Convert 20 common laboratory analytes between conventional units (mg/dL, g/dL, µg/dL) and SI units (mmol/L, µmol/L, g/L), including the non-linear HbA1c equation. Every factor is shown with its source.
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Chemistry
Glucose
GLUCAbove range high. Was this entered in mg/dL? 126 mg/dL = 7.0 mmol/L.
Creatinine
CREATCholesterol, total
CHOLHbA1c
HBA1CLab unit conversion in brief
Free tool
Choose an analyte and a direction, then enter the value. The factor and its source appear under the result, and the full factor table is below the converter. Reference only; nothing is saved or sent.
mg/dL × 0.0555 = mmol/L
Source: AMA Manual of Style SI conversion table.
| Analyte | Conventional | × factor | SI |
|---|---|---|---|
| Glucose | mg/dL | 0.0555 | mmol/L |
| Creatinine | mg/dL | 88.4 | µmol/L |
| Urea nitrogen (BUN) → urea | mg/dL | 0.357 | mmol/L |
| Cholesterol, total | mg/dL | 0.0259 | mmol/L |
| Cholesterol, LDL | mg/dL | 0.0259 | mmol/L |
| Cholesterol, HDL | mg/dL | 0.0259 | mmol/L |
| Triglycerides | mg/dL | 0.0113 | mmol/L |
| Bilirubin, total | mg/dL | 17.104 | µmol/L |
| Calcium, total | mg/dL | 0.25 | mmol/L |
| Magnesium | mg/dL | 0.4114 | mmol/L |
| Uric acid (urate) | mg/dL | 59.5 | µmol/L |
| Haemoglobin (g/L) | g/dL | 10 | g/L |
| Haemoglobin (mmol/L, monomer) | g/dL | 0.6206 | mmol/L |
| Albumin | g/dL | 10 | g/L |
| Iron | µg/dL | 0.179 | µmol/L |
| 25-Hydroxyvitamin D | ng/mL | 2.496 | nmol/L |
| Testosterone | ng/dL | 0.0347 | nmol/L |
| Cortisol | µg/dL | 27.588 | nmol/L |
| Potassium | mEq/L | 1 | mmol/L |
| Sodium | mEq/L | 1 | mmol/L |
| HbA1c (NGSP % ↔ IFCC mmol/mol) | % (NGSP/DCCT) | formula | mmol/mol (IFCC) |
Reference only, not validated software and not for clinical decisions. Factors from the AMA Manual of Style SI conversion table except where stated; HbA1c uses the NGSP master equation. Results are rounded for display. Your central or local laboratory's own units and conversions take precedence.
Why it matters in trials
Laboratories in the United States mostly report conventional units, such as glucose in mg/dL and creatinine in mg/dL. Most of Europe, Australia and many other regions report SI units, such as mmol/L and µmol/L. A multinational trial, or even a domestic trial using several local laboratories, will receive the same analyte in different units. If nobody converts consistently, the result is a pooled dataset where a glucose of 7 and a glucose of 126 mean the same thing.
The conversion factors in the tool come from the AMA Manual of Style SI conversion table, the reference most medical journals use, apart from two that the table does not list: HbA1c, which uses the NGSP master equation, and haemoglobin in mmol/L, explained below. Each factor reflects the molar mass of the analyte. For example, 1 mg/dL of glucose is 10 mg/L, and 10 divided by glucose's molar mass of about 180 g/mol gives 0.0555 mmol/L.
In CDISC SDTM, the LB domain keeps the result and unit as collected (LBORRES, LBORRESU) and a standardised version (LBSTRESN, LBSTRESU). That is why the eCRF should capture the value exactly as the laboratory reported it, together with its unit, and leave standardisation to a documented, reproducible step rather than to mental arithmetic at the site.
Decide early where conversion happens. Converting at the site, before entry, is the riskiest option: it adds a manual calculation to every value and hides the original result. Converting during analysis, from the reported value and unit, is reproducible and easy to audit. If the protocol needs one unit on the form, for example because an eligibility cut-off or a calculated field depends on it, put the conversion factor in the lab manual so that every site uses the same one.
Worked examples
| Analyte | Conventional | Factor | SI | Example |
|---|---|---|---|---|
| Glucose | mg/dL | 0.0555 | mmol/L | 126 mg/dL = 7.0 mmol/L |
| Creatinine | mg/dL | 88.4 | µmol/L | 1.2 mg/dL = 106 µmol/L |
| Cholesterol (total, LDL, HDL) | mg/dL | 0.0259 | mmol/L | 200 mg/dL = 5.18 mmol/L |
| Triglycerides | mg/dL | 0.0113 | mmol/L | 150 mg/dL = 1.70 mmol/L |
| Bilirubin, total | mg/dL | 17.104 | µmol/L | 1.2 mg/dL = 20.5 µmol/L |
| Calcium, total | mg/dL | 0.25 | mmol/L | 10.0 mg/dL = 2.50 mmol/L |
| 25-Hydroxyvitamin D | ng/mL | 2.496 | nmol/L | 30 ng/mL = 75 nmol/L |
| Cortisol | µg/dL | 27.588 | nmol/L | 15 µg/dL = 414 nmol/L |
| HbA1c | % (NGSP) | equation | mmol/mol (IFCC) | 7.0% = 53 mmol/mol; 6.5% = 48 mmol/mol |
Factors from the AMA Manual of Style SI conversion table; HbA1c from the NGSP master equation. Rounded for display.
Interpretation pitfalls
HbA1c is the main non-linear case. The NGSP publishes the master equation NGSP (%) = 0.09148 x IFCC (mmol/mol) + 2.152, so IFCC = (NGSP - 2.152) / 0.09148. The intercept means you cannot multiply by a single factor: 7.0% is 53 mmol/mol, 6.5% is 48 and 8.0% is 64. The tool uses the equation in both directions.
Check these before you lock the lab form.
Upload your lab sheet to the AI form builder in the free sandbox and review the drafted analyte table. No credit card. You pay only when you go live.
Lab data in Capture
In Capture you can upload a lab manual or range sheet (CSV, XLSX, PDF or DOCX) and the AI form builder drafts a lab table with analytes as rows and unit, result and reference-range columns, split by sex and age where the source has them. Nothing is saved until someone on your team reviews the draft, and it only works on draft forms. The lab results eCRF template is another starting point.
Edit checks with range high and range low limits raise a query automatically when a value falls outside a plausible range, which catches the classic error of a mg/dL value typed into a mmol/L field. Lab tables are repeating rows, and each row carries its own audit trail. Calculated fields such as eGFR (CKD-EPI 2021) and creatinine clearance (Cockcroft-Gault) depend on the creatinine unit the formula expects, so agree that unit when you build the form. For per-laboratory ranges and alert values, see lab data and reference range management, and for how reference intervals are derived, the glossary entry on the reference interval.
Lab form build
One expected unit for each analyte, or a unit field captured with each result.
Capture the value as the lab reported it; standardise in a documented step.
Reference ranges stored in the unit of the result they apply to.
Range edit checks wide enough for real values, tight enough to catch unit errors.
NGSP % or IFCC mmol/mol, stated in the protocol.
Confirm the unit each calculated field, such as eGFR, expects.
Multiply by 0.0555. For example, 126 mg/dL x 0.0555 = 7.0 mmol/L. To go back, divide mmol/L by 0.0555, or multiply by about 18.
Multiply by 88.4. A creatinine of 1.2 mg/dL is about 106 µmol/L. Divide by 88.4 to go from µmol/L to mg/dL.
Use the NGSP master equation: IFCC mmol/mol = (NGSP % - 2.152) / 0.09148. So 7.0% is 53 mmol/mol and 6.5% is 48 mmol/mol. It is not a single multiplication factor.
From the AMA Manual of Style SI conversion table, except HbA1c (NGSP master equation) and haemoglobin in mmol/L (monomer basis, 0.6206 per g/dL). The source appears under each result.
No. BUN is urea nitrogen. BUN in mg/dL x 0.357 gives urea in mmol/L, but urea measured as urea in mg/dL uses a different factor. Check which one your laboratory reports.
No. It is a reference tool, not validated software or a medical device. Your laboratory's own reported units and conversions take precedence.
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