Patients
We enrolled 16 acromegalic patients (8 men and 8 women), who developed GHD after combined pituitary surgery and radiotherapy in the study. Inclusion criteria were previous treatment for acromegaly by surgery and/or radiotherapy and an insufficient GH increase to insulin-induced hypoglycemia (short-acting insulin 0.05–0.1 U/kg body weight, blood samples drawn at 0, 20, 30, 45, 60 and 90 min; nadir glucose levels below 2.2 mmol/l) [9]. The increase in GH concentrations was considered insufficient, when the peak GH response was below 3 μg/l [10].
Fifteen patients had been treated with primary surgery and secondary conventional radiotherapy mean interval after radiotherapy 18 years (range 4–29 years). The other patient was diagnosed with pituitary apoplexy of a GH producing adenoma. Because GH concentrations remained elevated, he underwent surgery and subsequently developed complete anterior pituitary failure. Clinical details were published previously [11].
Additional hormone replacement therapy was kept stable for at least 3 months prior to study inclusion, and was only adjusted thereafter when necessary. The purpose, nature, and possible risks of the study were explained to all subjects and written informed consent was obtained. The study protocol was approved by the ethics committee of the Leiden University Medical Center.
Study design
Study parameters were assessed both at baseline and after 1 year of rhGH replacement. The following variables were measured: fasting concentrations of lipoproteins, glucose, and IGF-I, body composition, bone turnover markers and bone mass, echocardiography, and Quality of Life parameters.
Growth hormone vials of 1 ml were manufactured and provided by Novo Nordisk Pharma, Denmark. Growth hormone replacement dose was started at 0.2 mg/day and, subsequently, titrated in the first 12 weeks of the study to obtain an IGF-I concentration within the age- and gender-adjusted reference range, according to Growth Hormone Research Society guidelines [10].
The mean age of the patients was 56 years (range 34–75 years). The interval between radiotherapy and the start of the study was 18 years (range 4–29 years). TSH deficiency was present in five patients, ACTH deficiency in nine patients, and LH-FSH deficiency in eight patients (see Table 1).
Table 1 Clinical characteristics of the 16 patients with growth hormone deficiency after acromegaly
Body composition
Body weight and height, waist circumference, hip circumference, systolic and diastolic blood pressure (SBP and DBP, respectively) were measured. Waist-hip (WH) ratio was calculated. Body weight was measured to the nearest 0.1 kg, and body height was measured barefoot to the nearest 0.001 m. Lean body mass and fat mass were measured with DXA (Hologic 4500; Hologic Inc., Waltham, MA, USA).
Markers for bone turnover and bone mass
The following serum markers of bone turnover were measured: N-terminal propeptides of type I collagen (PINP), as a marker for bone synthesis, and β-crosslaps as a marker for bone resorption. Bone mineral density (BMD) was measured by DXA (Hologic 4500; Hologic Inc., Waltham, MA, USA). Sites measured were the lumbar spine (L1-L4) and the femoral neck (left and right). Mean BMD of the left and right femoral neck was calculated. Mean T and Z scores were calculated for total left and right hip using the NHANES reference values. The CV of BMD measurements was 1% and the machine was cross-calibrated at regular interval.
Echocardiography
Echocardiography was performed while the patients were in the left lateral decubitus position using a commercially available system (Vingmed Vivid-7, General Electric-Vingmed, Milwaukee, WI, USA). Standard parasternal (long- and short-axis) and apical views (2-, and 4-, and long-axis) were obtained. M-mode images were obtained from the parasternal long-axis views for quantitative assessment of LV dimensions (inter-ventricular septum thickness (IVST), posterior wall thickness (PWT), LV end-diastolic diameter (LVEDD), LV end-systolic diameter (LVESD), fractional shortening (FS) and LV ejection fraction (LVEF)) [12].
The following parameters of diastolic function were obtained: diastolic transmitral peak velocities (E and A wave) and the E/A ratio. Quantitative diastolic data were derived from tissue Doppler imaging (TDI). For TDI analysis, the digital cine loops were analyzed using commercial software (Echopac 6.1; General Electric-Vingmed). The sample volume (4 mm2) was placed in the LV basal portion of the septum (using the 4-chamber views). The following parameters (mean values calculated from three consecutive heartbeats) were derived: early diastolic velocity (E′), late diastolic velocity (A′) and the E′/A′ ratio. The severity of valvular regurgitation was assessed by two independent expert readers blinded to the clinical data on a qualitative scale of trace, mild, moderate, or severe, using previously described methods [13, 14]. Left ventricular mass (LVM) was calculated by the cube formula, and using the correction formula proposed by Devereux et al. [15]: 0.8 × {1.04 [(LVEDD + PWT + IVST)3 − LVEDD3]} + 0.6. The data were assessed by two independent observers, blinded for the clinical data of the patients.
Quality of life
Quality of life was assessed using four different validated health-related quality of life questionnaires
Hospital anxiety and depression scale (HADS): The HADS consists of 14 items pertaining to anxiety and depression. Each item is measured on a 4-point scale. Scores for the anxiety and depression subscale range from 0 to 21 and for the total score from 0 to 42. A high score points to more severe anxiety and depression [16].
Multidimensional fatigue index (MFI-20): The MFI-20 contains 20 statements to assess fatigue [17]. Five different dimensions of fatigue (four items each) are calculated from these statements; (1) general fatigue; (2) physical fatigue; (3) reduced activity; (4) reduced motivation and (5) mental fatigue. Every statement is measured on a 5-point scale; scores vary from 0 to 20. Higher scores indicate higher experienced fatigue.
Nottingham health profile (NHP): The NHP is frequently used in patients with pituitary disease to assess general well-being and QoL. The survey consists of 38 yes/no questions, which are subdivided in 6 scales assessing impairments, i.e. pain (8 items), energy level (3 items), sleep (5 items), emotional reactions (9 items), social isolation (5 items) and disability/functioning, i.e. physical mobility (8 items) [18, 19]. Subscale scores are calculated as a weighted mean of the associated items and are expressed as a value between 0 and 100. The total score is the mean of the six subscales.
Quality of life-assessment of growth hormone deficiency in adults (QoL-AGDHA): This disease specific quality of life questionnaire has been developed specifically for the detection of deficits in needs achievements in areas which have shown to be commonly affected in adults with GHD [20]. The questionnaire comprises 25 items, which are summed to form a total score. Higher numerical scores (to a maximum of 25) denote poorer quality of life.
Assays and dynamic tests
Growth hormone reserve was evaluated by the insulin tolerance test in fasting conditions (short-acting insulin 0.05–0.1 U/kg body weight, blood samples drawn at 0, 20, 30, 45, 60 and 90 min; the nadir glucose concentration should drop below 2.2 mmol/l) [9]. The increase in GH concentration was considered insufficient, when the peak GH concentration was below 3 μg/l [10].
Serum IGF-I concentration was measured with the Immulite 2500 system (Diagnostic Products Corporation, Los Angeles, USA). The intra-assay variation was 5.0 and 7.5% at mean serum levels of 8 and 75 nmol/l, respectively. IGF-I levels are expressed as standard deviation-scores (SDS), using lambda-mu-sigma (LMS) smoothed reference curves based on measurements in 906 healthy individuals [21, 22].
IGFBP-3 was measured using an immunometric technique on an IMMULITE Analyzer (Diagnostic Products Corporation, Los Angeles, USA). The lower limit of detection was 0.02 mg/l and inter-assay variation was 4.4 and 4.8% at 0.91 and 8.83 mg/l. A Hitachi P800 auto analyzer (Roche, Mannheim, Germany) was used to quantify serum concentrations of glucose, total cholesterol and TG. HDL was measured with a homogenous enzymatic assay (Hitachi 911, Roche, Mannheim, Germany). LDL cholesterol concentrations (LDL) were calculated using the Friedewald formula. C-crosslinking terminal telopeptide of type I collagen (β-crosslaps) and procollagen type I aminoterminal propeptide (PINP) by chemoluminescence immunoassay with the Modular Analytics E-170 system (Roche Diagnostics, Almere, The Netherlands).
Statistics
Statistical analysis was performed using SPSS for Windows, version 14.0 (SPSS Inc. Chicago, Illinois, USA). Results are scored as the mean ± standard deviation (SD), unless specified otherwise. The data were analyzed with the paired samples Student’s t-test. Statistical significance was set at P < 0.05.