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Scand J Clin Lab Invest. 2015 Nov;75(7):610-4. doi: 10.3109/00365513.2015.1066847. Epub 2015 Jul 25.

A novel bedside diagnostic test for methanol poisoning using dry chemistry for formate.

Author information

1
a The Norwegian CBRNe Centre of Medicine, Department of Acute Medicine , Oslo University Hospital , Ullevaal , Norway.

Abstract

BACKGROUND:

The standard diagnostic approach to methanol poisoning is chromatographic measurement of methanol on centrally placed stationary equipment. Methanol poisoning in places where such equipment is unavailable is thus often not diagnosed. Methanol is metabolized to a toxic metabolite, formate; the presence of this compound indicates methanol poisoning. We have developed an enzymatic test for formate and modified it into a portable dry chemistry system that could be used anywhere.

METHODS:

The method consists of two enzymatic steps: Formation of NADH from NAD by formate dehydrogenase, and subsequent use of NADH as a reductant of a tetrazolium into a formazan dye that can be quantified photometrically or visually.

RESULTS:

The photometer gave a good correlation of R(2) = 0.9893 in serum and R(2) = 0.9949 in whole blood, showing an instrumental detection limit of less than 1 mM (4.5 mg/dL). The visual readings showed a correlation of R(2) = 0.8966. Users experienced some difficulty in separating the negative control from the low positives.

CONCLUSIONS:

We have documented the feasibility of an affordable formate strip test for bedside diagnosis of methanol poisoning and for screening of metabolic acidosis of unknown origin. Visual reading is possible, but a reader will improve reliability at lower levels of formate. Future studies are necessary to study the sensitivity and specificity towards other causes of metabolic acidosis and other acids present in human blood.

KEYWORDS:

Methanol poisoning; acidosis; bedside testing; diagnosis; formate dehydrogenase; formic acid; point-of-care technology

PMID:
26203958
DOI:
10.3109/00365513.2015.1066847
[Indexed for MEDLINE]

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