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 HOMOCYSTEINE INVESTIGATION
HCY ERRORS
Summary
Laboratory Performance
PaLMS
Interpretation Errors
Immunoassays

Index

This page contains the following sections:

You can go to a section by selecting the link.

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Introduction

Here you will find my specific claims about what I consider to be the poor performance by Pacific Laboratory Medicine Services, Sydney, (PaLMS).

For each issue raised, I explain:

  • What Went Wrong
  • Why it Matters

Notes for Charts and Tables

Where a chart is shown, you can view a larger chart in a new window by selecting the link shown above the chart.

Where there is a link to a table, above a chart, you can view the complete Excel table in a new window.

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, available on this site from Evidence.

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PaLMS Homocysteine Errors

Summary of What Went Wrong

There were very significant differences between Sullivan Nicolaides Pathology and Westmead results for the same samples.

The important points to note, about homocysteine levels, from the PaLMS Sample A and Westmead Sample A results are:

  • The maximum difference between the labs was 9.62 SD.
  • All 13 results were outside the 95% Confidence Interval.
  • All 13 of those results were also outside the 99.0% Confidence Interval.
  • 12 of those results were also outside the 99.9% Confidence Interval.

The important points to note, about homocysteine levels, from the PaLMS Sample B and Westmead Sample B results are:

  • The maximum difference between the labs was 14.18 SD.
  • 15 out of 16 results were outside the 95% Confidence Interval.
  • 14 of those results were also outside the 99.0% Confidence Interval.
  • All 14 of those results were also outside the 99.9% Confidence Interval.

Although the PaLMS results were much closer to the SNP results, there were significant differences between PaLMS and SNP. The important points to note, about homocysteine levels, from the SNP Sample B and PaLMS Sample B results are:

  • The maximum difference between the labs was 8.08 SD.
  • Eight out of 16 results were outside the 95% Confidence Interval.
  • Six of those results were also outside the 99.0% Confidence Interval.
  • Five of those results were also outside the 99.9% Confidence Interval.

I am confident that the Westmead results are correct because:

  • Westmead uses Stable Isotope Dilution Tandem Mass Spectrometry, the reference method also used by Mayo Medical Laboratories.
  • Westmead proved their reliability as a very high quality lab by producing excellent MMA results
  • Westmead is involved in an international, external quality control program (ERNDIM) for homocysteine

I am confident that the PaLMS results are incorrect because:

  • The Immunoassay method used by SNP is subject to interferences
  • Immunoassay control ranges are open to abuse, allowing for very significant errors

Why it Matters

PaLMS failed to report the existence of vitamin B12 deficiency. Because these were retrospective tests, this did not affect my decision-making during the initial investigation. The important issue here is how these errors would affect other patients.

According to experts, homocysteine is a sensitive marker of vitamin B12 deficiency. Some excellent articles on this can be found by selecting reference DA01 to DA06.

Here is a chart showing my homocysteine measured by PaLMS, compared to my homocysteine measured by Westmead:

Chart E26 Table B18

As you can see, at no time did the PaLMS homocysteine level exceed their quoted maximum level of 15 umol/L, whereas the Westmead results are frequently above, or very close to, their quoted maximum of 13.7 umol/L.

The differences between the labs produce totally different interpretations of my vitamin B12 status. According to the PaLMS results, my homocysteine was always low and did not indicate vitamin B12 deficiency. According to the Westmead results, my homocysteine level increased dangerously and clearly indicated vitamin B12 deficiency.

The worst case example was for Sample B, for 15 November 2006. PaLMS reported a homocysteine reading of 6.3 umol/L, a very low level, not supportive of a diagnosis of vitamin B12 deficiency. For the same sample, Westmead reported a result of 17.4 umol/L, strongly supporting a diagnosis of vitamin B12 deficiency.

The need for both accuracy and precision is clearly explained in an ERNDIM Report, reference AB01:

There are many excellent expert reports on the subject of homocysteine measurement accuracy and precision, including reference AE14 to AE19.

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PaLMS Homocysteine - Use of Incorrect Cut-off

Summary of What Went Wrong

PaLMS incorrectly quotes a limit of 15.0 umol/L for total homocysteine:

A homocysteine level of 15.0 umol/L is not considered safe by most experts, including authors of reference AE11 and AE12. Both of these expert groups recommend a maximum level of 12.0 umol/L.

A homocysteine level of 15.0 umol/L is not considered safe by most experts, including authors of reference AE11 and AE12. Both of these expert groups recommend a maximum level of 12.0 umol/L. The following table from Refsum et al, reference AE11 Table 6, shows the recommended maximum homocysteine levels for different patient groups:

In Australia, many processed foods, including breakfast cereals, are folate enriched, so the folate supplemented figure of 12 umol/L should be used for people aged 15-65 years..

Here is the diagnostic flowchart for homocysteine, as shown by D.A.C.H. - Liga Homocystein in reference AE12:

As you can see, a level of > 12 umol/L is considered high for a healthy population; a level > 10 umol/L is high for those patients at risk for cardiovascular disease.

The following chart from Refsum et al, reference AE11 Figure 4, shows the normal total homocysteine level compared to age:

Another expert report by Rasmussen et al, reference AF01, provides a range of age and gender-specific reference intervals. For a male aged 30 to 59 years, the recommended limit is 11.2 umol/L.

Reputable laboratories use much lower levels than the 15.0 umol/L quoted by SNP; several are listed in reference AF08 to AF22. This table lists some of these limits, in umol/L:

-
Mayo
Cleveland
Calgary
Cedars-Sinai
Sundhed
Male
<13
13.7
13.7
12.0
11.2 - 12.0
Female
<13
12.9
9.9 - 12.8
10.0
11.2 - 12.0

PALMS not alone in quoting an incorrect homocysteine cut-off; it also appears in the RCPA manual, reference AF05.

Why it Matters

Not only is a high level of homocysteine an indicator of vitamin B12 deficiency, it is also an indicator or risk factor for other diseases including:

  • depression
  • Alzheimer's disease
  • Cardiovascular disease

There are many expert reports on the association between homocysteine and disease, including reference AE11, AE12, CA21 to CA26 and CB01 to CB13. As an example, the following chart from Nygard al, reference CB04, Figure 2, shows the relationship between Mortality Ratio for patients with CAD, and total homocysteine:

Note the very significant increase in mortality ratio, as homocysteine increases from 10 umol/L to 15 umol/L.

In my case, PaLMS failed to report the existence of an actual vitamin B12 deficiency that should have been interpretable from their homocysteine results.

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PaLMS Homocysteine - Incorrect Dates in Reports

Summary of What Went Wrong

Many of the dates in the original pathology reports supplied by PaLMS were incorrect; my surname was also incorrectly spelled in one place on each page, although it was correct in another part of the page.

Here is an example of some incorrect collection dates:

There were no samples collected on 1 November or 14 November.

The explanation offered to me was that the labels were difficult to read. That might have been true but, especially as PaLMS had been supplied with a list of samples, this does not excuse the use of fictitious dates in reports.

Why it Matters

Incorrect sample dates can potentially lead to very serious errors in interpretation of trends in results. In my case, the errors were so obvious that they were readily detected; this does not excuse the making of these mistakes.

This episode is, in my opinion, an example of failure of quality control, within PaLMS.

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PaLMS Homocysteine - Refusal to Release Results

Summary of What Went Wrong

Before I discovered the loss of all of the first series of samples, I had decided to commence a second Series 1a. Unlike the first series, which had required 39 collections of my blood over a 13 month period, this new series would require only three collections over consecutive days.

The purpose of the second series was to have several labs test three pairs of samples for total homocysteine and compare the differences between labs, for these fresh samples, with the differences for the first series. The results would possibly explain the very significant differences between the labs, and the differences between the A and B samples, as observed in the first series results.

I arranged with QML Pathology in Brisbane to collect two samples each day for three days, test them all in a single batch, then send them to PaLMS in Sydney. Dr KC at Westmead and Dr JW at RPAH also agreed to test this second series for me.

The samples were collected on 15, 16 and 17 January 2007; they were tested by QML Pathology and sent, via World Courier, to PaLMS on 18 January.

I received a reply from Dr RB, Divisional Manager, Clinical Biochemistry; he was the pathologist who I had originally contacted at the PaLMS lab. In his Email, he stated that he had asked that my results not be released, and raised concerns about what I was intending to do with them:

And here is my response to his claim for an assurance that I would not identify his lab:

I never received the results of the Series 1a tests from PaLMS.

Why it Matters

The so-called compromise would give Dr B the right to veto anything that I wish to publish concerning their results for my samples. Of course, unless I am prepared to make no criticism of anyone, it is impossible for me to give such an undertaking.

The results of the second series were needed to allow me to plan further homocysteine testing of the first series, and to plan a third series. Because I did not have the results from PaLMS, I was forced to abandon the second series, and bring forward the third series. I lost all the value of the time, effort and money spent so far on the second series.

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