Growth Hormone deficiency is believed to play a role in the pathogenesis of ALS [1-3]. Whilst GH/IGF-1 directed therapies have been trialed for the treatment of ALS, the outcomes are far from promising [4-6]. To better understand how, or if altered GH secretion plays a pathogenic role in ALS, we assessed the endogenous profile of GH secretion in wild-type and hSOD1G93A mice at different stages of disease progression. Male wild-type and hSOD1G93A transgenic mice were assessed at the pre-symptomatic (30-36 days), onset (63-75 days) and end-stage of disease (150-175 days). Blood samples (2 or 4μl) were collected over a 6hr period at 10min intervals starting at 0700hrs and assessed for GH [7]. We quantified pathological hallmarks of disease by determining motor neuron number and neuromuscular innervation. We demonstrate that hSOD1G93A mice have a dynamic GH secretion profile throughout disease progression; GH secretion is normal during the pre-symptomatic stage of disease, GH hypersecretion occurs at the onset of disease symptoms, and GH deficiency manifests at the later stage of disease. Correlation analysis of GH secretion with motor neuron number and neuromuscular innervation indicate that GH hypersecretion is positively correlated with a higher percentage of neuromuscular innervation, but not with motor neuron number. Interestingly, GH hypersecretion occurred in parallel with an increase in the expression of muscle IGF-1. Given that the first measurable differences in GH/IGF-1 are observed in hSOD1G93A mice at an age that corresponds to the onset of disease symptoms, our results suggest that altered GH/IGF-1 secretion in ALS occurs as a consequence of the disease process. Moreover, our correlation data implies that GH does not have a direct neuroprotective role in ALS. Rather, GH appears to have an indirect effect by driving an increase in the local expression of muscle IGF-1. This endogenous endocrine response may serve to promote muscle repair due to the onset of muscle pathology in ALS.