Faculty Bibliography

Growth hormone (GH) deficiency should he suspected in adults with either hypothalamic or pituitary disease, a history of pituitary or whole brain radiation, or a history of GH treatment during childhood. Clinical manifestations include abnormal body composition (increased fat, decreased lean mass, and lo iv bone density), reduced exercise ca pacity, and unfavorable lipid profile thigh total and LDL cholesterol, low HDL). Although some GH-deficient adults are asymptomatic, others have nonspecific complaints of fatigue, low energy level, and impairment of memory and concentration. The diagnosis of GH deficiency should be confirmed by at least one provocative test. We define GH deficiency as the failure of GH to rise above 3 ng/mL in response to an appropriate stimulus, such as insulin-induced hypoglycemia, L-dopa, or arginine. GH replacement should be reserved for patients with documented GI-I deficiency who show no evidence of active malignancy and do not have severe edema or a history of carpal tunnel syndrome. GI-I treatment of the GH-deficient adult has been shown to have positive effects on body composition, exercise tolerance, and lipids. In nine placebo controlled studies in 392 adults using GH doses ranging between 2.6 and 26 mu g per kg per day, mean body fat decreased 4.4% and mean lean body mass increased 3.4 kp. These changes were seen after 6 months. increase in hip and spine bone mineral density required longer periods of treatment. GH replacement also has been found to increase maximal oxygen consumption, exercise capacity, ventricular ejection fraction, and cardiac output. Improvement in muscle strength has not been demonstrated convincingly, Most studies have shown reduction in total and LDL cholesterol and either increased or unchanged I-IDL, GH's effects on psychological parameters have been difficult to evaluate and require further study Adverse effects, which are more frequent in patients treated with higher doses of GH, include edema of the hands and feet, arthralgias, myalgias, and paresthesias of the fingers. These problems diminish or resolve with dose reduction. In conclusion, GH deficiency in adulthood is recognized as a syndrome that may benefit from treatment. GH replacement should, therefore, be considered in individuals with hypothalamic-pituitary disease who have an abnormal GH response during at least one provocative test. Additional studies are needed to determine the consequences of long-standing GH deficiency and whether the beneficial effects observed during the first 18 months of GH replacement diminish, plateau, or continue to improve during chronic treatment

To study the effects of androgen replacement therapy on muscle mass and strength and bone turnover markers in hypogonadal men, we administered sublingual testosterone (T) cyclodextrin (SLT; 5 mg, three times daily) to 67 hypogonadal men (baseline serum T, < 8.4 nmol/L) recruited from 4 centers in the U.S.: Torrance (n = 34), Durham (n = 12), New York (n = 9), and Salem (n = 12). Subjects who had received prior T therapy were withdrawn from injections for at least 6 weeks and from oral therapy for 4 weeks. Body composition, muscle strength, and serum and urinary bone turnover markers were measured before and after 6 months of SLT. We have shown previously that this regimen for 60 days will maintain adequate serum T levels and restore sexual function. Total body (P = 0.0104) and lean body mass (P = 0.007) increased with SLT treatment in the 34 subjects in whom body composition was assessed. There was no significant change in total body fat or percent fat. The increase in lean body mass was mainly in the legs; the right leg lean mass increased from 8.9 +/- 0.3 kg at 0 months to 9.2 +/- 0.3 kg at 6 months (P = 0.0008). This increase in leg lean mass was associated with increased leg muscle strength, assessed by leg press (0 months, 139.0 +/- 4.0 kg; 6 months, 147.7 +/- 4.2 kg; P = 0.0038). SLT replacement in hypogonadal men led to small, but significant, decreases in serum Ca (P = 0.0029) and the urinary calcium/creatinine ratio (P = 0.0066), which were associated with increases in serum PTH (P = 0.0001). At baseline, the urinary type I collagen-cross linked N-telopeptides/creatinine ratio [75.6 +/- 7.9 nmol bone collagen equivalents (BCE/mmol] was twice the normal adult male mean (41.0 +/- 3.6 nmol BCE/mmol) and was significantly decreased in response to SLT treatment at 6 months (68.2 +/- 7.7 nmol BCE/mmol; P = 0.0304) without significant changes in urinary creatinine. Serum skeletal alkaline phosphatase did not change. In addition, SLT replacement caused significant increases in serum osteocalcin (P = 0.0001) and type I procollagen (P = 0.0012). Bone mineral density did not change during the 6 months of SLT treatment. We conclude that SLT replacement therapy resulted in increases in lean muscle mass and muscle strength. Like estrogen replacement in hypogonadal postmenopausal females, androgen replacement therapy led to decreased bone resorption and urinary calcium excretion. Moreover, androgen replacement therapy may have the additional benefit of increasing bone formation. A longer term study for several years duration would be necessary to demonstrate whether these changes in bone turnover marker levels will result in increased bone mineral density decreased fracture risks, and reduced frailty in hypogonadal men

One hundred and three acromegalic patients from 14 medical centers were enrolled in this study to determine the efficacy and safety of the somatostatin analog, octreotide acetate, during long term treatment. Seventy percent of the patients had undergone previous surgery or radiation treatment. Octreotide was initiated at a dose of 100 micrograms, sc, every 8 h and gradually increased to a maximum of 1500 micrograms daily depending upon the individual patient's clinical and biochemical response [GH and insulin-like growth factor I (IGF-I) reduction]. The mean duration of treatment was 24 months (range, 3-30 months). However, most patients were treated for a mean of 30 months, because this study took place after an initial 6-month study previously reported. Mean serum GH fell from 30.9 micrograms/L (range, 2.7-350) to 5.7 micrograms/L (range, 0.6-59) at the 3 months visit and remained suppressed (P < 0.001). Plasma IGF-I concentrations were also significantly reduced and remained in the normal range for at least half of the treatment visits in 56 of 87 patients (64%) treated for 12-30 months. Patients with higher initial GH concentrations were less likely to normalize IGF-I concentrations during treatment (P < 0.001). There was no evidence of drug tachyphylaxis in those patients who continued taking stable doses of medication. With some exceptions, dose increments above 800 micrograms daily in 31 patients did not provide additional benefit in terms of GH and IGF-I reduction. Headache, excessive perspiration, fatigue, and joint pain were ameliorated in 83-95% of patients. Mean finger circumference was decreased significantly at the 12 month visit (P < 0.05). The most common adverse events reported were diarrhea, abdominal discomfort, loose stools, and nausea; these symptoms usually disappeared within 3 months of treatment. Five patients discontinued octreotide because of adverse events. Of 102 patients with normal baseline ultrasound examinations of the gallbladder, 24 patients (23.5%) developed gallstones (usually during the first year of treatment), and 21 patients developed sludge alone. Gallstone formation was not related to the dose of octreotide. Most patients with cholelithiasis were asymptomatic, and none developed cholecystitis. These observations suggest that octreotide is a valuable long term medical treatment for acromegaly

Growth hormone (GH) plays a role in regulating growth and differentiation of immature glandular structures in the mammary gland, but the mechanisms by which the hormone exerts these effects are unknown. We have previously found that GH stimulates insulin-like growth factor I (IGF-I) I mRNA production within the mammary glands of hypophysectomized rats. In this study we set out to determine if IGF-I administration could mimic the action of GH in initiating mammary gland differentiation and development. Two forms of IGF-I, intact and amino-terminally shortened [des-(1-3)-IGF-I], were found to induce the development of terminal end buds and the formation of alveolar structures in the mammary glands of hypophysectomized, castrated, and estradiol-treated sexually immature male rats. The effect of both forms of IGF-I was similar to that obtained with human GH, but the truncated form was at least 5 times more potent than intact IGF-I. These findings suggest that the inductive effect of GH on glandular differentiation is mediated by the GH-induced production of IGF-I or a related molecule within the mammary gland itself

In contrast to established dogma that PRL is central in mammary development, and GH mimics PRL in affecting growth because of structural similarities, we found that both hGH, which is lactogenic, and rGH, which is non-lactogenic, were significantly more potent than hPRL and rPRL in stimulating mammary growth in rats. Additionally, hGH was more potent than hPRL in increasing mammary IGF-I mRNA content. These data indicate that GH has separate effects on parameters of mammary gland growth, suggesting an independent role for GH in mammary growth

CV 205-502 (Sandoz), an octahydrobenzol [g]quinoline, is a long-acting dopamine agonist which inhibits prolactin secretion. We conducted a phase 2 clinical study in 10 hyperprolactinaemic women (nine of whom were previously intolerant of bromocriptine) in order to determine (1) the dose at which CV 205-502 exerted its prolactin-lowering effect; (2) the nature of adverse reactions associated with long-term therapy; and (3) whether patients who were intolerant of bromocriptine could tolerate CV 205-502. At first patients were randomized to take initial doses of either 0.02 or 0.05 mg daily at bedtime. Thereafter these doses of medication were gradually increased either to the point of normalizing serum prolactin (to 0.70 IU/l or 20 ng/ml) or to a maximum dose of 0.14 mg daily. The lower initial dose was ineffective and had to be increased in all patients. The higher initial dose (0.05 mg) normalized prolactin in three of five women within 24 h. During chronic administration of the final dose of CV 205-502 (mean 0.09 mg a day), serum prolactin decreased from a mean level of 9.19 +/- 4.9 (SEM) IU/l to a mean level of 1.55 +/- 0.49 IU/l (n = 10 patients). Prolactin was normalized in five patients. Two patients, one of whom had been previously unresponsive to bromocriptine, and another unresponsive to pergolide with regard to prolactin inhibition, were also unresponsive to CV 205-502. Nausea, the side-effect responsible for these patients' previous intolerance of bromocriptine, occurred in six of 10 patients taking CV 205-502 but was much less disabling and did not cause any of the patients to stop this medication. Only one patient taking CV 205-502 discontinued treatment because of adverse effects (light-headedness)

To determine whether the human pituitary contains a previously unidentified, nonprolactin (non-hPRL), non-growth-hormone (non-hGH) factor capable of stimulating mammary development, we tested the effects of whole human pituitary extract (hPE) and pituitary extracts depleted of hPRL and hGH ('stripped hPE') in hypophysectomized, castrated estradiol (E2)-treated male rats and rhesus monkeys. Both whole and stripped hPE significantly stimulated rat mammary development (mean scores = 3.3 and 2.0, respectively, on a scale ranging from 0 to 4) in comparison with controls (mean score = 1.0). Mammary development was not due to minute concentrations of hGH or hPRL remaining in stripped hPE because 30- to 100-fold higher concentrations of hGH (Genentech) and 1000-fold higher concentrations of hPRL were required to stimulate significant mammary development. Non-pituitary extracts of human ovary, muscle, and serum, and bovine serum albumin did not stimulate rat mammary gland growth. Trypsin destroyed the mammary mitogenic activity of whole hPE, indicating that the unidentified factor is likely a protein. Mammary growth and development were also stimulated in hypophysectomized, E2-treated monkeys by stripped hPE (mean histological score = 3.25 vs. 1.35 in control animals). Monkeys receiving stripped hPE had undetectable levels of hGH and hPRL in serum sampled over a 24-hr period. These findings suggest that the human pituitary contains a non-hPRL, non-hGH factor that stimulates mammary growth and may be important in normal mammary growth and development and perhaps in breast cancer