HbA1c (IFCC) in mmol/mol

This year a world wide program is started to express hemoglobin A1c/hemoglobin.total in mmol/mol. This means drastically different values will be reported tot docters and patients. Internationally a big campaign is started to notify docters, patients and all others concerned. Currently LOINC only contains hemoglobin a1/hemoglobin.total (LOINC 4548-4 or when performed by HPLC: 17856-6) expressed in % ; % Hgb.

I can hardly believe that a LOINC code for this new assay/unit combination is not yet present in LOINC. Is this true?

Together with the new HbA1c (IFCC) a derived measure will often be reported: the Average Glucose (AvG in mmol/l or g/dL, this is country specific) Also for these assays I haven’t found LOINC codes. Are parties so occupied in their communication with docters and patients that they forget about electronic communication … using LOINC codes?

Dirk Bakkeren

Clinical chemist

Máxima Medisch Centrum, Veldhoven


We have created a LOINC code for this term , which will come out in the next release.

59261-8|Hemoglobin A1c/Hemoglobin.total|SFr|Pt|Bld|Qn|IFCC method

The units are to be reported as umol/mole which is 10x more than a % and 1000 times more than a pure fraction (the moles cancel out). But the really important difference is the fact that the value done by the IFCC method would be about 40% lower than the current method (often referred to as NGSP - reported as a % and tied to the results of the big Diabetes study). So it is not just a matter of moving the decimal place- these are really different tests

There are complexities regarding this test. Some of the instrument vendors are providing a way to report either or both the IFCC or the NGSP results- but doing this by via a conversion formula - not necessarily using the formal methods.

In any case the code exists.

The two terms you were looking for regarding estimated average glucose are in the current Relma/LOINC release- one is quite old.

27353-2|Estimated average glucose|MCnc|Pt|Bld|Qn|Estimated from glycated hemoglobin

53553-4|Estimated average glucose|SCnc|Pt|Bld|Qn|Estimated from glycated hemoglobin

Dear Kathy,

The units you mention in your answer are not the correct units for the HbA1c (IFCC) method.

The HbA1c (IFCC) is expressed in mmol (HbA1c)/mol (Hb) NOT in umol/mol. This has international agreement which really can’t be changed.

Can you please confirm that the units in mmol/mol?

Best regards

Dr Dirk Bakkeren

Dirk, my apologies. What was posted was someone else’s text. The units for the new LOINC code will be mmol/mol, as you requested.