Therefore, the present study was carried out with the aim of determining the proportion of individuals with low serum IGF-1 levels and/or failing to respond to the combined GH-releasing hormone (GHRH) plus arginine test in a cohort of FM subjects with severe obesity.
All subjects underwent a standard GHRH plus arginine test, which was performed within one week from the diagnosis of FM.
Considering all patients, the rate of failure in GH response to the combined GHRH plus arginine test was 12.5% (2 out of 16 patients, PT#13 and PT#14, both belonging to the subgroup with low IGF-1 SDS values) (Figure 2).
Therefore, using the GHRH plus arginine test might have overestimated GH response in any patient, given the potential hypothalamic effects of arginine on the "dysregulated" GH/IGF-1 axis present in FM.
In conclusion, the present study shows that a not negligible subpopulation (25%) of patients with both FM and severe obesity has low IGF-1 SDS values, 12.5% failing also to normally respond to the GHRH plus arginine test. This seems to be a consequence of the obese rather than fibromyalgic condition, a conclusion that should be cautiously considered because of the small number of patients recruited.
Caption: Figure 1: Serum concentrations of GH in FM obese patients (all data and subjects with normal or low IGF-1 SDS values), who underwent the combined GHRH plus arginine test. Data are expressed as mean [+ or -] SD.
Twelve male domestic shorthair cats were tested using an intravenous arginine test
(IVAST), a meal response test (MRT) and an IV glucose response test (IVGTT).