[Changes in growth hormone/insulin-like growth factor-1 axis in patients with normal pituitary function and...

Previous studies showed increased growth hormone (GH) plasma levels in patients with severe heart failure. It has been hypothesized that the activation of adenohypophysis determines the enhanced release of GH. The present study was designed to verify whether impaired hepatic function, due to biventricular cardiac failure and hepatic stasis, by reducing synthesis and release of insulin-like growth factor-1 (IGF-1), may affect the negative feedback mechanism of the IGF-1 on GH secretion. We studied 20 normotensive, non diabetic patients without primitive liver disease; 10 patients in NYHA functional class IV with clinical signs of biventricular cardiac impairment and hepatic stasis (Group A); 10 patients in NYHA functional class III with prevalent left ventricular dysfunction (Group B). Blood samples for radioimmunologic determination of GH, IGF-1, atrial natriuretic factor (ANF), proteins, albumin plasma levels and transaminase plasma levels measurements, were collected 24 hours before hemodynamic study. Group A patients had clinical and hemodynamic signs of hepatic stasis with impaired liver function (SGOT 68 +/- 5.5 U/l; SGPT 89 +/- 4.3 U/1; proteins 4.56 +/- 0.4 g/dl with albumin/globulin ratio < 1; albumin plasma levels 2.8 +/- 0.7 g/dl). The parameters were normal in Group B (SGOT 16 +/- 3.7 U/l;SGPT 13 +/- 1.9 U/l; proteins 7.5 +/- 0.7 g/dl with albumin/globulin ratio > or = 1.5;albumin plasma levels 4.2 +/- 1.2 g/dl). ANF values, over normal range in both groups, were significantly higher in Group A (157.9 +/- 43.9 vs 65.6 +/- 14.6 fmol/ml.p < 0.0001). In Group A GH values were increased (4.9 +/- 4.5 vs 0.12 +/- 0.04 ng/ml); on the contrary IGF-1 values were lower (187.9 +/- 98.2 vs 260.4 +/- 141.4 ng/ml, p < 0.01). The comparison between IGF-1 and albumin plasma levels showed a high correlation either in Group A (r = 0.88, p < 0.001;) or in Group B (r = 0.81, p < 0.001). Our findings allow to hypothesize that the reduced hepatic synthesis and release of IGF-1 may be responsible for the lack of trophic action of GH on cardiac myocytes in patients with biventricular heart failure and hepatic stasis.