BSH2020-EP-112 The use of urine Bence-Jones protein testing in the investigation of a new paraprotein – a DGH perspective
Aggarwal, Asha Johny, Asha
Aggarwal, Asha
Johny, Asha
Glos Author
Date
2020-04-27
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Abstract
Current BCSH guidelines recommend that following the detection of a new paraprotein, an early morning urine sample is tested for the presence of a Bence-Jones protein (BJP). If this result is positive or testing is not possible, then it is recommended that serum-free light chains (SFLC) be tested.
In our trust, when a new paraprotein is found, a flag or alert is placed on the result to the patient's GP or ward team requesting early morning urine be sent for testing to the laboratory. It was noted that many of these urine tests were never sent. It was felt that this guidance was difficult to enact and follow at our hospital trust, a large BCSH Level 3 DGH, and a project to assess this was devised.
We retrospectively audited 51 new paraprotein results, detected over a period of 2 weeks from 24 June 2019 to 11 July 2019. Of these new paraproteins, 35 were on blood tests sent from general practice, 15 from the hospital wards and two from haematology. In all but two cases, a urine BJP test was suggested with the results.
Of the 49 samples requested, 21 urine BJP tests were sent to the laboratory. Of these 21, none were positive for a paraprotein or light chains. Six patients had a SFLC sent, of which five were on haematology advice. Two patients of the 51 patients that we know of have a diagnosis of multiple myeloma.
We felt it would be useful to know what proportion of urine BJP samples received were positive across a larger sample size. Data from the laboratory have shown that, on average, 300 urine BJP tests are processed per month. Of these, around 55 will lead to the process of immunofixation. This will be followed up in more detail.
There are several reasons why the urine tests may not be sent. It involves hassle, particularly in the community, for the GP and the patient. In addition, some urine samples may be sent in the wrong container or for the wrong test and were therefore discarded.
The best way of rectifying this is difficult, particularly in a DGH setting. It is not possible for laboratory staff to chase urine tests with the GPs or the wards, or indeed to specifically request SFLC on samples that are not followed up with the recommended urine BJP test.
A more consistent approach would be to send every sample with a new paraprotein for a SFLC automatically. However, in our trust, SFLC is not done on site, and is £10 more expensive than a urine BJP test. In addition to the monetary cost, there is labour involved for the laboratory staff in packaging and sending away the SFLC to the regional centre and processing the results when they come back.
The cost of sending every sample for SFLC rather than doing urine BJP tests will be more expensive, but reduces the risk of missing patients with a diagnosis of light chain myeloma. This is a currently a significant risk, given that 15% of patients with myeloma fall in to this group.
In summary, we have followed the BSH guidelines for the investigation of a new paraprotein by requesting the appropriate tests. The testing of early morning urine for a Bence-Jones protein has a very low uptake. This may result in missing patients with light-chain myeloma. However, the alternatives to urine BJP testing are more expensive and labour-intensive. From our perspective, this is a challenge. We would be interested to know what other DGH's recommend in terms of deviations from the BSH guideline for the investigation of a new paraprotein.
Citation
Aggarwal, A., & Johny, A. (2020). The use of urine Bence-Jones protein testing in the investigation of a new paraprotein – a DGH perspective. British Journal of Haematology, 189(S1). https://doi.org/10.1111/bjh.16783