Changes Of Serum Levels Of Growth Hormone And Insulin-like Growth Factor-I In Patients With Dilated Cardiomyopathy

Objective: To investigate the changes of serum levels of growth hormone(GH) and insulin-like growth factar-I (IGF-I) and patients with dilated cardiomyopathy(DCM) and its significance.Methods: Serum levels of GH and IGF-I were measured with radioimmunoassay in 33 patients with DCM and 24 healthy control subjects at 8Am, 4Pm, 12Pm within 24 hours. Left ventricular ejection fraction (LVEF) was obtained by echocardiography.Results: (1)Changes of serum GH and IGF-I levels: In patients with DCM, either men or women, serum levels of GH and IGF-I at three time spots as well as mean GH and IGF-I were lower than those in healthy control subjects, but no significant difference was observed; in the changes of rhythm of day and night, serum GH levels in the patients with DCM and healthy control subjects at 12Pm were significantly higher than those at 8Am(P<0.05), and serum levels of IGF-I at 12Pm were lower than those of IGF-I at 8Am and 4Pm. (2) Relationship between LVEF and serum levels of GH or IGF-I: Between serum levels of GH at three time spots and mean GH and LVEF value in patients with DCM, positive significant correlation were found (r=0.527, P=0.002 at 8Am; r=0.548, P=0.001 at 4Pm; r=0.410, P=0.047 at 12Pm; r=0.515, P=0.002 for mean GH; respectively). The patients with DCM were divided into two subgroups according to LVEF. In the patients with LVEF≤0.20, serum GH levels at three time spots and mean GH were significantly reduced compared to the subgroup of patients with DCM and LVEF>0.20 and to healthy control subjects, and serum levels of IGF-I at three time spots and mean IGF-I were also significantly reduced in comparison with healthy control subjects. (3)Relationship between cardiac function and serum levels of GH and IGF-I: The decrease of serum levels of mean GH and IGF-I in patients with DCM closely correlated with the severity of symptoms of congestive heart failure (CHF). Serum levels of mean GH and IGF-I in patients with DCM in New York Heart Association (NYHA) classⅣ were significantly reduced compared to healthy control subjects (1.24±0.6 vs. 2.33±0.77ng/ml, P=0.032; 163.16±0.75 vs. 267.96±60.11ng/ml, P=0.018, respectively), but no significant differences were observed among classes. (4)Relationship between serum GH levels and serum IGF-I levels: Either DCM group or healthy control subjects, no significant correlation was found between serum GH levels and serum IGF-I levels at three time spots or between mean GH and mean IGF-I level. Conclusion: The present study shows that the serum levels of GH and IGF-I are decreased in patients with DCM in comparison with those in healthy control subjects, especially in the patients with LVEF≤0.20. Serum levels of GH were positive significant correlation with LVEF in patients with DCM. The result suggest that serum levels of GH and IGF-I may serve as a sensitive target in reflecting the severity of CHF. In patients with DCM, supplement of appropriate GH may have a role in improving of cardiac function.