Keith,

can I suggest you have a look at a letter we published in Clin Chem.

AC Deacon, WA Bartlett

Interference by acetic acid in urinary free 5HIAA determination. Clin Chem
1982;28:250-251.

regards

Bill


Dr WA Bartlett
Consultant Clinical Scientist
Clinical Biochemistry
Birmingham Heartlands Hospital
Birmingham B9 5SS

Tel. No. 0121 766 6611 Ext 5461.
Mobile 0374 103338


-----Original Message-----
From: [log in to unmask] [mailto:[log in to unmask]]
Sent: 21 January 2000 12:09
To: [log in to unmask]
Subject: Re: 5HIAA


Given the many problems associated with 24 hour urine collections
and the debate regarding the stability of 5HIAA in urine, we have
been looking at measuring HIAA in plasma by HPLC. Our initial
studies show that HIAA is very stable in plasma for at least 1 week
at 4C and no preservatives are required (unlike sertonin assays).
Although levels of 5HIAA are much lower in plasma than urine
(nanomolar v micromolar). There is a much greater fold increase in
plasma HIAA compared with 24 hour urine excretion above their
respective reference ranges in patients with carcinoid.

Another problem with urine collections is avoiding potential
serotonin containg foods before and during the urine collection.
With a plasma sample it is only necessary to avoid these foods for
at least 8 hours prior to blood collection or preferably take a fasting
blood sample. Foods such as bananas, walnuts, pineapples were
shown to increase plasma 5HIAA by up to 10 fold 2 hours post
ingestion.

A search of the literature has shown some interest in plasma HIAA
in psychiatric illness but very little in carcinoid disease/ syndrome.
Has anybody had any experience with the plasma assay? We
would also be grateful for any samples to help us with further
investigations.

Tim Degg
Keith Allen
Clinical Biochemistry, Leeds Teaching Hospitals, UK


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