Johan Verhelst

Hyperprolactinemia: pathophysiology and management.

Hyperprolactinemia is commonly found in both female and male patients with abnormal sexual and/or reproductive function or with galactorrhea. If serum prolactin levels are above 200 microg/L, a prolactin-secreting pituitary adenoma (prolactinoma) is the underlying cause, but if levels are lower, differential diagnoses include the intake of various drugs, compression of the pituitary stalk by other pathology, hypothyroidism, renal failure, cirrhosis, chest wall lesions, or idiopathic hyperprolactinemia. When a pituitary tumor is present, patients often have pressure symptoms in addition to endocrine dysfunction, such as headaches, visual field defects, or cranial nerve deficits. The large majority of patients with prolactinomas, both micro- and macroprolactinomas, can be successfully treated with dopaminergic drugs as first-line treatment, with normalization of prolactin secretion and gonadal function, and with significant tumor shrinkage in a high percentage of cases. Surgical resection of the prolactinoma is the option for patients who may refuse or do not respond to long-term pharmacological therapy. Radiotherapy and/or estrogens are also reasonable choices if surgery fails. In patients with asymptomatic microprolactinoma no treatment needs to be given and a regular follow-up with serial prolactin measurements and pituitary imaging should be organized. Currently, the most commonly used dopamine agonists are bromocriptine, pergolide, quinagolide and cabergoline. When comparing the plasma half-life, efficacy and tolerability of these drugs, cabergoline seems to have the most favorable profile, followed by quinagolide. Ifprolactin levels are well controlled with dopamine agonist therapy, gradual tapering of the dose to the lowest effective amount is recommended, and in a number of cases medication can be stopped after several years. Evidence to date suggests that cabergoline and quinagolide appear to have a good safety profile for women who wish to conceive, but hard evidence proving that dopamine agonists do not provoke congenital malformations when taken during early pregnancy is currently only available for bromocriptine. Once pregnant, dopamine agonist therapy should be immediately stopped, unless growth of a macroprolactinoma is likely or pressure symptoms occur. At our institution patients with symptomatic prolactinomas, both micro- and macroadenomas, are treated with cabergoline as the first-line aproach. In the small group of patients who do not respond to this treatment, or who refuse long-term therapy, surgery is offered. Radiotherapy is given if both pharmacologic therapy and surgery fail.

Two years of replacement therapy in adults with growth hormone deficiency

Although several studies have shown beneficial short‐term effects of recombinant human growth hormone (rhGH) therapy in adult GH deficient (GHD) patients, few data are available on large groups of patients treated for more than one year. In addition, the optimal dose of rhGH for each patient and the baseline parameters that predict which patients will benefit most from therapy or will have adverse events are not entirely elucidated.

Endocrine profiles during administration of the new non-steroidal anti-androgen Casodex in prostate cancer.

OBJECTIVE Casodex (Zeneca) is a new potent, long‐acting non‐steroidal anti‐androgen, which produces androgen deprivation by blocking the androgen receptor. We evaluated the endocrine effects of Casodex 150 mg daily given in monotherapy as primary treatment for patients with prostate cancer.

Clinical Pharmacokinetics of the Antiandrogens and Their Efficacy in Prostate Cancer

Prostatic cancer is the second most common cause of cancer death in males. Treatment by radical prostatectomy and radiotherapy is useful in the early stages of the disease. Whenever metastases occur, patients are usually treated by surgical (orchidectomy) or medical [gonadotropin releasing hormone (GnRH) analogue] castration. This form of treatment is, however, associated with unwanted adverse effects, such as flushing, loss of libido and potency and all patients ultimately escape therapy after a delay of 1 to 2 years. For this reason antiandrogens have been developed as another means of endocrine ablation therapy.Antiandrogens fall in 2 groups of which the first group, the steroidal antiandrogens such as cyproterone acetate (CPA), have a direct blocking effect at the cellular level but also inhibit testosterone production by their additional gestagenic properties blocking gonadotropin secretion. Except in preventing the flare-up associated with the start of GnRH analogue therapy and in reducing flushing, no evidence exist of any superiority for CPA over classical therapy in terms of adverse effects and survival. The second group, the nonsteroidal or ‘pure’ antiandrogens, only block androgens at the cellular level without any central effects.In contrast with other forms of castration, patients on pure antiandrogens as monotherapy preserve their sexual function and potency, at the expense of a slightly inferior androgen blockade and gynecomastia. These latter effects are explained by a compensatory rise in androgens as a result of the blockade at the central level, which weakens the androgen blockade, and by peripheral aromatisation of the increased androgens to oestrogens. In addition, some evidence exist that pure antiandrogens improve survival if combined with other forms of castration as they also inhibit the adrenal androgens, the so-called maximal androgen blockade (MAB). If patients escape control under MAB, a trial of stopping the antiandrogen must always be considered, as some tumours have ‘learned’ to be activated by these drugs.At the moment it is not yet clear if antiandrogens are of any benefit in downstaging the extent of disease before prostatectomy and/or radiotherapy. Of the currently known pure antiandrogens, bicalutamide offers some advantages over flutamide as it possesses a much longer half-life, allowing a once daily regimen, and has advantages over nilutamide in terms of fewer adverse effects.

Long-Term Growth Hormone Replacement Therapy in Hypopituitary Adults

Growth hormone deficiency (GHD) in the adult has now been fully recognised as a clinical entity characterised by abnormal body composition, osteopenia, impaired quality of life, cardiac dysfunction and an adverse lipid profile. While short-term studies of GH replacement have demonstrated irrefutably a favourable effect on all if not most features of GHD, data on long-term administration spanning more than 2 years are still scarce.Experience of GH replacement up to 5 to 10 years indicate that the beneficial effects on body composition, predominantly a decrease in body fat and an increase in lean mass, is maintained during treatment. Long-term GH therapy also increases muscle strength and exercise performance. All data, with one exception, are consistent with a significant increase in bone mass during prolonged GH therapy. The most distinct effect on bone was observed in the worst affected individuals and in males. Improvement in quality of life is documented shortly after initiation of GH replacement and is maintained during long-term studies. This may explain the reduction in days of sick leave seen during GH therapy. The beneficial effect on cardiovascular risk factors is sustained over a prolonged period of time, revealing a reduction in intima wall thickness, and an improvement in serum lipid levels and clotting parameters. The increase in lipoprotein(a) levels with GH therapy in some studies may be disturbing, but difficulties in measuring this parameter and inconsistencies between the different studies makes it difficult to estimate its real impact. No data are yet available to show that GH replacement will normalise or even improve mortality rate and fracture rate.Adverse events associated with GH replacement therapy are mainly secondary to fluid retention as a result of excess dose administration. This can be adequately prevented by monitoring GH replacement according to serum insulin-like growth factor (IGF)-I levels. From what is currently known, GH replacement does not increase the prevalence of diabetes mellitus, and does not induce new neoplasms or recurrence of the primary brain tumour; however, longer follow-up studies are needed to provide definitive answers.In conclusion, it appears not only that long-term GH replacement therapy in adults with GHD is a procedure that can be safely used, but that GH replacement should be considered as a possible life-long therapy in order to maintain its benefits.

Prevalence and characteristics of the metabolic syndrome in 2479 hypopituitary patients with adult-onset GH deficiency before GH replacement: a KIMS analysis

OBJECTIVE An increased risk of cardiovascular morbidity and mortality in adult GH deficiency (GHD) may be related to hypopituitarism but also to the presence of the metabolic syndrome (MetS). Our objective was to investigate the characteristics and prevalence of MetS as well as its comorbidities in adult GHD. Design In KIMS (Pfizer International Metabolic Database) 2479 patients with severe adult-onset GHD, naïve to GH replacement, with complete information on all MetS components were found. MetS was defined according to the National Cholesterol Education Programs Adult Treatment Panel III (NCEP) and the International Diabetes Foundation (IDF). METHODS The prevalence of MetS was calculated and compared with previously published data from the normal population. Associations were assessed between background variables, baseline variables, comorbidities, and MetS. RESULTS MetS was present in 43.1% (NCEP) and in 49.1% (IDF) of patients, clearly higher than data from the normal population (20-30%). MetS prevalence was related to age, GHD duration, and body mass index (BMI), but not to GHD severity, extent of hypopituitarism, or etiology of pituitary disease. Adjusted for age, gender, and BMI, patients with MetS had a higher prevalence ratio for diabetes mellitus: 4.65 (95% confidence interval (CI): 3.29-6.58), for cardiovascular morbidity: 1.91 (95% CI: 1.33-2.75), and for cerebrovascular morbidity: 1.77 (95% CI: 1.09-2.87) than patients without MetS. CONCLUSIONS MetS is highly prevalent in GHD and is associated with a higher prevalence ratio for comorbidities. The presence of MetS in GHD may therefore contribute to the increased risk of cardiovascular morbidity and mortality found in these patients.

Incidence of diabetes mellitus and evolution of glucose parameters in growth hormone-deficient subjects during growth hormone replacement therapy: a long-term observational study.

OBJECTIVE Growth hormone (GH) deficiency is associated with insulin resistance and diabetes. The aim of the current study was to determine incidence of diabetes during GH replacement therapy (GHRT) and the effect of GHRT on fasting plasma glucose concentrations and HbA1c in adult patients with GH deficiency. RESEARCH DESIGN AND METHODS A total of 5,143 GH-deficient patients (male 49.9%; mean age ± SD, 49 ± 13 years; BMI 29.1 ± 5.9 kg/m2) were analyzed. Mean observation period was 3.9 years (range 0.01–13). Total number of patient-years was 20,106. Observed number of cases (O) was compared with expected number of cases (E). Reference rates were from Sweden, three additional European regions, and one U.S. region. RESULTS Patients who developed diabetes (n = 523) were older; had higher BMI, waist circumference, triglyceride concentrations, and blood pressure; and had lower HDL-cholesterol concentrations (P < 0.0001) than those who did not develop diabetes. Diabetes incidence was 2.6 per 100 patient-years, equal in both sexes, and significantly increased compared with the Swedish reference (O/E = 6.02; P < 0.0001) as well as with the four other populations (O/E = 2.11–5.22). O/E increased with BMI and decreased with duration of GHRT (P < 0.0001). There was no significant association with GH dose (P = 0.74) or IGF-I SDS (P = 0.47). In subjects not developing diabetes, plasma glucose concentrations increased from 84.4 ± 0.9 mg/dL to 89.5 ± 0.8 mg/dL (0.70 mg/dL/year) and HbA1c increased from 4.74 ± 0.04% to 5.09 ± 0.13% (0.036%/year) after 6 years of GHRT. CONCLUSIONS Diabetes incidence appears to be increased in GH-deficient patients receiving GHRT and exhibiting an adverse risk profile at baseline. Therefore, glucose homeostasis parameters should be monitored carefully in these patients.

Optimalization and cost management of lanreotide-Autogel therapy in acromegaly

BACKGROUND Lanreotide-Autogel is a depot formulation of the somatostatin analog lanreotide used in the treatment of acromegaly. We investigated whether prolonging or shortening the interval between injections would offer any benefit. SUBJECTS AND METHODS The interval was prolonged from once every 4 weeks to once every 6 weeks when patients (n=9) had normal IGF-I and GH concentrations. When patients (n=12) had still elevated IGF-I or GH on the maximal dose of 120 mg every 4 weeks, the interval was shortened to once every 3 weeks. Serum IGF-I and GH were measured after 12 and 24 weeks to allow for dose adaptation. Symptoms and tumor volume were evaluated at baseline and after 36 weeks. RESULTS In seven of the nine subjects with normal IGF-I and GH, the interval could be extended to 6 weeks without loosing efficacy on IGF-I (195 vs 213 microg/l; not significant, NS) and GH concentrations (1.4 vs 1.3 microg/l; NS). The weekly dose could significantly be reduced (from 23.3 to 17.8 mg; P=0.002). In only 1 of the 12 not-controlled patients, reducing the interval to once every 3 weeks induced normalization of IGF-I and GH. CONCLUSION In subjects whose acromegaly is well controlled using lanreotide-Autogel, prolonging the time interval between injections can often be increased 4 to 6 weeks without loss of efficacy, thereby improving the subjects comfort and reducing the cost of treatment. On the other hand, in subjects whose acromegaly is not controlled on a dose of 120 mg every 4 weeks, reducing the interval to every 3 weeks is rarely beneficial.

Cushing's Disease and Hyperprolactinemia Due to a Mixed ACTH- and Prolactin-Secreting Pituitary Macroadenoma

A 36-year-old man with depression, Cushingoid features and hypogonadism was found to have simultaneous pituitary-dependent Cushings disease and marked elevation of serum prolactin (PRL). CT-scan revealed a macroadenoma with suprasellar extension. Transphenoidal surgery cured the patients Cushings disease, but failed to correct his hyperprolactinemia, which was controlled by subsequent bromocriptine therapy. Immunostaining of the pituitary tumor was positive for PRL as well as for ACTH, and ACTH-related peptides beta-lipotropin and beta-endorphin in two distinct tumor cell lines. This pituitary tumor is one of the few mixed PRL- and ACTH-secreting tumors documented by immunostaining. It is the second reported in a macroadenoma, in which PRL-secreting tumoral cells are much more abundant than ACTH-secreting cells.

A giant prolactinoma presenting with unilateral exophthalmos: effect of cabergoline and review of the literature.

We report the case of a 45-year-old male presenting with unilateral exophthalmos due to a large tumoral mass invading the skull base. Ophthalmologic examination did not show any visual field defects. Imaging techniques demonstrated extension of a huge tumor (approx. 8×8×8 cm) into the right orbit and nasopharynx. Endocrine work-up revealed grossly elevated serum prolactin (PRL) levels (26,466 μg/l, nl. <12), pointing to a large, invasive macroprolactinoma. Stimulation tests indicated associated partial adrenal and growth hormone deficiencies. Planned surgery was abandoned, and the patient was instead treated with the long-acting dopamine agonist, cabergoline. Over a period of one year, serum PRL dropped to 131 μg/l, while the tumor mass shrank to less than 50% of its original volume (with 3.5 mg/ week of cabergoline). The exophthalmos disappeared, and the patient did not develop rhinorrhea or any other side effects from treatment with cabergoline. The efficacy was maintained throughout the second year (ultimate serum PRL 74 μg/l, and final size less than 10% of the original). With reference to this case, we review other macroprolactinomas reported in the recent literature for associated exophthalmos, grossly elevated serum PRL levels (≥15,000 μg/l), and/or “giant” size (≥4 cm in maximum diameter). We highlight the use of dopamine agonists in the treatment of prolactinomas with such unusual characteristics.