B12 test...why so many ranges?

[Jackie419]

...and never the same range? What does this test mean? Thanks (Barb) lol!!

B12 Lvl   715      50-1500 pg/ml

[Jackie419]

Barb, I don't know if I have pernicious anemia, I would have to have compentent doctors to know that. I do know my B12 was down to around 200 a couple of years ago and I was hoping it was low again because I have had a metallic taste for almost 2 weeks straight and while I am prone to that problem, not for that long!! I will definitely up the dose.

Red_Star---that makes sense, this hospital still has 5.60 as the top ref. # for TSH, thank you for helping me to stop obsessing about their numbers. I am so sick of doctors and hospitals. I'll post my other tests in new thread. Thanks you two!

[Red_Star]

There are two assays for B12 deficiency: radioassay and the nonradioisotopic assay chemiluminescence.

Radioassay range: 200 - 900 pg/mL (147.6 - 664.2 pmol/L)
Chemiluminescence range: 250 - 1100 pg/mL (184.5 - 811.8 pmol/L)

My B12 serum reference range at QML pathology is 162 - 812 pmol/L (220 - 1100 pg/ml).  I did find the analytical measurement range of vitamin B12 is 50 - 1500 pg/ml.

"The ANALYTICAL MEASUREMENT RANGE (AMR) is the range of analyte values that a method can directly measure on the specimen without any dilution, concentration, or other pretreatment not part of the usual assay process."

[Barb135]

Reference ranges vary from lab to lab, depending on the methodology each lab uses for analyzing samples, just like ranges for FT3 and FT4 vary lab to lab.  

At 715, I'm sure your doctor will say that's "normal" and yes, it is; however, I, personally, don't feel well with levels that low.  I have to keep mine around 1000-1200 in order to feel "human".  You have to sort of base your level on how you feel.  If you have symptoms of a B-12 deficiency, try upping your level to see if symptoms go away; if they don't start looking elsewhere for the cause of the symptoms.

Are you supplementing your B-12?  Do you  have Pernicious Anemia, which is another autoimmune disease?  

[Red_Star]

The standard lower range for vitamin B12 serum was set around 220 pg/mL (162 pmol/L) although this varies slightly between labs. New research has found that vitamin B12 deficiency may occur at much higher vitamin B12 levels: 500 - 600 pg/mL (369 - 442.8 pmol/L).  A vitamin B12 serum of 50 pg/mL (36.9 pmol/L) looks to be a lab reference error.