Influence of substrate background on peripheral tissue responses to growth hormone

Nutritional, respiratory, and psychological effects of recombinant human growth hormone in patients undergoing abdominal aortic aneurysm repair

BACKGROUND

Recombinant human growth hormone (rhGH) has been shown to have powerful anabolic effects and to reduce or even prevent nitrogen catabolism in stressed patients. The effects of rhGH on functional parameters are less clearly defined. The aim of this study was to assess the effects of perioperative rhGH on nutritional markers, skeletal muscle function, and psychological well-being in patients undergoing infrarenal, abdominal aortic aneurysm repair.

METHODS

Thirty-three patients undergoing elective infrarenal abdominal aortic aneurysm repair were randomized to one of three groups: (1) control (n = 12): placebo for 6 days before and after surgery; (2) preop + postop (n = 10): rhGH (Genotropin; Pharmacia Ltd, Uppsala, Sweden) 0.3 IU/kg/d for 6 days before and after surgery; and (3) postop (n = 11): placebo for 6 days before and rhGH 0.3 IU/kg/d for 6 days after surgery. Patients were assessed on days -7 and -1 before surgery and days 7, 14, and 60 after surgery.

RESULTS

Administration of rhGH resulted in increased insulin-like growth factor 1 levels, the increase being significantly more marked in the group given rhGH preoperatively. Preoperative and postoperative rhGH reduced the postoperative decrease in both serum transferrin and grip strength at day 7 by 30% and 70%, respectively. Postoperative respiratory function and arterial oxygenation also were improved, with significant differences in arterial oxygenation between rhGH-treated and untreated groups. No difference in mood was seen between groups after surgery, nor was there any difference between subjective assessment of fatigue scores between groups.

CONCLUSIONS

This pilot study indicates that rhGH administered preoperatively has beneficial effects on skeletal muscle and respiratory function and may be more useful than postoperative rhGH administration alone.

Anabolic effects of growth hormone treatment in young children with cystic fibrosis

BACKGROUND

Malnutrition is commonly found in children with Cystic Fibrosis (CF) and is characterized by poor weight gain and linear growth. Almost one-third of children with CF are below 5th percentile for weight and height. Intensive nutritional supplementation may not result in sustained improvement in weight gain and linear growth.

OBJECTIVE

To evaluate the anabolic effects of GH, Humatrope (Eli Lilly, 0.05 mg/kg/day) was administered to five children with CF (3 males/2 females) for an average period of 2 years.

METHODS

All patients were maintained on caloric intake of 1.3-2.0 times the recommended daily allowance. Patients underwent standard growth hormone (GH) stimulation studies and measurement of IGF-1 and IGFBP-3.

RESULTS

The mean +/- SE for age and skeletal age were 3.2 +/- 0.85 years and 2.0 +/- 0.45 years, respectively. Growth was assessed by determining both weight and height, which were normalized for age and sex by calculating Z scores using HANES I reference data. Differences in Z scores between clinic visits (delta Z) were calculated for both weight and height to determine changes in growth velocity. The mean Z scores for weight and height were markedly attenuated in CF children as compared with healthy children (-1.95 +/- 0.23 and -2.8 +/- 0.27, respectively). The mean +/- SE for maximum stimulated GH value, IGF-1 and IGFBP-3 were 9.2 +/- 1.2 ng/dl, 67 +/- 6 ng/ml, and 1.7 +/- 0.22 mg/L, respectively. GH treatment improved weight and height Z scores (-0.11 +/- 0.05 and -0.94 +/- 0.18, p < 0.01) significantly. The delta Z scores for weight and height were significantly increased during first and second year of GH treatment (p < 0.02). Also, the average values of IGF-1 and IGFBP-3 were significantly increased as compared to pretreatment values (186 +/- 37 ng/ml and 3.0 +/- 0.22 mg/L, p < 0.01).

CONCLUSIONS

GH treatment significantly improves weight and linear growth in young patients with CF. These data suggest that anabolic effects of GH may be beneficial for treatment of malnutrition in children with CF.

The effect of recombinant growth hormone on nitrogen balance in malnourished patients after major abdominal surgery

The effect of recombinant growth hormone (rGH) on nitrogen balance was studied in malnourished patients receiving total parenteral nutrition after major abdominal surgery. Fifteen patients were randomized to receive either subcutaneous rGH (0.2 iu/kg) or placebo (saline) injection daily for seven days after surgery. Positive nitrogen balance was achieved throughout the treatment period with rGH administration and was significant on days 3 and 6. This was associated with increase in mid-arm muscle circumference and significant weight gain. Plasma insulin-like growth factor-1 (IGF-1) concentration was significantly raised in the rGH group at day 7, suggesting its role in the anabolic effect of growth hormone. Plasma pre-albumin and retinol-binding protein concentrations were raised in both the rGH and control groups, indicating improvement in the nutritional status. We conclude that the postoperative catabolic response can be attenuated using recombinant growth hormone.

Recent advances in hGH clinical research

While hundreds of studies are currently being conducted with growth factors in a variety of areas, there are at least four major areas where significant contributions to medicine and health care of individuals can be accomplished in the future. These areas include the establishment of true benefit and risk for longterm use of hGH therapy for the treatment of short stature in a variety of conditions. They include the identification of medical need for replacement therapy in adults with growth hormone deficiency. The possibility that growth hormone may significantly improve recovery in patients from serious wounds, malnutrition or catabolic states remains to be proven. Finally, the effect of growth hormone therapy on other body systems, such as the reproductive system, the immune system, or bone, is only beginning to be delineated. Clinical investigators are encouraged to maximize their research efforts through well designed and well controlled studies in their areas of interest.

The effect of perioperative exogenous growth hormone on wound bursting strength in normal and malnourished rats

Patients with significant malnutrition secondary to underlying disease may require major surgical intervention on an urgent basis. Nutritional restoration using enteral or intravenous alimentation requires a delay of 10 to 14 days and is frequently not practical. With the availability of human growth hormone (GH) produced by recombinant DNA technology, this study was undertaken to evaluate the effect of exogenous GH on wound tensile strength in a rat model. Fifty-four animals were divided into three groups: group I, normal nourished control; group II, malnourished; group III, malnourished, rat GH treated (1 mg GH administered 3 days preoperative and 5 days postoperative celiotomy). Wound tensile strength was measured at 6 days postoperatively. Wound strengths in malnourished rats were significantly less than in normal controls (P less than .001). With the administration of growth hormone in group III, wound strength was significantly improved when slightly improved over normally nourished controls (P less than .05). A dose response curve demonstrated progressive improvement in wound tensile strength from 0.01 mg/d to 1.0 mg/d. Thus growth hormone administration to malnourished animals significantly enhances wound strength. With the availability of recombinant produced human GH these observations may be clinically applicable.

Low-dose growth hormone and hypocaloric nutrition attenuate the protein-catabolic response after major operation

To determine the effects of low-dose recombinant human growth hormone (GH) and hypocaloric nutrition on postoperative convalescence, we performed a placebo-controlled randomized double-blind trial in 18 patients after elective gastrectomy or colectomy. The subjects received parenteral nutrition containing 20 calories/kg per day and 1 g protein/kg per day. Daily injections of drug or placebo were given during the first postoperative week. The nine control subjects lost 3.3 kg (5.9% of preoperative weight) and had a cumulative nitrogen loss of 32.6 +/- 4.2 g nitrogen at eight days. The patients receiving GH lost significantly less weight (1.3 kg) and nitrogen loss was 7.1 +/- 3.1 g at eight days (p less than 0.001). Kinetic studies demonstrated that the anabolic effects of GH were associated with increased protein synthesis, and amino acid flux studies across the forearm revealed increased uptake of amino acid nitrogen in the GH-treated patients. Body compositional analysis revealed that the patients receiving GH maintained their lean body mass despite the major surgical procedure. Analysis of hand grip force showed a 10% loss of strength in the control subjects; with GH the patients maintained their grip force throughout the postoperative period. We conclude that the postoperative catabolic response can be modified with GH and hypocaloric nutrition. These metabolic and physiologic effects should now be studied in a larger number of patients to determine if this approach can reduce morbidity, mortality, and length of hospital stay for surgical patients.