Nick Miller wrote:
>In reply to Trevor Gray's enquiry, the test you are interested in is
>urinary sulphite, which is not a normal component of urine.
>Sulphite, either ingested as a food preservative or endogenously
>formed, is usually oxidised to sulphate prior to its excretion by the
>action of sulphite oxidase, a molybdenum-dependent enzyme.
>Sulphite thus appears in the urine in a) sulphite oxidase deficiency
>(extremely rare) b) Mb deficiency (not so rare as you might think)
>c) asthmatic hypersensitivity after the ingestion of sulpite-preserved
>foods. In Mb deficiency (b) the disappearance of sulphite from the
>urine after Mb administration is used as a functional test for Mb
>deficiency.
Prof Bo Sörbo (died 1990) was very interested in sulfur metabolism
and this included also sulfur dioxide and sulfite. In water these
components are in equilibrium.
Sulfur dioxide and sulfites react with free -SH groups of cystein
in proteins and, when the protein is degraded, this eventually
yields thiosulfate, which will be excreted in the urine.
Under prof Sörbo I developed a method for thiosulfate in urine
(Scand J Clin Lab Invest 1978;38:521-7) and we also found (unpubl)
that this method could reveal occupational exposure to sulfur dioxide.
Probably the reaction of sulfite with proteins is rather slow and,
if the ingestion or metabolic production of sulfite is rapid, a great
deal will escape as sulfite in the urine.
However, the excretion of thiosulfate should be a good indicator of
a long-term exposure to sulfur dioxide and/or sulfite(s).
If known at that time, prof Sörbo should have mentionend any connection
with schizophrenia, but this may be a recent finding. Anyhow, measurement
of thiosulfate in urine might be of interest in those cases.
Best wishes
Mr Sten Öhman, PhD
[log in to unmask]
-----------------------------------------------------
From: Mr Sten Öhman, PhD
Postal address: p.o. Box 133, S-590 70 Ljungsbro, Sweden
E-Mail address: [log in to unmask]
Phone: int: +46 13 219020, nat: 013-219020
Fax: int: +46 13 219021, nat: 013-219021
Personal home page: http://hem1.passagen.se/stoh7971/
Company home page: http://www.elfinilab.se/
------------------------------------------------------
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
|