Sorry that should say, "taking a sample from a dip arm would be contraindicated too." Ooops. Freudian slip.
David Ryder, Point of Care Testing Coordinator
University Hospitals of Morecambe Bay NHS Foundation Trust
Furness General Hospital
Dalton Lane
Barrow-in-Furness, Cumbria, LA14 4LF
External: 01229 491171 | Extension: 51171 | Mobile: 07580 818900
-----Original Message-----
From: ACB Point-of-Care Testing [mailto:[log in to unmask]] On Behalf Of Ryder David (UHMB)
Sent: 04 July 2018 16:28
To: [log in to unmask]
Subject: Re: ACB-POCT Digest - 3 Jul 2018 (#2018-84)
Hi John,
Your calculations are interesting, but the assumptions aren't necessarily true. Raised sodiums due to samples being taken from a drip arm are a case in point (not a great argument I admit, but it sort of illustrates how the assumptions could regularly fall down). Taking the sample from the drip arm wouldn't be contraindicated too, but you can’t discount that it might happen and the vit c would have a counter intuitive effect on the result, in that the glucose reading would go up.
We do state that once the infusion is finished the levels of vit C should be low enough for POCT testing to continue. As this is what we were advised by Roche.
Roche state in the IFU that anything > 0.17mmol/L will interfere. From your calculations, the levels during infusion could be 2 times the limit of interference.
Interference limit: 0.17 mmol/l = 3mg/dl. Transient infusion concentration: 7 mg/dl = 0.397 mmol/l
I think it's well worth the caution. Definitely worth a study. Alternatively, you could use meters that are not affected by vit C.
Kind Regards,
David Ryder, Point of Care Testing Coordinator
University Hospitals of Morecambe Bay NHS Foundation Trust
Furness General Hospital
Dalton Lane
Barrow-in-Furness, Cumbria, LA14 4LF
External: 01229 491171 | Extension: 51171 | Mobile: 07580 818900
-----Original Message-----
From: ACB Point-of-Care Testing [mailto:[log in to unmask]] On Behalf Of Shepherd, John
Sent: 04 July 2018 12:01
To: [log in to unmask]
Subject: Re: ACB-POCT Digest - 3 Jul 2018 (#2018-84)
Thanks David - I certainly agree. The reports I see relate to megadoses of vitamin C, however Pabrinex (frequently used as an IV infusion for alcoholics) contains various vitamins Bs & C. Vitamin C at 1000 mg per vial infused iv over 30 min. 33 mg per min distributed in the blood volume (5L) so potentially transient levels of around 7 mg/dL(?)
Studies indicate that prolonged oral doses of 1000 mg/day result in steady state plasma levels of around 1.5 mg/dL
Magadoses in reports are 10g every 2 days and 75g twice weekly- clearly much greater levels.
The Vit C ref interval is 0.4-1.5 mg/dL.
The renal threshold is 1mg/dL and large doses can result in values greater than 2 mg/dL
Roche state interference at levels greater than 3 mg/dL
These patients are definitely in need of glucose testing, and I don’t want to introduce unnecessary caution. It looks like a small study may be of benefit!
Best
John
Mr John Shepherd FRCPath | Consultant in Clinical Biochemistry
Blood Sciences, Pathology Dept, Hull and East Yorkshire Hospitals, Anlaby Road, HULL, HU13 2JZ
B 00 44 (0)1482 607707 (direct)
-----Original Message-----
From: ACB Point-of-Care Testing [mailto:[log in to unmask]] On Behalf Of ACB-POCT automatic digest system
Sent: 04 July 2018 00:00
To: [log in to unmask]
Subject: ACB-POCT Digest - 3 Jul 2018 (#2018-84)
There is 1 message totaling 251 lines in this issue.
Topics of the day:
1. Glucose - Vit C
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Date: Tue, 3 Jul 2018 13:38:56 +0000
From: "Ryder David (UHMB)" <[log in to unmask]>
Subject: Re: Glucose - Vit C
We currently contraindicate for vit C infusion. I don’t have a method for measuring vit C at POCT.
Last year there was a death in the US using inform II strips and the health professional didn’t realise there was a contraindication against using the meter with the vit C infusion. Can’t remember what the product was called now that was being infused.
I’m not sure how the coroner would react if you said you knew and ignored the IFU. In my personal experience it doesn’t go well for the health professional (family experience, not as health professional).
On another personal note, I have high triglycerides and I’ve often had high glucose readings with inform ii strips, when compared with the lab. Patients with high triglycerides are contraindicated too. > 20.3 mmol/l I think. (Before you ask, yes my triglycerides do get that high, even when fasting) It helps my users remember it’s an issue if I give some background. So, we tell them to avoid using the glucose meters if a patient is on TPN as you can’t guarantee that the patients triglycerides are below the magic number.
Kind Regards,
David Ryder, Point of Care Testing Coordinator
University Hospitals of Morecambe Bay NHS Foundation Trust Furness General Hospital Dalton Lane Barrow-in-Furness, Cumbria, LA14 4LF
External: 01229 491171 | Extension: 51171 | Mobile: 07580 818900
From: ACB Point-of-Care Testing [mailto:[log in to unmask]] On Behalf Of Debbie Gooseman
Sent: 29 June 2018 13:11
To: [log in to unmask]
Subject: Re: Glucose - Vit C
Hi John,
We use Abbott meters. Our SOP states IV infusion of high dose ascorbic acid as a contraindication for meter use.
It’ll be interesting to see what everybody else does.
Regards
Debbie Gooseman
POCT Coordinator
Northern Lincolnshire and Goole NHS Trust
Sent from my iPhone
On 29 Jun 2018, at 11:08, Shepherd, John <[log in to unmask]<mailto:[log in to unmask]>> wrote:
Hi
Does anyone contra-indicate POC glucose measurement when patients are on Pabrinex due to the effect of vit C on glucose dehydrogenase? Roche users in particular.
I can find case reports showing issues with mega doses, but nothing for this commonly used IV supplement.
JS
John Shepherd
Blood Sciences, Pathology Dept, Hull and East Yorkshire Hospitals, Anlaby Road, HULL, HU13 2JZ • 00 44 (0)1482 607707 (direct)
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