Vitamin B12 - Change to Reference Interval

We have undertaken an extensive review of the reference intervals for Vitamin B12 in use at Pathlab and intend to reduce our lower reference interval from 140pmol/L to 110pmol/L Feedback from GPs suggests a higher than expected number of patients with low or marginally Vitamin B12 levels. The method we use is known to produce lower results than other methods and our quoted reference intervals are also lower. However, there is growing evidence that our reference interval should be even lower than they are.

We undertook a comparison of patient samples comparing our method with those from Waikato Hospital Laboratory and compared our reference interval with that method. – see below:

There was very good correlation between methods (R2 = 0.9835) but the chart clearly showed that our method was approximately 30% lower than the other method.

In August we intend to reduce our lower reference interval from 140 pmol/L to 110 pmol/L which we believe is a better reflection of patient results.