On Fri, 17 Jun 2005 10:50:58 +0100, Peter Stromberg
<[log in to unmask]> wrote:
>A 58 year-old hypertensive man has a mildly increased dopamine excretion
of 3800 nmol/24 hours ( 0 - 3300 ) noradrenaline and adrenaline excretion
being normal. For his hypertension he is currently on candesartan,
doxazosin, frusemide and moxonadine.I believe he is on no other medication.
What is the significance of this raised dopamine and are any of these drugs
assocoated with raised dopamine excretions?
>
>------ACB discussion List Information--------
>This is an open discussion list for the academic and clinical
>community working in clinical biochemistry.
>Please note, archived messages are public and can be viewed
>via the internet. Views expressed are those of the individual and
>they are responsible for all message content.
>
>ACB Web Site
>http://www.acb.org.uk
>List Archives
>http://www.jiscmail.ac.uk/lists/ACB-CLIN-CHEM-GEN.html
>List Instructions (How to leave etc.)
>http://www.jiscmail.ac.uk/
Peter,
the frusemide may well be the cause of increased dopamine in your patient.
See the following reference indicating increased urinary dopamine excretion
occurs following frusemide infusion.
Clin Sci (Lond). 1987 Aug;73(2):151-7. Jeffrey et al.
Dopamine production and metabolsim in the kidney is affected by a host of
factors. The effects of the dopamine sulphatase/sulfokinase on free
diopamine shuttle needs to be considered as well as the production from
decarboxylation of DOPA in the renal tubules. Increased delvery of DOPA to
the kidney as as a result of increased filtration follwoing increased
sympathic activity, or alteration of the normal catecholamine economy as a
result of treatment with drugs acting at the suympatheic neuro effector
cell junctions that favour increased overspil of catecholamines and there
precursors are all possibilites that need to be considered.
Experimental data have demonstrated (Jacobs MC et al J Hypertens
1995;12:1837-41) that Doxazosin can cause an increase in catecholamine
spillover in essential hypertension. Plasma noradrenaline has been shown to
rise in patients treated for 6 weeks with Doxazosin (Wilner et al Am J
Cardiol 1987;82g-86g). This is also true of other alpha blockers (e.g.
prazosin and bunazosin) have been shown to raise plasma catecholamines.
Clearly this will affect urinary output of catecholamines to reflect
increased circulating catecholamine, but I have not been able to ascertain
the magnitude of the effect in any published study.
Bottom line is that the drugs are a possible source of increased dopamine
in your patient. Need to confirm by removal of the putative offenders from
the treatment regime.
Regards
Bill
------ACB discussion List Information--------
This is an open discussion list for the academic and clinical
community working in clinical biochemistry.
Please note, archived messages are public and can be viewed
via the internet. Views expressed are those of the individual and
they are responsible for all message content.
ACB Web Site
http://www.acb.org.uk
List Archives
http://www.jiscmail.ac.uk/lists/ACB-CLIN-CHEM-GEN.html
List Instructions (How to leave etc.)
http://www.jiscmail.ac.uk/
|