Growth hormone and ghrelin secretion are associated with clinical severity in Huntington's disease

Huntington's disease (HD) is a fatal hereditary neurodegenerative disorder caused by an increased CAG repeat size in the huntingtin gene. Apart from neurological impairment, the disease is also accompanied by progressive weight loss, abnormalities in glucose homeostasis and a higher prevalence of diabetes mellitus, which may partly be caused by disturbed growth hormone (GH) and ghrelin secretion. Therefore, we aimed to perform a detailed analysis of GH and ghrelin secretion in HD patients in relation to clinical signs and symptoms.

In nine early-stage, medication-free HD patients and nine age-, gender- and body mass index-matched controls, we measured serum GH levels every 10 min for 24 h and assessed ghrelin response to food intake. Multi-parameter auto-deconvolution and approximate entropy analysis were applied to quantify basal, pulsatile, and total GH secretion rates as well as the regularity of GH secretion.

We found no significant differences in GH and ghrelin secretion characteristics between HD patients and controls (total GH secretion: 137 +/- 36 vs. 181 +/- 43 mU/l/24 h, respectively; P = 0.439). However, in HD patients, both GH secretion and its irregularity as well as the degree of postprandial ghrelin suppression significantly increased with worsening motor and functional impairment (all P < 0.05). Moreover, postprandial ghrelin suppression also increased with decreasing body weight and higher CAG repeat number (both P < 0.05).

These findings suggest changes in the regulation of GH and ghrelin secretion dynamics in early stage HD patients that could become more prominent in the later stages of the disease.