title: Levodopa treatment does not affect low-dose apomorphine test in patients with Parkinson's disease.
abstract: Challenge with low-dose apomorphine causes a significant rise in growth hormone (GH) in patients with Parkinson's disease (PD) compared to controls and patients with multiple system atrophy (MSA) who have not previously received dopaminergic treatment. To date, it has not been demonstrated whether an apomorphine-induced rise in GH can still be detected in PD patients who are currently treated with levodopa. We investigated whether an ongoing treatment with levodopa influences the GH response to subcutaneously applied low-dose apomorphine in PD patients. We studied 44 patients with idiopathic PD using the low-dose apomorphine test. Twenty-three patients were under treatment with levodopa and 21 patients were without any dopaminergic therapy. GH and cortisol levels were analyzed at time of injection and 45 minutes and 60 minutes after subcutaneous apomorphine injection. Forty-five minutes after apomorphine injection, there was no significant difference between the mean rise in plasma GH in untreated PD patients compared with levodopa-treated patients (P = 0.235). There was no increase of cortisol levels in each treatment group. Age, sex, duration, and severity of the disease did not show a covariate effect with GH levels. A small group of PD patients (n = 8) treated with dopamine agonists and a small group of patients with MSA (n = 5) as well as patients with vascular parkinsonism (n = 5) did not show any increase of GH. Our data suggest that the apomorphine-induced rise in GH does not depend on previous levodopa treatment in PD patients but, as expected, is blocked by dopamine agonists and is not present in patients with other than idiopathic parkinsonian syndrome. Thus, the low-dose apomorphine test may also be a useful biological marker in the early differential diagnosis of PD patients who have already received levodopa treatment.
authors.affiliation: Department of Clinical Neurophysiology, University of Göttingen, Germany. shappe@gwdg.de
authors.forename: Svenja
authors.initials: S
authors.lastname: Happe
authors.forename: Tobias
authors.initials: T
authors.lastname: Tings
authors.forename: Kathrin
authors.initials: K
authors.lastname: Helmschmied
authors.forename: Karin
authors.initials: K
authors.lastname: Neubert
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Wuttke
authors.forename: Walter
authors.initials: W
authors.lastname: Paulus
authors.forename: Claudia
authors.initials: C
authors.lastname: Trenkwalder
mesh_terms: D000328:Adult; D000368:Aged; D001058:Apomorphine / Q000008:administration & dosage; D004185:Disability Evaluation; D004298:Dopamine / Q000378:metabolism*; D018491:Dopamine Agonists / Q000008:administration & dosage / Q000627:therapeutic use*; D004334:Drug Administration Schedule; D005260:Female; D019382:Human Growth Hormone / Q000097:blood* / Q000187:drug effects; D006801:Humans; D006854:Hydrocortisone / Q000378:metabolism; D007279:Injections, Subcutaneous; D007980:Levodopa / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000188:drug therapy*; D012720:Severity of Illness Index
chemical_list: D018491:Dopamine Agonists; D019382:Human Growth Hormone; D007980:Levodopa; D001058:Apomorphine; D004298:Dopamine; D006854:Hydrocortisone