Endocrine Abstracts

Objective: Hypopituitary patients receiving convensional hormone substitution, but without growth hormone (GH) replacement, have an increased mortality from cardiovascular disease. The aim of the present study was to assess the heart rate variability(HRV) in hypopituitary patients with severe GH deficiency.

Material and method: Thirty-five patients (20 women, 15 men, aged 23-75 years) with severe GH deficiency, all of 35 patients with low insulin-like growth factor-1 (IGF1) levels, and 18 sex- age-matched healthy controls. The causes of hypopituitarism were as follows: 17 patients had operated pituitary adenoma, 14 had empty sellae, three had Sheehan syndrome, one patient had prolactinoma. Twenty-four-hour ECG monitoring was performed to detect HRV parameters. HF was accepted as a marker of parasympathetic activity and LF as sympathetic activity. As an indicator of sympatho-vagal equilibirium LF/RF ratio was measured. The decrease in SDNN has been used as decreased in vagal activity and increased sympathetic activity in sinus node.

Results: Patients with GH deficiency had lower values of SDNN, RMSSD, PNN50, LF, HF compared to controls but these were not statistically significant. HF/RF ratio was minimally higher in patients than in controls. The average heart rate and maximal heart rate values were lower significantly compared to controls (respectively 75.11±8.9 vs 80.6±7.49, P=0.03, and 133.20±15.77 vs 149.22±18.55, P=0.002). There was no difference in minimum heart rate values between patients and controls.

Conclusion: Hypopituitary GH deficient patients have increased mortality due to cardiovascular disease. However their autonomic functions don’t appear to contribute this mortality rate.