[Multibilly]

Why you may still need to test your urine

by Multibilly on Wed Jul 18, 2018 8:21 pm

Interesting press release that asserts the following:

“When you test the serum, we suggest you also test the urine whenever you suspect that somebody has a tumor of the plasma cells,” says Dr. Gurmukh Singh, vice chair of clinical affairs for the Department of Pathology at the Medical College of Georgia at Augusta University.

The decades-old urine test is still used by pathologists and requested by physicians, but its use declined when the serum free light chain assay became available about a dozen years ago, Singh says, and some physicians may now think that the urine test is redundant. The different tests look in the serum or urine for signs of the abnormal antibody, and to see if the usual ratio is off for two types of a portion of the antibody, called light chains.

The new study, published in the Journal of Clinical Medicine Research, indicates that if the multiple myeloma is associated with the type called the lambda light chain, there is about a 25 percent chance the problem will not be detected by the serum test for free light chains, the investigators report from their retrospective review of tests on 175 patients.

“If you have a lambda chain-associated lesion and you don’t do a urine study, just rely on the serum free light chain assay, about 1 out of 4 times, the assay will tell you that you don’t have anything when you actually do,” says Dr. Won Sok Lee, fourth-year pathology resident at MCG and AU Health and the study’s coauthor.

Link to full press release:

"Looking at the urine and blood may be best in diagnosing myeloma," Augusta University press release, July 13, 2018 (full text)

Reference and links to original research article:

Lee, WS, and Singh, G, "Serum Free Light Chains in Neoplastic Monoclonal Gammopathies: Relative Under-Detection of Lambda Dominant Kappa/Lambda Ratio, and Underproduction of Free Lambda Light Chains, as Compared to Kappa Light Chains, in Patients With Neoplastic Monoclonal Gammopathies," Journal of Clinical Medical Research, June 4, 2018 (abstract; full text of article [HTML]; full text of article [PDF]; full text of article [PubMed Central];)

Abstract:

Background - Quantitative evaluation of serum free light chains is recommended for the work up of monoclonal gammopathies. Immunoglobulin light chains are generally produced in excess of heavy chains. In patients with monoclonal gammopathy, κ/λ ratio is abnormal less frequently with lambda chain lesions. This study was undertaken to ascertain if the levels of overproduction of the two light chain types and their detection rates are different in patients with neoplastic monoclonal gammopathies.

Methods - Results of serum protein electrophoresis (SPEP), serum protein immunofixation electrophoresis (SIFE), urine protein electrophoresis (UPEP), urine protein immunofixation electrophoresis (UIFE), and serum free light chain assay (SFLCA) in patients with monoclonal gammopathies were examined retrospectively.

Results - The κ/λ ratios were appropriately abnormal more often in kappa chain lesions. Ratios of κ/λ were normal in about 25% of patients with lambda chain lesions in whom free homogenous lambda light chains were detectable in urine. An illustrative case suggests underproduction of free lambda light chains, in some instances.

Conclusions - The lower prevalence of lambda dominant κ/λ ratio in lesions with lambda light chains is estimated to be due to relative under-detection of lambda dominant κ/λ ratio in about 25% of the patients and because lambda chains are not produced in as much excess of heavy chains as are kappa chains, in about 5% of the patients. The results question the medical necessity and clinical usefulness of the serum free light chain assay. UPEP/UIFE is under-utilized.

[Mike F]

Re: Why you may still need to test your urine

by Mike F on Thu Jul 19, 2018 10:38 am

Very interesting! Like many others, I suspect, I haven't had my urine checked since I was diagnosed six years ago.

[Multibilly]

Re: Why you may still need to test your urine

by Multibilly on Thu Jul 19, 2018 11:14 am

I think this is interesting as there have been a few posts on this forum over the years where a urine test will pick up an M-spike, but one will have a completely normal serum free light chain numbers and serum immunofixation results.

Last edited by Multibilly on Thu Jul 19, 2018 12:58 pm, edited 1 time in total.

[Nancy Shamanna]

Re: Why you may still need to test your urine

by Nancy Shamanna on Thu Jul 19, 2018 11:44 am

After some discussions on this Forum a few years ago, I asked my oncologist to requisition a 24-hour urine test! We both agreed that probably the serum free light chain tests were enough in my case, and they were, but it was nice that he cooperated with my request. I had them done as part of my initial diagnosis and during the first year of treatments also. When I was first diagnosed I don't recall that the serum free light chain tests were in use here yet.

[goldmine848]

Re: Why you may still need to test your urine

by goldmine848 on Thu Jul 19, 2018 6:01 pm

This is interesting, thanks for the article. I looked at the research report and it was not clear whether they used spot urine or 24-hour urine collection, but it seems like it was spot urine. Am I correct on this?

[Multibilly]

Re: Why you may still need to test your urine

by Multibilly on Thu Jul 19, 2018 7:48 pm

Great question Andrew. Reading through the article, it's not clear to me which of those two tests they used. I therefore reached out to one of the paper's authors to have them clarify which test they used. We will see if he responds.

[Multibilly]

Re: Why you may still need to test your urine

by Multibilly on Fri Jul 20, 2018 7:51 am

Andrew,

One of the authors was kind enough to get back to me. Interestingly, the research was indeed based all on spot urine tests.

[goldmine848]

Re: Why you may still need to test your urine

by goldmine848 on Fri Jul 20, 2018 8:03 am

That's what I thought, thanks for checking. I know that there are differences of opinion among doctors on the need for the 24-hour test after initial diagnosis. I have had only one 24-hour test, but I do get the spot tests with each blood draw. I saw a new doctor in June and he thought it would be a good idea to do a 24-hour collection. It's a pain to do, but I will do it.

[Mike F]

Re: Why you may still need to test your urine

by Mike F on Fri Jul 20, 2018 10:33 am

Nice to know that the spot test is likely good enough. As Andrew said, the 24 hour thing is a pain. (Not a terribly bad one on the myeloma pain scale, but still ...)