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 METHYLMALONIC ACID INVESTIGATION
MMA ERRORS
Summary
Laboratory Performance
Mater Pathology
Interpretation Errors

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 Mater Pathology, Brisbane (MP)

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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MP MMA - Quoted Precision is Inadequate

Summary of What Went Wrong

Mater Pathology quoted a Coefficient of Analytical Variance (CVA) of 1 SD = 0.03 umol/L for MMA, in an Email, of 23 June 2006:

I need to briefly explain why the quoted CVA is so important. The required precision for any test depends on the known within-subject biological variation (CVW). If the analytical variation (CVA) is too high, an actual significant change can be masked by analytical error; this can lead to serious misinterpretation of results.

Rasmussen et al, reference AF02, found that the day-to-day intra-individual variation for MMA was 0.031 umol/L.

According to Fraser et al, reference AB31, cited by Pfeiffer et al, reference AE13, analytical imprecision (CVA) should be less than 0.5 times the within-subject biological variation (CVW) for desirable performance, or less than 0.75 times the within-subject biological variation (CVW) for minimum performance.

This means that, for satisfactory performance, the lab would need to achieve a CVA of less than 0.016 umol/L for MMA; for minimum performance, a lab would need to achieve a CVA of less than 0.23 umol/L.

Westmead quotes a CVA of 1 SD = 0.015 umol/L for MMA, which is less than 0.5 times the CVW of 0.31 umol/L. The CVA quoted by Westmead is therefore consistent with the requirement for satisfactory performance, based on the within-subject biological variation for MMA.

Mater Pathology quoted a CVA of 1 SD = 0.30 umol/L for MMA, which is greater than 0.75 times the CVW of 0.31 umol/L. The CVA quoted by MP is therefore not even consistent with the requirement for minimum performance.

Why it Matters

If a lab cannot achieve a CVA required for even the minimum performance for MMA, their results cannot be used to diagnose or monitor vitamin B12 deficiency.

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MP MMA - Failed Own Test for Precision

Summary of What Went Wrong

Mater Pathology repeated tests on two samples, and tested another sample six times; here is an extract from his report:

The important points to note from this report are:

  • The result for the sample of 5 May changed from 0.36 umol/L to 0.27 umol/L
  • The result for the sample of 19 May changed from 0.30 umol/L to 0.40 umol/L.
  • The reported standard deviation, of 0.055 umol/L, is far higher than the 0.03 umol/L quoted.

Why it Matters

The amended result alters the apparent direction of movement of MMA level, for that period of time, from decreasing to increasing.

By failing their own test for repeatability of MMA results, Mater Pathology demonstrated that they were unable to meet the required precision to diagnose or monitor vitamin B12 deficiency.

The reported CVA, of 1 SD = 0.055 umol/L, is very significantly greater than 0.75 times the within-subject biological variation of 0.31 umol/L.

Mater Pathology therefore demonstrated that they were incapable of performing MMA analyses that meet even the minimum standard of performance.

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MP MMA - Use of Incorrect Cut-off

Summary of What Went Wrong

Until 1 January 2006, Mater Pathology quoted a limit of 1.0 umol/L for MMA; since 1 January 2006, Mater Pathology has quoted a limit of 0.5 umol/L for MMA:

The first limit is far higher than what is quoted by any other lab that I am aware of. The second limit is shared only by Women's and Children's Hospital, Adelaide (WCH).

Most laboratories quote limits between 0.34 and 0.40 umol/L, the lowest being 0.28 umol/L; several are listed in reference AF03, AF10, AF11 and AF13. This table lists some of these limits, in umol/L:

Mayo
Cleveland
Sundhed
RPH
CHW
QHPS
0.40
0.376
0.28
0.35
0.34
0.40

Holleland et al, reference DA08, reported these findings:

Why it Matters

The limit of 1.0 umol/L is so high that the test is too insensitive to detect many cases of vitamin B12 deficiency. This can be seen from the chart shown by Allen et al, reference AE01:

Allen et al

The effect of this problem was significantly worsened by the insensitivity of the analyses, causing very significant errors and uninterpretable results, as described in the next section.

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MP MMA - First Errors

Summary of What Went Wrong

Because of my suspicions about the quality of the Mater Pathology MMA analyses, I arranged for another lab, Women's and Children's Hospital, Adelaide (WCH) to re-test four samples.

The results from WCH confirmed that there were very significant errors in the results from Mater Pathology, as shown in the following table:

Sample Date MP Result (umol/L) WCH result (umol/L)
28 Oct 2005 1.2 1.43
2 Nov 2005 2.0 1.79
11 Nov 2005 1.2 0.22
25 Nov 2005 1.0 0.22

Here is a chart of the MMA results from MP and WCH:

Chart C13 Table C8

Mater Pathology repeated their analysis of the sample for 30 December 2005 The newly reported MMA level was 0.21 umol/L, very significantly different to their original result of 0.8 umol/L for the same sample. Here are the two results for the same sample:

In their second report of 30 December, Mater Pathology included the comments:

In what way did Mater Pathology improve on the method? Stabler et al, reference AE02, first described the method for assay of MMA using GC/MS in 1986.

Mater Pathology improved the quality of their results, until they deteriorated again in May 2006.

Why it Matters

The the two labs give totally different interpretations of my cellular vitamin B12 status, and the effect of taking the oral B12 supplement..

The WCH result shows a very distinct fall in MMA level from well above all of the cut-off levels, to well below the cut-offs after I commenced oral B12 treatment. This satisfies the criteria for diagnosis of vitamin B12 deficiency, as defined by many experts including Bolann et al, reference DA08:

Although the MP results show some fall in MMA level, following my oral B12 treatment, they fail to detect the fall below any of the cut-off levels.

These very significant errors are, in my opinion, examples of failure of quality control within Mater Pathology.

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MP MMA - Continuing Errors

Summary of what went wrong

There were very significant differences between Mater Pathology results for identical samples, and between Mater Pathology results and Westmead results for the same samples.

The important points to note, about MMA levels for Sample A and Sample B, from the MP results are:

  • The maximum difference between Sample A and Sample B, for any pair was 12.43 SD.
  • Five results out of nine pairs were outside the 95% Confidence Interval.
  • All five of those results were also outside the 99.0% Confidence Interval.
  • Three of those results were outside the 99.9% Confidence Interval.

The important points to note, about MMA levels, from the MP Sample A and Westmead Sample Mean results are:

  • The maximum difference between the labs was 15.63 SD.
  • 14 results out of 22 were outside the 95% Confidence Interval.
  • 10 of those results were also outside the 99.0% Confidence Interval.
  • Eight of those results were also outside the 99.9% Confidence Interval.

I am confident that the Westmead results are correct because:

  • For each sample pair, there was no significant difference between the two samples; this is the expected result because Sample A should be identical to Sample B.
  • There is a consistent increasing trend in the MMA level, as would be expected during the onset of vitamin B12 deficiency.
  • Westmead uses Stable Isotope Dilution Tandem Mass Spectrometry, the reference method also used by Mayo Medical Laboratories.
  • Westmead quotes a CVA of 0.015 umol/L for MMA, consistent with satisfactory performance, for the known CVW of 0.31 umol/L.

I am confident that the MP results are incorrect because:

  • For five sample pairs, there was a significant difference between the two samples; this is NOT the expected result because Sample A should be identical to Sample B.
  • There is no consistent increasing trend in the MMA level; such a trend would be expected
  • MP quoted a CVA of 0.30 umol/L, which is not even consistent with minimum performance.
  • In their own test, MP actually achieved a CVA of 0.055 umol/L, which is not even consistent with minimum performance.

Why it Matters

Mater Pathology failed to report the onset of an actual vitamin B12 deficiency.

Westmead reported my MMA levels increasing during 2006, after I ceased taking oral B12. Here is a chart showing how Mater Pathology reported my MMA levels, compared to Westmead, for the group A samples:

Chart D13 Table B2

The Westmead results show a consistently increasing MMA level, exceeding the Westmead cut-off between 24 February and 5 June 2006, then remaining above it. This means that I was consistently vitamin B12 deficient, by the very latest, after 5 June 2006.

The Mater Pathology Pathology results show that, until May 2006, my MMA level increased reasonably consistently, remaining well below the cut-offs.. After 19 May, there were increasing errors in the MMA level reported by Mater Pathology. The MP results incorrectly show the MMA level erratically varying between well above the cut-off, and well below it.

Because of these false variations, and an absence of the actual consistently increasing trend of the MMA level, Mater Pathology failed to report the onset of vitamin B12 deficiency.

These very significant errors are, in my opinion, examples of failure of quality control within Mater Pathology.

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MP MMA - Ignored Request for Re-testing

Summary of What Went Wrong

I sent an Email to Mater Pathology on 23 May, asking them to repeat three of the MMA analyses at my expense. After receiving no response, I sent another Email on 22 June. Mater Pathology responded to that message but did not re-test the samples. The samples that I had asked to be re-tested had not been kept, having apparently been destroyed since my Email of 23 May.

Why it Matters

The failure to re-test the samples, and destruction of the samples, prevented me from determining the cause of the observed inconsistencies in results at that time.

As stated in a previous section, because of these false variations, and an absence of the actual consistently increasing trend of the MMA level, Mater Pathology failed to report the onset of vitamin B12 deficiency.

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MP MMA - Delays

Summary of What Went Wrong

The important points to note, about timeliness for Mater Pathology were:

  • 11 of the 27 group A samples took more than seven days to process.
  • Of those, five samples took more than 14 days to process.
  • Of those, two samples took more than 21 days to process.
  • Of those, one sample took 35 days to process.
  • Because of inadequate records, it is not possible to know the processing time for the B samples.

When I asked about the reasons for the lengthy delays, Mater Pathology told me that they:

“ran out of Ethyl Acetate because (name deleted) forgot to order it before he went away and they did not realize it until they went to use it.”

Why it Matters

While monitoring my cellular vitamin B12 status, it was important to receive results within a reasonable time. Because of the risk of permanent nerve damage, it was necessary to avoid entering a B12 deficient state.

These delays, caused by failure to order a reagent are, in my opinion, an example of failure of quality control within Mater Pathology.

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MP MMA - Errors in Sample Documentation

Summary of What Went Wrong

Mater Pathology supplied samples to Westmead with incorrect sample dates in the documentation:

Table D1
Actual Collection Date
Date in Documentation
27 January 2006
27 October 2006
28 August 2006
9 October 2006
18 September 2006
19 September 2006
25 September 2006
21 September 2006
9 October 2006
10 October 2006

This caused erroneous dates in the Westmead reports. For example, In their report for the group A sample of 9 October, Westmead noted:

There was no sample taken on 10 Oct 2006; the date on the documentation supplied by Mater Pathology did not match the label on the sample.

Why it Matters

Incorrect sample dates can potentially lead to very serious errors in interpretation of trends in results.

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

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MP MMA - Deliberate Destruction of Samples

Summary of What Went Wrong

On 7 November 2006, Mater Pathology told me that they would no longer co-operate with my MMA testing and would destroy my samples.

On 7 November, I sent an Email to Mater Pathology, explaining why they should not destroy the samples, and instead allow me to complete the test series. I followed up with another email, offering to reduce the number of tests, on the same day.

After receiving no response to my messages of 7 November, I sent another Email to Mater Pathology on 8 November. In that message, I assured them that the test program was almost completed and said:

Mater Pathology responded with an Email on 9 November, in which he said:

I was alarmed at the possibility that Mater Pathology would actually destroy samples that I needed to have re-tested by another lab. On 20 November 2006 I sent an Email to Mater Pathology, offering to pay the full cost for MP to store my samples and send them out to Westmead. In that Email, I said:

Mater Pathology replied on the same day with an Email in which he insisted that my samples would be destroyed:

I sent my final Email to Mater Pathology on 27 November 2006, in which I said:

I then received a letter from the lawyer for Mater Pathology, in which he says:

You will see that the letter is a draft, containing some significant changes.

I did not respond to the letter from Mater Pathology.

Mater Pathology did not send my last four samples to Westmead; as far as I am aware, they were destroyed.

Why it Matters

The samples were actually required for further testing by other labs. The destruction of the samples prevented further testing, as follows:

  • MMA results from QHPS and CHW, so reducing the number of Sample A and Sample B pairs that were analysed.
  • Total Homocysteine results from CHW and PaLMS, so reducing the number of Sample A and Sample B pairs that were analysed.
  • Serum Vitamin B12, so preventing investigation of the anomaly in the reported SNP results

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MP MMA - Incomplete Reports

Summary of What Went Wrong

On 6 December 2006, I sent an Email to Mater Pathology , seeking a copy of my pathology reports in accordance with the Privacy Act.

There were problems with the handling of even this simple request:

  • Mater Pathology, initially insisted that I had to send a copy of a photo ID, witnessed by a JP to prove my identity; this was claimed to be to protect my privacy.
  • Although we agree that they would send the reports by registered Post, they were sent express post, contrary to the claimed concerns for my privacy
  • Eight of the 53 pages of the reports contained everything except the results; most were eventually replaced.

Why it Matters

This episode is, in my opinion, an example of a failure of quality control, within Mater Pathology.

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MP MMA - Legal Threat

Summary of What Went Wrong

As part of my investigation of the significant differences between labs for my homocysteine results, I decided to consider the possibility that sample-mishandling could explain some of the anomalies. This was prompted by the report from Westmead that the three samples received directly from Sullivan Nicolaides were frozen in SST tubes.

On 16 February 2007, I sent an Email to Mater Pathology, asking about the condition of the samples received by MP:

I should point out here that neither QHPS nor Mater Pathology were asked to analyse my samples for homocysteine; I was really checking up on sample handling by Sullivan Nicolaides Pathology. The MMA results could not have been affected by sample handling because Westmead proved that the samples within each pair were still identical, in MMA levels, when they received them.

In a letter dated 7 March 2007, Mater Pathology responded to my investigation into the anomalies in results:

Here is what Mr Mater Pathology said in his response to my questions:

I have not made any further contact with Mater Pathology since then.

Why it Matters

Why did Mater Pathology threaten me with legal action?

Compare the response to my complaints, with the public image being promoted by Mater on their web site:

Mater Mission Statement

In the spirit of the Sisters of Mercy, Mater Hospitals offer compassionate service to the sick and needy, promote an holistic approach to healthcare in response to changing community needs and foster high standards in health-related education and research.

Following the example of Christ the Healer, we commit ourselves to offering these services to all without discrimination.

Our Values

Mater staff are dedicated to providing highest quality healthcare services, through a sincere commitment to the Mater's core values of Mercy, Dignity, Care, Commitment and Quality. Using these values as a guide for our interactions with our patients and their families, each other and our business partners, Mater staff promote the professionalism and care that has been a part of the Mater since its beginnings.

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