Objective: To analyze the sensitivity and specificity of the clonidine growth hormone (CGH) to distinguish probable multiple system atrophy (MSA) from pure autonomic failure (PAF), Parkinson disease (PD), and progressive supranuclear palsy (PSP).

Background: There is a shortage of effective non-invasive biomarkers to distinguish among various subtypes of parkinsonism

Method: We retrospectively evaluated 12 Autopsy confirmed MSA, 13 PSP, 36 PAF, and 25 PD patients who underwent the clonidine growth hormone stimulation in our unit. PD was clinically diagnosed as per UK Brain Bank criteria except four who had postmortem diagnosis. PSP was diagnosed clinically except for four patients who had postmortem diagnosis. PAF was diagnosed clinically as per American Academy of Neurology consensus criteria. Serum growth hormone (GH) was measured before the intravenous clonidine stimulation and after 15, 30, 45, and 60 minutes of the stimulation. Measurement of GH was performed by radioimmunoassay kit.

Results: GH level at any time point after the clonidine stimulation was significantly lower (p<0.05) in MSA compared to PD, PAF, normal population, and PSP. (Figure 1 & 2 ) The rise of the GH level showed good sensitivity and specificity in differentiating MSA from other parkinsonian syndromes (MSA vs PSP; sensitivity-92.3% and specificity-50%, MSA vs PD; sensitivity- 92% and specificity-50%, MSA vs PAF; sensitivity -60% and specificity-83.3%).

Conclusion: This is the first ever CGH study to include definite MSA patients. MSA uniformly showed a suboptimal response after clonidine infusion. The CGH test can be considered as a potential biomarker for the diagnosis of MSA in the future.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/the-study-of-clonidine-growth-hormone-study-amongst-definite-msa-pd-psp-and-paf-patients-to-assess-its-feasibility-as-a-future-non-invasive-biomarker/