THE VITAMIN B12 AND FOLATE PATHOLOGY INVESTIGATION
THE INVESTIGATION OF ERRORS IN PATHOLOGY TESTS
FOR VITAMIN B12 AND FOLATE DEFICIENCY
BY MEANS OF MEDICAL EXPERIMENTS
THE SERUM VITAMIN B12 INVESTIGATION
SERUM B12 ERRORS
Summary
Serum B12 Lab Errors
Laboratory Performance
Interpretation Errors
Immunoassays

Index

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Introduction

This investigation was performed by regularly measuring several biochemical markers of vitamin B12 deficiency, as deficiency developed, following cessation of treatment. For details of the method used and results, please refer to The Serum B12 Experiment .

These are the tests that I compared to serum vitamin B12, for effectiveness in diagnosis of vitamin B12 deficiency:

  • Serum Methylmalonic Acid (MMA)
  • Serum Total Homocysteine (tHcy)

Results from these laboratories were used for the comparisons:

  • Sullivan Nicolaides Pathology (SNP), Brisbane - serum vitamin B12, tHcy
  • NSW Biochemical Genetics Service, Children's Hospital Westmead (CHW), Sydney - MMA, tHcy

Serum samples were collected on 39 sample dates, from 24 October 2005 to 27 November 2006.

Notes for Charts and Tables

Results are presented as charts and tables. You can view a larger chart in a new window by selecting the link shown above the chart. You can view the complete Excel table in a new window by selecting the link shown above the chart.

Most of the tables will initially appear at low resolution in the new window. To enlarge the table to full size, move the cursor from the white space below the table to inside the lower right corner of the table; an icon will then appear in the lower right corner of the table. Click on the icon to view the table full-size. Use the horizontal scroll-bar, in the new window, to view the entire table.

The chart and table numbers used here correspond to the sheet numbers in the Excel file, Series 1 - Serum B12 Investigation, which may be downloaded from Evidence.

These results can be verified from the scanned original pathology reports, which may be downloaded from Evidence.

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Serum Vitamin B12 Compared to Serum Methylmalonic Acid

The following chart shows how serum vitamin B12 compared to serum methylmalonic acid, as vitamin B12 deficiency developed.

Chart C24 Table C8

The important points to note, about response of serum B12, from these SNP results are:

  • Fell rapidly to 323 pmol/L, after ceasing oral B12 on 10 February 2006
  • Continued to fall at much slower rate
  • Never fell below SNP normal range
  • Increased rapidly after re-commencing oral B12 on 13 November 2006

The important points to note, about response of MMA, from these CHW results are:

  • Increased to remain consistently above the CHW normal range, after ceasing oral B12 on 10 February 2006
  • Reached a peak, then leveled off
  • Fell rapidly after re-commencing oral B12 on 13 November 2006

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Serum Vitamin B12 Compared to SNP Serum Total Homocysteine

The following chart shows how serum vitamin B12 compared to Sullivan Nicolaides Pathology serum total homocysteine, as vitamin B12 deficiency developed.:

Chart C25

The important points to note, about response of serum B12, from these SNP results are:

  • Initially borderline low quoted by SNP
  • Increased rapidly after commencing oral B12 on 2 November 2005
  • Fell rapidly to 323 pmol/L, after ceasing oral B12 on 10 February 2006
  • Continued to fall at much slower rate
  • Never fell below SNP normal range
  • Increased rapidly after re-commencing oral B12 on 13 November 2006

The important points to note, about response of homocysteine, from these SNP results are:

  • Initially 11.9, then 12.3 umol/L, well below maximum limit quoted by SNP.
  • Fell rapidly after commencing oral B12 on 2 November 2005, reaching minimum of 7.0 umol/L.
  • Increased again, remaining within the range 7.9 to 9.2 umol/L for several months.
  • Never exceeded the normal range quoted by SNP.
  • Fell rapidly after re-commencing oral B12 on 13 November 2006

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Serum Vitamin B12 Compared to CHW Serum Total Homocysteine

The following chart shows how serum vitamin B12 compared to Westmead serum total homocysteine, as vitamin B12 deficiency developed.:

Chart C26

The important points to note, about response of serum B12, from these SNP results are:

  • Initially borderline low quoted by SNP
  • Increased rapidly after commencing oral B12 on 2 November 2005
  • Fell rapidly to 323 pmol/L, after ceasing oral B12 on 10 February 2006
  • Continued to fall at much slower rate
  • Never fell below SNP normal range
  • Increased rapidly after re-commencing oral B12 on 13 November 2006

The important points to note, about homocysteine response for Sample A and Sample B, from these Westmead results are:

  • Both samples showed significantly different trend
  • After an initial fall, Sample A increased to remain consistently above the CHW limit
  • Sample B showed much less distinct initial increase that Sample A
  • Sample B reached a peak later than Sample A
  • Sample B fell rapidly after re-commencing oral B12
  • Last four A samples were destroyed by Mater Pathology.

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Conclusion

Serum Vitamin B12 Compared to Serum Methylmalonic Acid

Serum vitamin B12 is a much less sensitive indicator of vitamin B12 deficiency than methylmalonic acid.

Although serum vitaminB12 was sensitive to the intake of high dose oral B12, it failed to detect the onset of B12 deficiency after the oral B12 was ceased. This insensitivity is illustrated by the very slow decline in serum B12 level, while the methylmalonic acid increased rapidly above the cut-off.

Serum vitamin B12 may be useful to confirm that high-dose oral B12 is absorbed, but cannot be used to detect the onset of cellular vitamin B12 deficiency. A "normal" serum vitamin B12 result is deceptive because it cannot reliably reflect the true metabolic state of the patient.

Serum Vitamin B12 Compared to Serum Total Homocysteine

The comparison of serum vitamin B12 with total homocysteine is not as clear as the comparison with methylmalonic acid. This is because of doubts about the results from Sullivan Nicolaides Pathology and the quality of samples supplied to Westmead.

Although there were significant differences between them, results from both laboratories showed a significant increase in total homocysteine in the latter part of the experiment.

Serum vitamin B12 failed to detect the onset of cellular deficiency, while total homocysteine did detect a change in metabolic state.

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