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Increased Growth Hormone Response to Apomorphine in Parkinson Disease Compared With Multiple System Atrophy
Elisabeth Friess, MD;
Tania Kuempfel, MD;
Juliane Winkelmann, MD;
Dagmar Schmid, MD;
Manfred Uhr, MD;
Rainer Rupprecht, MD;
Florian Holsboer, MD, PhD;
Claudia Trenkwalder, MD
Arch Neurol. 2001;58:241-246.
Background Parkinson disease (PD) is often difficult to distinguish from parkinsonian
syndromes of other causes in early stages of the disease. In search of a suitable
endocrinologic challenge test, we investigated dopaminergic sensitivity in
patients with de novo parkinsonian syndromes.
Objective We measured the growth hormone (GH) response to a subthreshold dose
of the dopamine 1–dopamine 2 receptor agonist apomorphine hydrochloride
to differentiate parkinsonian syndromes from PD.
Patients and Methods Seventeen patients with a clinical diagnosis of PD, 16 patients with
a clinical diagnosis of multiple system atrophy, and 11 healthy controls.
The GH response to a subthreshold dosage of apomorphine and to somatorelin
(GH-releasing factor) was tested in a randomized order; on the third day the
protocol was repeated with a clinically effective dose of apomorphine.
Results The GH response to the low dose of apomorphine was significantly increased
in patients with PD when compared with patients with multiple system atrophy
or the control subjects (multivariate analyses of covariance; univariate F
test, all P<.05). In contrast, there were no significant
group differences with use of the higher dose of apomorphine or in the somatorelin-induced
GH release.
Conclusions The GH response to a subthreshold dose of apomorphine appears to be
a useful tool to identify patients with PD vs multiple system atrophy. The
enhanced GH response to a subthreshold dopaminergic stimulus may reflect a
hypersensitivity of the extrastriatal dopamine receptors in PD.
From the Neurology Section, Max Planck Institute of Psychiatry, Munich,
Germany.
Corresponding author and reprints: Elisabeth Friess, MD, Max Planck
Institute of Psychiatry, Kraepelinstr 10, D-80804 Munich, Germany (e-mail: friess{at}mpipsykl.mpg.de).
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ABSTRACT
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