/L by some SI-reporting laboratories. This converter multiplies by 6.934, the factor that follows from the molar mass of valproic acid (144.21 g/mol).

When to use it

  • Comparing a valproate level in µg/mL with a source written in µmol/L
  • Documenting therapeutic drug monitoring for a patient moving between laboratories
  • Pharmacokinetic exercises in SI units
  • Exam questions on antiepileptic drug monitoring

When not to use it

  • Converting a dose of sodium valproate or valproate semisodium — the salt forms have different molar masses, and doses are not concentrations
  • Interpreting a total level in hypoalbuminaemia without considering the free fraction
  • Judging toxicity from the level alone: hyperammonaemia, hepatotoxicity and pancreatitis do not correlate reliably with concentration

How it is calculated

Valproate (µmol/L) = valproate (µg/mL) × 6.934

Clinical pearls and limitations

  • Converts units only; reference ranges depend on the laboratory, the assay and the patient.
  • 1 µg/mL = 1 mg/L = 6.934 µmol/L; conversely 1 µmol/L = 0.1442 µg/mL.
  • Valproate protein binding is concentration-dependent and falls with low albumin, uraemia and liver disease, so the free fraction can rise without a matching rise in the total level.
  • Valproate levels fluctuate considerably across the dosing interval, especially with immediate-release forms, so record the time since the last dose and preferably sample at trough.
  • Carbapenems lower valproate levels markedly and quickly; a sudden drop during antibiotic treatment is a known interaction.

Frequently asked questions

How do I convert valproate from µg/mL to µmol/L?

Multiply by 6.934. For example, 72 µg/mL × 6.934 = 499 µmol/L.

Why is the valproate factor 6.934?

The laboratory measures valproic acid, with a molar mass of 144.21 g/mol. 1 µg/mL equals 1 mg/L, and 1000 ÷ 144.21 = 6.934 µmol/L.

Does it matter whether the patient takes sodium valproate or valproic acid?

Not for the level: the assay reports valproate as valproic acid whatever form was prescribed. The salt form matters only when comparing doses.

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: valproic acid (CID 3121), molecular weight 144.21 g/mol.

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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.