QuestionA recent test for Vitamin B 12 came back as 70000 NG/L.
(Seventy thousand).
Isn't this physically impossible?
(Am wondering if someone made a mistake with the figures or the NG measure used.)
AnswerHi,
Please be aware that the information provided is not a substitute for medical advice and should not be interpreted as medical advice. This information is being provided for informational purposes only. Your own physician is the best resource to interpret your specific laboratory results and should be consulted for medical advice regarding your own specific health condition.
The website below contains reference ranges for common lab tests.
http://pathcuric1.swmed.edu/PathDemo/nrrt.htm#Hematology
The reference range for B12 is:
Reference Range:
Normal: 243-894 pg/ml Indeterminant: 175-242 pg/ml Deficient: < 174 pg/ml
http://www.medicine.uiowa.edu/path_handbook/rhandbook/test1953.html
pg/mL
1 ng = 1,000 pg
1 L = 1,000 mL
So:
70,000 ng/L x 1,000 pg/ng x 1L/1,000 mL = 70,000 pg/mL
Possible problems:
If the result was hand calculated, someone got their units wrong or misplaced a decimal point.
There are also laboratory testing interferences with many laboratory tests.
Questions:
Do you recall what the color of the top of the vacutainer tube was that the blood specimen was collected in?
Do you recall if the blood specimen was collected in a gel separator tube? It would have looked like this with a gel separator in the bottom of the tube before the blood specimen was collected:
http://www.firstqualitylaboratory.com/services/specollection/image003.jpg
If the specimen was collected in a gel separator tube and wasn't re-centrifuged before testing, it could have caused a falsely elevated result.
http://acb.rsmjournals.com/cgi/content/abstract/40/5/560
Conclusions: Use of serum separator tubes may be associated with spuriously elevated serum vitamin B12 concentrations in the Bayer Centaur assay. Laboratories receiving samples for vitamin B12 assay in serum separator tubes that have already been centrifuged should either re-centrifuge the tubes, or aliquot and re-centrifuge serum from the tubes prior to vitamin B12 assay.
You may want to ask them:
1. if they collected the specimen in a gel separator tube and if so if the specimen was re-centrifuged prior to running the test
2. to rerun the test
To insure accuracy, the specimen must be collected under appropriate conditions using an appropriate technique in the correct specimen container and in the correct volume for the test ordered, transported and stored under appropriate temperature conditions and within the specified time limits, processed correctly and within the specified time limits, and the testing done within the specified time limits and according to standard laboratory testing procedures.
This is critical for accurate laboratory testing results.
Methodology:Electrochemiluminescence immunoassay
Sample Processing:Centrifuge within two hours of draw time.
Centrifuge at 3000 RPM for 10 minutes.
Aliquot serum/plasma into screw-capped plastic vial.Sample Storage:Refrigerate.Transport Instructions:Place requisition into outside pocket of bag.
Place specimen into zip-lock type bag, seal bag.
Place dry ice on top of specimen in styrofoam container.
Dry Ice up to 24 hours.
Instructions:Centrifuge, remove serum or plasma, aliquot to plastic tube labeled with patient's name and date drawn.
Refrigerate and protect from light.CPT Code:82607
Has your doctor seen the results? What did your doctor say about this?
Regardless of the reason, the standard procedure for a suspected spurious or abnormal result is to rerun the test.
