We like, Cyril Weinkove, also see occasional adult cases with isolated
elevations of urinary free dopamine. If the usual drug effects
interferences/therapies are excluded as a cause of elevation then there are
a number of more interesting possibilites. The fact that some of the loop
diuretics can cause increased dopamine output is often overlooked.
We have seen elevated free dopamines associated with late pregnancy. These
get the obstetricians jumping, given the morbidity associated with phaeo and
pregnancy. Mother and babies are usually OK on screening post partum. There
is some evidence that these particular case may represent the extremes of a
higher reference interval for urinary free dopamine associated late
pregnancy and we are pursuing this at present. One possible source of
increased output is the desulphation of dopamine sulphate by urinary
sulphatase. It has always been stated that most of the free dopamine arises
from decarboxylation of DOPA by the renal tubules. In fact there is
considerably more dopamine present in the urine in the form of sulphate
which may act as substrate for an active sulphotransferase/sulphatase
shuttle in the kidney. This system may be involved in natureisis and also
protect the kidney from free radical damage arising from free dopamine
metabolism within the kidney. Also concentrations of dopamine sulphate in
plasma are significantly higher than those of free dopamine and change in
response to pathology (e.g. heart failure).
Significant sulphatase activity is found in fresh urine and
interestingly much higher levels are found in the urine of diabetics. The
possibilities for isolated elevation of free dopamine could include an
increase in urinary sulphatase activity in the bladder converting dopamine
sulphate to free dopamine, increase in the concentrations of dopamine
sulphate in some pathological states produce more substrate for the
sulphatase in urine, or an imbalance in the renal sulphate shuttle. I'm
suggesting that this happens in vivo since collection of urine into acid
destroys the sulphatase activity.
I have also seen reports of isolated free dopamine elevation in patients
with cardiac arrhythmia.
I hope these ramblings indicate some possible lines of investigation of your
case.
Regards
Bill Bartlett
Birmingham Heartlands Hospital
-----Original Message-----
From: [log in to unmask]
[mailto:[log in to unmask]] On Behalf Of Dr
Sachidanandam Vivekanandan
Sent: 04 September 1998 15:12
To: [log in to unmask]
Cc: [log in to unmask]
Subject: Re: Isolated high urine dopamine
Could be uroblastoma?
Vivek
Chemistry
Guy's Hospital
On Fri, 4 Sep 1998 [log in to unmask] wrote:
>
>
>
> An unsolved case from the endocrinologists at our hospital: A middelaged
> female that for some years has suffered from attacks of flush and
anexiety,
> daily, in the morning. She has been treated for breast cancer a few years
> ago. Urine dopamine has repeatedly been around 50.000 nmol/day (HPLC, our
> reference < 2400 nmol/day), but occasionally normal, while urine
> epinephrine and norepinephrine has been normal. Plasma dopamine has been
> normal. Has anyone any suggestions?
>
> With kind regards
> Goran Brattsand, MD, Ph.D
> Clinical chemistry
> University hospial of northern Sweden, Umea, Sweden
> e-mail: [log in to unmask]
>
>
>
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