M L Hartman’s research while affiliated with United States Naval Research Laboratory and other places

Context In clinical practice, the safety profile of GH replacement therapy for GH-deficient adults compared with no replacement therapy is unknown. Objective The objective of this study was to compare adverse events (AEs) in GH-deficient adults who were GH-treated with those in GH-deficient adults who did not receive GH replacement. Design and Setting This was a prospective observational study in the setting of US clinical practices. Patients and Outcome Measures AEs were compared between GH-treated (n = 1988) and untreated (n = 442) GH-deficient adults after adjusting for baseline group differences and controlling the false discovery rate. The standardized mortality ratio was calculated using US mortality rates. Results After a mean follow-up of 2.3 years, there was no significant difference in rates of death, cancer, intracranial tumor growth or recurrence, diabetes, or cardiovascular events in GH-treated compared with untreated patients. The standardized mortality ratio was not increased in either group. Unexpected AEs (GH-treated vs untreated, P ≤ .05) included insomnia (6.4% vs 2.7%), dyspnea (4.2% vs 2.0%), anxiety (3.4% vs 0.9%), sleep apnea (3.3% vs 0.9%), and decreased libido (2.1% vs 0.2%). Some of these AEs were related to baseline risk factors (including obesity and cardiopulmonary disease), higher GH dose, or concomitant GH side effects. Conclusions In GH-deficient adults, there was no evidence for a GH treatment effect on death, cancer, intracranial tumor recurrence, diabetes, or cardiovascular events, although the follow-up period was of insufficient duration to be conclusive for these long-term events. The identification of unexpected GH-related AEs reinforces the fact that patient selection and GH dose titration are important to ensure safety of adult GH replacement.

The effects of GH replacement on glucose metabolism in GH-deficient (GHD) adults in clinical practice are not well defined. Therefore, we assessed GH treatment effects on fasting plasma glucose (FPG) and haemoglobin A1c (A1c) concentrations in GHD adults in a clinical setting. Post-hoc analysis of the observational Hypopituitary Control and Complications Study conducted at 157 US centres (1997-2002). GH-deficient adults who were GH-naïve at study entry and had at least two FPG measurements. Effect of GH treatment on the frequency and time course of abnormal FPG (> or =5.6 mmol/l) development, FPG normalization, progression of increased FPG and abnormal follow-up A1c (>6%) values in GHD patients treated with GH (n = 403) or untreated (n = 169) at their physician's discretion. In subjects without pre-existing diabetes mellitus, development of an abnormal FPG tended to occur in a greater percentage of GH-treated than untreated subjects (35.3% versus 24.5, P = 0.06). Additionally, GH treatment was associated with a mild, transient increase in FPG and shorter time to development of an abnormal FPG in these subjects (P < 0.01). Most ( approximately 80%) abnormal FPG values were below 7 mmol/l and normalized in 69% of GH-treated subjects without diabetes. Treatment with GH had no effect on the rate of FPG normalization, progression of increased FPG or abnormal follow-up A1c values. Initiation of GH replacement in GHD adults was associated with a mild increase in FPG that often normalized spontaneously. Nevertheless, clinicians should monitor FPG in patients receiving GH treatment.

GH therapy in adult patients with GH deficiency (GHD) was approved over 10 yr ago, and the indication has subsequently gained broad acceptance. The HypoCCS surveillance database is a suitable means to examine the evolution of diagnostic patterns since 1996. Baseline demographics, reported cause of GHD, and diagnostic tests were available from 5893 GH-treated patients. Trends for change over time in diagnosis, GH stimulation test data, and IGF-I measurements were analyzed at 2-yr intervals by linear regression models, with entry year as the predictive variable. Over the decade, there was a decrease in patients enrolled with diagnoses of pituitary adenoma (50.2 to 38.6%; P < 0.001), craniopharyngioma (13.3 to 8.4%; P = 0.005) and pituitary hemorrhage (5.8 to 2.8%; P = 0.001); increases in idiopathic GHD (13.9 to 19.3%; P < 0.001), less common diagnoses (7.4 to 15.8%; P < 0.001), and undefined/unknown diagnoses (1.3 to 8.6%; P < 0.001) were observed. Use of arginine, clonidine, and L-dopa tests declined, whereas use of the GHRH-arginine test increased. Median values for peak GH from all tests except GHRH-arginine and for IGF-I SD scores increased significantly (P < 0.001). Over the decade (1996--2005), idiopathic GHD was reported for 16.7% of patients, and more than half of these had adult onset GHD. In the idiopathic adult onset group, 40.2% had isolated GHD; 18.3 and 4.4% had a stimulation test GH peak of at least 3.0 and 5.0 microg/liter, respectively. Significant shifts in diagnostic patterns have occurred since approval of the adult GHD indication, with a trend to less severe forms of GHD.

Several studies have demonstrated an improvement in aerobic exercise capacity with 6 months of GH replacement in adults with GH deficiency (GHD). The objective of the study was to determine whether improvements in aerobic exercise capacity with GH treatment in adults with GHD are related to changes in physical activity or affected by the GH dosing regimen. This was a randomized, two-arm, parallel, open-label study. The study was conducted at five academic medical centers with exercise physiology laboratories. Study subjects were adults (n = 29) with GHD due to hypothalamic-pituitary disease. The intervention was GH replacement therapy, administered either as a fixed body weight-based dosing regimen as an individualized dose titration regimen for 32 wk. Maximal oxygen consumption (VO2 max) and oxygen consumption (VO2) at the lactate threshold, ventilatory threshold using a cycle ergometry protocol, and weekly energy expenditure (physical activity questionnaire), assessed at baseline and end point, were measured. In the group as a whole, VO2 max increased significantly (by 9%) from baseline (19.1+/- 0.89 ml/kg.min) to end point (21.6 +/- 1.23 ml/kg.min, P = 0.010). Compared with baseline, VO2 max also changed significantly within the individualized dose titration regimen group (+2.5 +/- 0.98 ml/kg.min, P =0.034) but not within the fixed body weight-based dosing regimen group (+1.2 +/- 0.78 ml/kg.min, P = 0.15), although these changes from baseline were not significantly different between the two groups. VO2 at lactate threshold, VO2 at ventilatory threshold, and weekly energy expenditure also did not change. GH replacement therapy in GH-deficient adults improved VO2 max similarly with both dosing regimens, without any influence of physical activity. There was no effect on submaximal exercise performance.

To determine if replacement of GH improves BMD in adult-onset GHD, we administered GH in physiologic amounts to men and women with GHD. GH replacement significantly increased spine BMD in the men by 3.8%. Growth hormone (GH) deficiency (GHD) acquired in adulthood results in diminished BMD; the evidence that replacement of GH improves BMD is not conclusive. We therefore performed a randomized, placebo-controlled trial to determine whether GH replacement would increase lumbar spine BMD in a combined group of men and women with adult-onset GHD. We randomized 67 men and women to receive GH (n=33) or placebo (n=34) for 2 yr. The GH dose was initially 2 microg/kg body weight/d, increased gradually to a maximum of 12 microg/kg/d and adjusted to maintain a normal IGF-I concentration for age and sex. BMD was assessed before treatment and at 6, 12, 18, and 24 mo of treatment. Fifty-four subjects completed the protocol. BMD of the lumbar spine in the entire group increased by 2.9 +/- 3.9% above baseline in the GH-treated subjects, which was significantly (p=0.037) greater than the 1.4 +/- 4.5% increase in the placebo-treated subjects. In a secondary analysis, spine BMD in GH-treated men increased 3.8 +/- 4.3% above baseline, which was significantly (p=0.001) greater than that in placebo-treated men (0.4 +/- 4.7%), but the change in GH-treated women was not significantly different from that in placebo-treated women. Treatment with GH did not increase total hip BMD more than placebo treatment after 2 yr. We conclude that GH replacement in men who have adult-onset GHD improves their spine BMD, but we cannot draw any conclusions about the effect of GH replacement on spine BMD in women with adult-onset GHD.

To determine whether an individualized dose titration regimen (ID) for adult GH replacement therapy would have similar efficacy and better tolerability than a fixed body weight-based dosing regimen (FD), 387 adults with GH deficiency were randomized to FD (n = 200) or ID (n = 187) for 32 wk. In FD, subjects received sequentially 4, 8, and 12 microg/kg.d GH. ID was started at 0.2 mg/d and increased by 0.2-mg/d increments, based on clinical and serum IGF-I responses, to a maximum of 0.8 mg/d. Increases (mean +/- sd) in serum IGF-I were similar in both groups (FD, 110.2 +/- 87.8 vs. ID, 99.6 +/- 77.7 microg/liter, P = 0.20) despite higher final GH doses in FD (0.70 +/- 0.32 vs. 0.54 +/- 0.22 mg/d, P < 0.001). Favorable changes in several efficacy measures were observed with no significant differences between the FD and ID groups: lean body mass increased; health-related quality of life improved; and abdominal fat mass, hip circumference, sum of skinfolds, and total and low-density lipoprotein cholesterol decreased. The decrease in fat mass was greater with FD than ID for men (-2.7 +/- 2.7 kg vs. -1.8 +/- 2.5 kg, P = 0.04) but not for women (-2.1 +/- 2.4 vs. -2.0 +/- 3.8 kg). The change in waist circumference was greater with FD than ID for women but not for men. There was a significant reduction of systolic blood pressure in ID but not in FD. The adverse event profile was similar between FD and ID except that ID had a lower occurrence of peripheral edema (9.1% vs. 16.5%, P = 0.03) and rash (1.1% vs. 5.5%, P = 0.02) than FD. In summary, the use of ID resulted in improved tolerability and similar efficacy compared with FD. We conclude that GH replacement therapy should be initiated at a low dose and titrated to a dose producing maximal benefits without adverse side effects and an IGF-I level within the age- and sex-adjusted normal range.

To develop reference ranges for the Questions on Life Satisfaction Hypopituitarism Module (QLS-H), a new quality of life questionnaire for patients with hypopituitarism, data from 8177 adults were collected in France, Germany, Italy, The Netherlands, Spain, the United Kingdom, and the United States QLS-H scores declined with age, were lower in females than males, and differed significantly among countries. From these reference ranges we derived equations for z-scores, which adjust for age, gender, and country. QLS-H results from 957 adults with GH deficiency (GHD) participating in clinical trials were analyzed. At baseline, QLS-H scores were lower in females and differed significantly among countries. QLS-H scores significantly increased after GH treatment (6-8 months), but differences by country persisted. Calculating z-scores for patients eliminated all gender and most country differences. Pooled z-scores (mean +/- SD) from all patients increased from -0.99 +/- 1.39 at baseline to -0.14 +/- 1.30 after GH treatment. Quality of life assessment in adults with GHD requires the use of z-scores to correct for age, gender, and country differences. This approach allows pooling of data from different cohorts and comparison with general populations. QLS-H scores in adults with GHD were significantly decreased at baseline and were almost normalized after 6-8 months of GH therapy.

We examined the relationship between abdominal visceral fat (AVF) and plasma concentrations of lipids and lipoproteins in 19 females (F) (not on estrogen) and 31 males (M) over the age of 60 (age = 66.8 years). In addition, the effects of growth hormone (GH) release, fitness (Vo(2) peak), insulin, and glucose concentrations (both fasting and in response to an oral glucose tolerance test) on lipids were examined. Subjects were categorized by low (L) and high (H) AVF (L < 130 cm(2), H > 130 cm(2)), fat mass (FM) (above or below median value), and AVF corrected for fat mass. Factorial analysis of variance (ANOVA) showed that when subjects were divided by AVF and FM, similar results were observed with H > L (P <.05) for very-low-density lipoprotein- cholesterol (VLDL-C), triglycerides (TG), VLDL-TG, apolipoprotein (apo)- B, apo-B VLDL, cholesterol (Chol)/high-density lipoprotein (HDL), LDL/HDL, apoB/A1 and L > H for HDL, HDL(2), HDL(3), apo A1, and LDL/apo- B LDL. Gender differences were also observed with F > M for Chol, LDL, HDL, and HDL(2). When AVF was corrected for FM, these gender differences were still present. After correcting for FM, differences remained between H and L AVF groups for VLDL, TG, VLDL-TG, apo-B, apo-B LDL, apo-B VLDL, apoB/A1 (P <.05). Twenty-four hour integrated GH concentration (IGHC) was inversely related to VLDL, TG, VLDL TG, LDL

Arginine stimulates growth hormone (GH) secretion, possibly by inhibiting hypothalamic somatostatin (SS) release. Insulin-like growth factor I (IGF-I) inhibits GH secretion via effects at the pituitary and/or hypothalamus. We hypothesized that if the dominant action of IGF-I is to suppress GH release at the level of the pituitary, then the arginine-induced net increase in GH concentration would be unaffected by an IGF-I infusion. Eight healthy young adults (3 women, 5 men) were studied on day 2 of a 47-h fast for 12 h (35th-47th h) on four occasions. Saline (Sal) or 10 microg. kg(-1). h(-1) recombinant human IGF-I was infused intravenously for 5 h from 37 to 42 h of the 47-h fast. Arginine (Arg) (30 g iv) or Sal was infused over 30 min during the IGF-I or Sal infusion from 40 to 40.5 h of the fast. Subjects received the following combinations of treatments in random order: 1) Sal + Sal; 2) Sal + Arg; 3) IGF-I + Sal; 4) IGF-I + Arg. Peak GH concentration on the IGF-I + Arg day was ~45% of that on the Sal + Arg day. The effect of arginine on net GH release was calculated as [(Sal + Arg) - (Sal + Sal)] - [(IGF-I + Arg) - (IGF-I + Sal)]. There was no significant effect of IGF-I on net arginine-induced GH release over control conditions. These findings suggest that the negative feedback effect of IGF-I on GH secretion is primarily mediated at the pituitary level and/or at the hypothalamus through a mechanism different from the stimulatory effect of arginine.

Cortisol and growth hormone (GH) are released in response to a variety of pharmacologic and physiologic stimuli. Secretion of cortisol and GH are influenced by age, gender, time of day, nutrition, sleep, body composition, and fitness level. Exercise is one of the most potent stimulators for release of these hormones. A single session of exercise of sufficient intensity will result in dramatic increases in cortisol and GH concentrations in most individuals and may take a few hours to recover back to baseline levels. Cortisol and GH are necessary for optimal exercise performance, which is most evident in chronic cortisol and GH deficiency. In deficient individuals, replacement therapy with cortisol or GH restores normal exercise performance. Exercise training can substantially alter the degree of perturbation of the hypothalamic-pituitary axis. The cortisol response pattern to exercise has been considered to be predictive of an individual's adaptation to other forms of stress. This review discusses the cortisol and GH responses to exercise, the factors affecting these responses, the mechanisms of hormone release, and the clinical implications of these physiological observations.