Hi
We can do a serum MMA mass spec assay. It's not currently ukas accredited and running it weekly as a research assay in final stages of validation.
Cheers
Craig
Dept Clinical Chemistry
Birmingham Heartlands Hospital
Sent from my iPhone
On 21 Jun 2016, at 15:32, Simon Olpin <[log in to unmask]<mailto:[log in to unmask]>> wrote:
Dear Clodagh,
we offer urine MMA/creatinine for £72. This is a useful marker in our experience and we do identify "deficient" patients in both the adult and more specifically the neonatal population not too infrequently. Most patients do respond biochemically to IM B12 within days. In infants often of vegan /vegetarian mothers, there is often prolonged jaundice & failure to thrive (sometimes more serious developmental delay) and in these there is generally a rapid clinical response to B12. Total homocysteine is sometimes raised in these patients with increased MMA but in my experience it is not as sensitive a marker although that may depend on the population under investigation. We will comment on B12 of <350 suggesting that this does not exclude B12 deficiency (particularly where there is clinical concern) & we suggest urine MMA as follow up. The haematological picture too can be relatively normal in some patients where there is evidence of peripheral neuropathy but raised MMA in urine.
Best wishes
Simon
Dr Simon Olpin PhD CSci FRCPath
Consultant Clinical Scientist in Inherited Metabolic Disease
Department of Clinical Chemistry
Sheffield Children's Hospital
Western Bank
Sheffield S10 2TH
+ 44 (0)114 2717267
>>> "Loughrey, Clodagh" <[log in to unmask]<mailto:[log in to unmask]>> 21/06/2016 14:52 >>>
Thanks, Simon, there does seem to be a consensus that plasma B12 in the low normal range (< 350 pcg/L) was suggested) may not be entirely reliable and in that scenario, with symptoms, a plasma THcys would be a useful surrogate marker of intracellular B12 status, < 15 mmol/L putting it to bed. Would you recommend urine MMA as a more reliable marker than THCys, or save it for any ≥ 15mmol/L? Bearing in mind accessibility / cost.
C.
From: Simon Olpin [mailto:[log in to unmask]]
Sent: 21 June 2016 14:44
To: Loughrey, Clodagh; [log in to unmask]<mailto:[log in to unmask]>
Subject: Re: "B12 deficiency"
Hi Clodagh,
there is evidence to suggest that the B12 assays particularly towards the lower end may not accurately reflect tissue B12 status. Urine MMA is now generally considered to be a more sensitive marker of tissue B12 status than plasma B12. I would therefore be inclined to use urine MMA as the more reliable marker. Total plasma homocysteine may also be a sensitive marker for tissue B12 status in some patients although folate & riboflavin status also influence total homocysteine concentration.
Best wishes
Simon
Dr Simon Olpin PhD CSci FRCPath
Consultant Clinical Scientist in Inherited Metabolic Disease
Department of Clinical Chemistry
Sheffield Children's Hospital
Western Bank
Sheffield S10 2TH
+ 44 (0)114 2717267
>>> "Loughrey, Clodagh" <[log in to unmask]<mailto:[log in to unmask]>> 21/06/2016 12:26 >>>
Anyone encountered the situation below yet? This question is from one of our haematologists:
“We have had a couple of young female patients referred through our department recently who are of the unshakeable opinion that they require high doses of parenteral B12 (in one case she is self-administering on alternate days) to alleviate/prevent a variety of symptoms. I believe there are online forums specific to this issue. They are not reassured by the B12 assay and have been requesting additional assays/genetic tests. Unfortunately the BSCH guideline on the subject of B12 leaves the duration rather open-ended for patients with neuropathy…although probably not the case here. Have you any experience of this? Understandably, their respective GPs are requesting advice.”
I am presuming they are looking for total homocysteine, urine MMA, IF antibodies, holotranscobalamin and / or cobalamin defect genetic testing. I have advised that if the B12 (and Hb/ MCV) is within the reference range, there are no clinical features that could be in any way attributable to B12 deficiency, and there is no overt reason for them to have B12 deficiency (diet / alcohol / SB pathology etc), I don’t think any further laboratory testing is warranted. Particularly if they have already been receiving high doses of parenteral B12…
But I’m interested to know if others have encountered this and how you have advised.
Bw
Clodagh
CM Loughrey MD MRCP FRCPath MA
Consultant Chemical Pathologist
Clinical Director Laboratories
Belfast HSC Trust
Tel: 0044 28 950-48823
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