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Biomedical subjects

Ilan Shimon

Publications and source records attributed to Ilan Shimon.

18 recordsLinked to original sources
PubMed2006

Cortistatin inhibits growth hormone release from human fetal and adenoma pituitary cells and prolactin secretion from cultured prolactinomas.

CONTEXT: Cortistatin (CST) is a neuropeptide that shares high homology with somatostatin and binds with high affinity to all somatostatin receptor (SSTR) subtypes. Many of its endocrine and biological activities overlap with those of somatostatin. OBJECTIVE/DESIGN: The objective of the study was to assess the direct in vitro effects of CST on human pituitary hormone secretion. SETTING: This study was performed in the endocrine laboratory of a tertiary academic medical center. MATERIALS: Primary cell cultures of human fetal (21-25 wk gestation) pituitary tissues and cultured hormone-secreting adenoma cells were used in this study. INTERVENTIONS: Cell cultures were incubated with CST-14 or CST-17, somatostatin, GHRH, SSTR analogs, and ghrelin analogs, and hormone secretion was analyzed. OUTCOME MEASURES: GH and prolactin (PRL) medium concentrations were tested by hormone assay, and SSTR mRNA was tested by RT-PCR. RESULTS: CST-14 (10 nm) inhibited GH secretion by up to 65% in all fetal pituitary specimens after 4-h incubation (P < 0.05). CST-14 or CST-17 (10 nm) inhibited basal GH secretion in six of the 13 GH-cell adenomas and two of the three GH-PRL mixed adenomas. CST-17 (100 nm) suppressed the GH response to GHRH and ghrelin analog (10 nm each) by 30-50% in adenomas (P < 0.05). Three PRL-adenomas treated with CST-17 (10 nm) showed a 20-40% inhibition of PRL release (P < 0.05), whereas in three others no suppression or mild response was achieved at this concentration. A comparable inhibition of PRL secretion was obtained with SSTR5-selective analog but significantly less with SSTR2-preferential compounds. RT-PCR revealed the expression of both SSTR2 and SSTR5 in all GH-cell and mixed adenomas studied and all PRL-secreting adenomas studied, except for two of the CST-resistant prolactinomas, in which SSTR5 was absent. CONCLUSIONS: This is the first report of in vitro CST suppression of human GH and PRL in cultured pituitary tissues. The regulation of PRL release from cultured adenomas appears to be primarily mediated by SSTR5.

Adenoma↗
PubMed2006

Adiponectin, ghrelin, and leptin in cancer cachexia in breast and colon cancer patients.

BACKGROUND: The hormone ghrelin and the adipocytokines leptin and adiponectin participate in body weight regulation. In response to weight loss, ghrelin and adiponectin levels increase and leptin decreases. Cancer cachexia is a complex metabolic state, characterized by loss of muscle mass and adipose tissue together with anorexia. The authors hypothesized that responses of these hormones may be attenuated in cancer cachexia. METHODS: Fasting plasma ghrelin, adiponectin, and leptin levels, as well as weight loss, were determined in 40 cancer patients: 18 of them suffered from cancer-induced cachexia, and 22 served as a comparison group. Hormone levels were measured before administration of cancer therapy. RESULTS: A similar distribution of age, gender, and diagnosis was observed in both study groups, but the cachectic patients had higher rates of metastatic disease and lower albumin levels. No significant correlation was observed between plasma adiponectin levels and weight loss. Mean plasma ghrelin levels were higher among cachectic compared with noncachectic patients. Notably, the association between ghrelin levels and weight loss was only modest, and in a third of the cachectic patients, ghrelin levels were equal to or lower than those in the noncachectic group. Plasma leptin levels showed gender-dependent associations, and significantly lower levels were found among cachectic women but not among cachectic men. CONCLUSIONS: Results suggested a gender-dependent attenuation of expected physiologic responses to weight loss among cancer cachexia patients. Thus, impaired response of adiponectin, ghrelin, and leptin may play a role in the pathogenesis of cancer cachexia syndrome.

Adiponectin↗
PubMed2006

Feedback inhibition of gonadotropins by testosterone in men with hypogonadotropic hypogonadism: comparison to the intact pituitary-testicular axis in primary hypogonadism.

Men with hypogonadotropic hypogonadism (HH) due to hypothalamic-pituitary disease present with low serum testosterone levels combined with undetectable, low, or normal gonadotropin levels. Treatment consists of testosterone replacement to reverse the symptoms of androgen deficiency. The aim of this study was to examine the dynamics and feedback inhibition of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) in relation to testosterone in 38 men with HH treated with testosterone. Findings were compared with 11 men with primary hypergonadism (PH). Testosterone replacement led to a suppression of FSH levels from 2.8 IU/L at baseline to 1.1 IU/L and to a suppression of LH levels from 2.3 to 0.8 IU/L. There was a linear correlation between levels of FSH and LH (after natural log transformation for both) and testosterone levels in both the HH and PH groups. However, the differences in intercepts and slopes between the groups were significant. To determine whether nonsuppressed FSH or LH during testosterone replacement reduces the probability of eugonadism, as reflected by normal testosterone levels, gonadotropin levels were measured and categorized as low (<0.5 IU/L), medium (0.5-2 IU/L), and high levels (>2 IU/L). The higher FSH or LH levels were found to significantly decrease the chance for achieving eugonadism. In conclusion, in men with HH due to hypothalamic-pituitary disease or injury, the pituitary-testicular hormonal axis maintains its physiological negative feedback between testosterone and gonadotropins. Thus, gonadotropin levels in men with HH might be useful, together with testosterone concentrations, for assessing the adequacy of androgen replacement.

Adolescent↗
PubMed2006

Clinical and biochemical stabilization of Nelson's syndrome with long-term low-dose cabergoline treatment.

We report the results of long-term (6-year) treatment of Nelson's syndrome with the long-acting dopamine agonist, cabergoline, in a 55-year-old woman. The disease presented 26 years after bilateral adrenalectomy and radiation treatment for Cushing's disease, followed by glucocorticoid and mineralocorticoid replacement therapy. Signs of Nelson's syndrome included skin and mucosal hyperpigmentation accompanied by elevated plasma levels of adrenocorticotropic hormone (ACTH) (984 pmol/l; normal, 2.0-11.5 pmol/l). Magnetic resonance imaging of the pituitary demonstrated sellar enlargement with a 15 mm macroadenoma. The patient was initially treated with bromocriptine (10 mg/d) which had no effect on either ACTH level or tumor mass. Because of visual loss, transsphenoidal surgery was performed, with partial excision of the adenoma and chiasmal decompression, followed by radiosurgery. However, ACTH levels improved only temporarily, and then increased to previous levels. Therefore, cabergoline treatment (1.5 mg/week) was initiated. ACTH levels decreased dramatically from 1050 to 132 pmol/l, accompanied by clinical improvement. Repeated imaging studies demonstrated a stable residual pituitary tumor. This case demonstrates that long-term cabergoline treatment may be efficient in patients with Nelson's syndrome.

Cabergoline↗
PubMed2006

Melanin-concentrating hormone stimulates human growth hormone secretion: a novel effect of MCH on the hypothalamic-pituitary axis.

Melanin-concentrating hormone (MCH), a 19-amino acid orexigenic (appetite-stimulating) hypothalamic peptide, is an important regulator of energy homeostasis. It is cleaved from its precursor prepro-MCH (ppMCH) along with several other neuropeptides whose roles are not fully defined. Because pituitary hormones such as growth hormone (GH), ACTH, and thyroid-stimulating hormone affect body weight and composition, appetite, insulin sensitivity, and lipoprotein metabolism, we investigated whether MCH exerts direct effects on the human pituitary to regulate energy balance using dispersed human fetal pituitaries (21-22 wk gestation) and cultured GH-secreting adenomas. We found that MCH receptor-1 (MCH-R1), but not MCH receptor-2, is expressed in both normal (fetal and adult) human pituitary tissues and in GH cell adenomas. MCH (10 nM) stimulated GH release from human fetal pituitary cultures by up to 62% during a 4-h incubation (P < 0.05). Interestingly, neuropeptide EI (10 nM), which is also cleaved from ppMCH, increased human GH secretion by up to 124% in fetal pituitaries. A milder, albeit significant, induction of GH secretion by MCH (20%) was seen in cultured GH-secreting pituitary adenomas. A comparable stimulation of GH secretion was seen when cultured mouse pituitary cells were treated with MCH. Treatment of cultured GH adenoma cells with MCH (100 nM) induced extracellular signal-regulated kinases 1 and 2 phosphorylation, suggesting activation of MCH-R1. In aggregate, these data suggest that MCH may regulate pituitary GH secretion and imply a potential cross-talk mechanism between appetite-regulating neuropeptides and pituitary hormones.

Animals↗
PubMed2005

Cell-replacement therapy for diabetes: Generating functional insulin-producing tissue from adult human liver cells.

Shortage in tissue availability from cadaver donors and the need for life-long immunosuppression severely restrict the large-scale application of cell-replacement therapy for diabetic patients. This study suggests the potential use of adult human liver as alternate tissue for autologous beta-cell-replacement therapy. By using pancreatic and duodenal homeobox gene 1 (PDX-1) and soluble factors, we induced a comprehensive developmental shift of adult human liver cells into functional insulin-producing cells. PDX-1-treated human liver cells express insulin, store it in defined granules, and secrete the hormone in a glucose-regulated manner. When transplanted under the renal capsule of diabetic, immunodeficient mice, the cells ameliorated hyperglycemia for prolonged periods of time. Inducing developmental redirection of adult liver offers the potential of a cell-replacement therapy for diabetics by allowing the patient to be the donor of his own insulin-producing tissue.

Adenoviridae↗
PubMed2005

Alendronate for osteoporosis in men with androgen-repleted hypogonadism.

Male hypogonadism is associated with low bone mineral density (BMD) and an increased risk of fractures. Testosterone replacement therapy improves BMD in young hypogonadal men. This effect is milder in older patients, who are at greater risk for fractures. We studied the effects of alendronate or placebo on BMD in 22 osteoporotic men, 29-69 years of age (mean, 50.2+/-11.2 years) with long-standing hypogonadism, receiving standard testosterone replacement treatment. Alendronate 10 mg daily (n=11) increased lumbar-spine BMD by 6.0 and 8.4% at 6 and 12 months, respectively, compared with -0.5% at 6 months and +3.3% at 12 months in the placebo group (n=11; P<0.005). Alendronate also increased mean femoral-neck BMD by 1.9% after 1 year, compared to a 1.4% decrease with placebo (P<0.005), and increased the total body bone mineral content by 4.4%, compared to a 0.6% decrease with placebo (P=0.07). After 6 months alendronate suppressed urinary deoxypyridinoline by 50% (P<0.005), compared to a 24% decrease in the placebo group. Both the alendronate and placebo groups continued with alendronate 70 mg once weekly for the following 2 years. Lumbar-spine BMD during this open-label study phase did not change significantly in the group originally treated with alendronate, but continued to increase in the placebo-alendronate group by 5.4, 6.5, and 6.2% after 18 (6 months of alendronate), 24 and 36 months, respectively (P<0.05). Femoral-neck BMD continued to increase in both groups receiving active therapy; in the alendronate-alendronate group by 3.7, 2.7, and 5.2% after 18, 24, and 36 months, respectively (P=0.01), and in the placebo-alendronate group by 0.7 and 1.9% at 24 (first 12 months of alendronate) and 36 months, respectively (P<0.05). Our results support the long-term administration of alendronate along with testosterone replacement to men with hypogonadism-induced osteoporosis.

Adult↗
PubMed2005

Nitric oxide stimulates growth hormone secretion from human fetal pituitaries and cultured pituitary adenomas.

Nitric oxide (NO), a highly reactive free radical, has been identified as a neurotransmitter in the central and peripheral nervous system. NO synthase (NOS) is the enzyme responsible for NO production from L-arginine and plays an important role in regulating the release of several hypothalamic peptides. In the pituitary, NO was found to increase growth hormone (GH) secretion in several in vitro and in vivomodels. However, its role in human GH regulation is unknown. The aim of this study was to investigate the regulatory effects of NO on human GH and prolactin secretion using primary cell cultures of human fetal pituitaries and cultured hormone-secreting adenomas. Incubation of the human fetal pituitaries (21-24 wk gestation) in the presence of sodium nitroprusside (SNP; 1 mM), a NO donor, for 4 h resulted in a 50-75% increase in GH secretion, similar to the stimulatory effect evoked by growth hormone-releasing hormone (GHRH) (10 nM). However, fetal PRL secretion was not affected by SNP. GH release was also stimulated (40-70% increase) by SNP in 60% of the cultured GH-secreting adenomas studied. SNP-induced GH release was inhibited in both fetal and adenomatous cells by PTI0, a NO scavenger. The addition of cGMP (0.1-1 mM), the second messenger of multiple NO actions, enhanced fetal and adenomatous GH secretion by 55-95%. Neuronal NOS (nNOS) was expressed in normal (fetal and adult) human pituitary tissues and in GH-secreting adenomas. Examination of its functional expression using L-arginine (1 microM) yielded a 35% increase in GH release from cultured GH-secreting adenoma. This response was blocked by a NOS inhibitor with high selectivity for the neuronal enzyme and by a guanylyl cyclase inhibitor. In conclusion, NO stimulates human GH in cultured fetal pituitaries and GH-secreting adenomas. Cyclic GMP is probably involved in this hormonal regulation.

Adenoma↗
PubMed2004

Malignant bronchial carcinoid tumor metastatic to the pituitary in a thyroid carcinoma patient: successful treatment with surgery, radiotherapy and somatostatin analog.

A carcinoid pituitary metastasis is very rare, and is reported scarcely in a few patients. We describe an unusual case of metastatic atypical bronchial carcinoid to the anterior pituitary gland in a 47-year-old male who presented with bitemporal hemianopsia and hypopituitarism. His primary bronchial carcinoid was resected two years previously. Foci of metastatic papillary thyroid carcinoma were also identified in the lung resected for the bronchial carcinoid. He thereby underwent total thyroidectomy followed by radioiodine ablative treatment. Transsphenoidal partial removal of the suprasellar mass was performed, and atypical carcinoid metastasis was identified. He received conventional fractionated sellar radiotherapy, which was supplemented with octreotide (Sandostatin LAR) injections following a positive pituitary uptake on octreotide scan. This treatment suppressed his elevated 5-HIAA urinary excretion to a normal level. His vision has returned to normal and the pituitary mass diminished in size.

Brain↗
PubMed2003

Increased MIB-1/Ki-67 labeling index as a predictor of an aggressive course in a case of prolactinoma.

Secondary resistance to dopamine agonists is a rare phenomenon in patients with a prolactinoma. We describe a 55-year-old male with a macroprolactinoma initially responding favorably to bromocriptine treatment with normalization of prolactin levels and tumor shrinkage. Two years later, he developed resistance to bromocriptine treatment and subsequently to cabergoline. The aggressive course of the disease necessitated three surgical interventions. Staining of the pituitary tissue revealed a very high MIB/Ki-67 labeling index that increased further in specimens derived from repeated surgery. This case demonstrates that high and increasing levels of the MIB/Ki-67 labeling index may indicate an aggressive course associated with secondary dopamine resistance.

Biomarkers, Tumor↗
PubMed2003

Transient elevation of triiodothyronine caused by triiodothyronine autoantibody associated with acute Epstein-Barr-virus infection.

A unique 16-year old female patient presented after acute Epstein-Barr virus (EBV) infection with severe primary hypothyroidism. Her thyroid test results were thyrotropin level (TSH) of 198 mU/L (normal, 0.4-4 mU/L), free thyroxine [FT(4)], 2.5 pmol/L (normal, 10-25 pmol/L), total triiodothyronine (TT(3)) > 19.5 nmol/L (normal, 1.3-2.7 nmol/L), and free triiodothyronine (FT(3)), 0.77 pmol/L (normal, 3.3-6.3 pmol/L). She had high titers of thyroglobulin and thyroid peroxidase autoantibodies. In vitro triiodothyronine (T(3))-binding measured by radioimmunoprecipitation was 86% (normal, up to 8.5%) and thyroxine (T(4))-binding 8.2% (normal, 6.4%). Serum immunoglobulin G (IgG) absorption, achieved by protein-G Sepharose beads, decreased TT(3) toward normal. Levothyroxine treatment normalized the low baseline FT(4) and FT(3) values, and suppressed TSH to normal. However, TT(3) remained highly elevated and returned to normal after 20 months, while T(3 )binding gradually decreased. Thus, her severe hypothyroidism was masked by this unusual phenomenon. Thirty-four patients with EBV infection (15 with acute disease and 19 with previous infection) were tested for thyroid hormone levels. EBV antibodies (early antigen immunoglobulin M [IgM] and IgG and anti-Epstein-Barr virus nuclear antigen [EBNA] IgG) were measured by enzyme-linked immunosorbent assay (ELISA). In 15 patients with acute EBV the mean TT(3) level was 2.47 +/- 0.39 nmol/L (5 had TT(3) values above normal) compared to a mean TT(3) of 1.70 +/- 0.53 nmol/L in 19 subjects with previous infection (p < 0.0005; only 1 had a TT(3) result above normal), with no differences in FT(4) and TSH concentrations between the two groups. Acute EBV infection may be associated with transient mild to severe TT(3) elevation as a result of assay interference by anti-T(3) autoantibodies.

Acute Disease↗
PubMed2003

The cell adhesion molecules N-cadherin and neural cell adhesion molecule regulate human growth hormone: a novel mechanism for regulating pituitary hormone secretion.

Pituitary GH secretion is regulated by hypothalamic hormones and peripheral factors. Cell-cell contact may also have an important role in regulating pituitary hormone expression and secretion. The role of pituicyte cell-cell contact mediated by N-cadherin and neural cell adhesion molecule (N-CAM) was studied in the regulation of GH secretion. RT-PCR showed N-cadherin mRNA expression in eight of 12 of GH-secreting adenomas compared with one of seven of prolactin-cell adenomas. N-cadherin and N-CAM were similarly expressed in adenomas and in adult and fetal normal pituitary tissues. The effects of CAM homophilic binding on GH secretion from dispersed human fetal pituitary cultures were studied by manipulating CAM mediated cell-cell contact using either soluble N-cadherin-Fc or pituitary cells cocultured with NIH-3T3 cells stably expressing CAMs. CAM stimulation increased GH secretion from pituitary fetal cultures by 40-60% (P < 0.05) and also from cultured GH adenoma cells by 40-75% (P < 0.05). Disrupting N-cadherin homophilic binding by anti-N-cadherin antibody decreased fetal, but not tumorous GH secretion by 40% (P < 0.05). This study indicates that pituitary cell-cell contact mediated by homophilic interactions between adhesion molecules regulates human GH secretion.

3T3 Cells↗
PubMed2003

Somatostatin receptors in pituitary and development of somatostatin receptor subtype-selective analogs.

Somatostatin receptor (SSTR) subtypes 1, 2, and 5 are expressed in the normal human pituitary. SSTR2 and SSTR5 are expressed in almost all growth hormone (GH) cell adenomas, and prolactin (PRL)-secreting tumors express SSTR5 more than SSTR2. SSTR4 is not detected in all pituitary adenoma subtypes, and SSTR1 and SSTR3 are expressed in about 50% of tumors. Human GH is regulated through ligand binding to both SSTR2 and SSTR5, but octreotide and lanreotide, the two clinically available somatostatin analogs, bind to human SSTR2 much better than to SSTR5. Novel SSTR2- and SSTR5- selective analogs with improved binding affinity for these receptor subtypes are highly potent in suppressing GH release from cultures of human fetal pituitaries or GH-cell adenomas. Only SSTR5-selective analogs suppress in vitro PRL secretion from cultured prolactinomas. A new SSTR2+5 bispecific analog with high affinity and selectivity for both SSTR2 and SSTR5, and a somatostatin analog with a unique broad receptor (SSTR1, 2, 3, and 5) binding profile, are both able to inhibit in vitro GH release in GH cell adenomas partially sensitive to octreotide. Recently, a somatostatindopamine hybrid molecule was introduced with potentially functional synergy on GH and PRL release. Using the expanding knowledge on SSTRs and their ligand activation, the development of novel pharmacologic concepts may open new opportunities for effective manipulation of this complex intracellular signaling system. These concepts may achieve better control of pituitary hormone hypersecretion, pituitary size, as well as antitumor effects in patients with SSTR-expressing tumors.

Amino Acid Sequence↗
PubMed2003

Growth hormone replacement for adult growth hormone deficiency.

Growth hormone deficiency (GHD) in childhood causes growth retardation, short stature and significant impairment of adult height. Growth hormone (GH) has been given successfully to these children for > 40 years but only since the introduction of recombinant DNA technology, has enough GH been available for paediatric needs and also for other indications. Adults with pituitary disease and hypopituitarism commonly develop GHD. Adult GHD is associated with an array of body composition alterations and metabolic abnormalities, as well as impaired physical performance and psychological well-being. None of these abnormalities are pathogenic for GHD but they constitute a characteristic clinical syndrome. GH substitution for adult GHD has been approved since 1996 in the US and most Western countries and since then, the clinical experience with this novel therapeutic modality is exponentially increased. GH replacement in this population has resulted in considerable clinical benefits. This article reviews the therapeutic principles, available GH formulations and current treatment guidelines for adult patients with GHD.

Body Composition↗
PubMed2002

Elevated insulin-like growth factor-1 and insulin-like growth factor binding protein-2 in malignant pleural effusion.

Insulin-like growth factor-1 (IGF-1) and its binding proteins (IGFBPs) are produced by many tissues and are present in serum and other biological fluids. Alterations in sera of IGF-1 and 2 and IGFBPs were demonstrated in patients with malignancy, infection and other diseases causing pleural effusion. In this study the IGF-1 and IGFBP-2 content and the specific electrophoretic patterns of IGFBPs in samples of sera and pleural effusions of 25 patients with malignancy, infection and congestive heart failure were investigated. IGF-1 levels in exudative effusions of malignant solid tumors were significantly higher [(mean +/- SD), 20.9+/-7.5 nmol/L, n = 9] than in lymphoma (11.0+/-5.2 nmol/L, n = 5; p < 0.05), infection (11.4+/-6.5 nmol/L, n = 6; p < 0.05) and transudative effusion of congestive heart failure (4.3+/-3.3 nmol/L, n = 5; p < 0.02). IGFBP-2 was markedly increased in effusions of malignant solid tumors (2.14+/-0.82 mg/L, n = 9) compared with exudates of lymphoma, infection and transudates (1.10+/-0.70, 1.22+/-0.32 and 0.93+/-0.52 nmol/L, respectively, p < 0.05). Moreover, in effusion of solid tumors, IGFBP-2 levels were higher than those in corresponding sera, which suggests local production of this binding protein. The demonstration of IGFBP-2 in solid tumor cells by immunohistochemistry further supports this possibility. This work demonstrates the existence of the IGF-1/IGFBP system in pleural fluids from different etiologies and implies possible use of IGF-1 and IGFBP-2 as a potential marker of malignant effusions.

Adult↗
PubMed2002

Thyrotropin suppression by thyroid hormone replacement is correlated with thyroxine level normalization in central hypothyroidism.

We have retrospectively studied 41 patients with hypothalamic-pituitary disease and central hypothyroidism associated with hypopituitarism. Sixteen patients had nonsecreting pituitary macroadenoma, whereas different sellar and suprasellar pathologies affected all other patients. Pretreatment thyrotropin (TSH) level (mean +/- standard error of the mean [SEM]) was 2.04 +/- 0.25 mU/L (normal, 0.4-4), and gradually decreased to 0.51 +/- 0.19 mU/L (range, 0.009-3.38) by treatment with levothyroxine in a mean dose of 86 +/- 6 microg/d. TSH was suppressed by thyroid replacement to less than 0.5 mU/L in 80% of patients. Mean baseline free thyroxine (FT4) was 7.55 +/- 0.51 pmol/L (normal, 11.8-24.6) and gradually increased with thyroid hormone to 15.19 +/- 1.0 pmol/L, whereas total thyroxine (TT4) increased from 57.4 +/- 2.6 to 104.4 +/- 5.0 nmol/L (normal, 77-154). Mean pretreatment total triiodothyronine (TT3) was 1.44 +/- 0.09 nmol/L (normal, 1.1-2.7), and was not altered by treatment. Thyrotropin-releasing hormone (TRH) test was performed in 20 patients before thyroid replacement, and mean baseline and peak TSH levels were 1.33 +/- 0.3 and 7.14 +/- 1.62 mU/L, respectively. In 5 subjects TSH was stimulated to 6 mU/L or more, whereas in 5 others TSH was not affected. Based on linear regression of logarithm (Ln) TSH against FT4, a leftward shift of the TSH/FT4 ratio was demonstrated in patients with central hypothyroidism compared to 17 patients with primary hypothyroidism. Plotting measurements of TSH against FT4 for 6 individuals with central hypothyroidism showed different regression slope for each patient. Suppression of TSH by thyroid replacement to levels below 0.1 mU/L predicted euthyroidism in 92% of cases, compared to 34% when TSH was above 1 mU/L (p < 0.0001). In conclusion, in central hypothyroidism baseline TSH is usually within normal values, and is further suppressed by exogenous thyroid hormone as in primary hypothyroidism, but to lower levels. Thus, insufficient replacement may be reflected by inappropriately elevated TSH levels, and may lead to dosage increment.

Adolescent↗
PubMed2002

Transsphenoidal surgery for Cushing's disease: endocrinological follow-up monitoring of 82 patients.

OBJECTIVE: Transsphenoidal surgery is the preferred treatment modality for adrenocorticotropic hormone-secreting pituitary adenomas. In the past 2 decades, several institutions in the United States and Europe have reported remission rates of 70 to 85% after transsphenoidal surgery for treatment of Cushing's disease. We analyzed our postoperative results for a large cohort of patients with Cushing's disease. METHODS: Eighty-two patients with adrenocorticotropic hormone-secreting adenomas (79 microadenomas and 3 macroadenomas) underwent transsphenoidal surgery between 1990 and 2000. Seventy-seven patients were surgically treated for the first time, and 13 patients underwent reoperations (5 had undergone the first operation elsewhere) because of previous surgical failure (10 patients) or recurrence (3 patients). The mean postoperative follow-up period was 4.2 +/- 2.8 years. Biochemical remission was defined as postoperative normalization of elevated 24-hour urinary free cortisol secretion and suppression of morning cortisol levels with 1 mg of dexamethasone. RESULTS: Remission was achieved for 78% of all patients after one operation and for 62% of patients who underwent a second operation. The recurrence rate was 5%. Ten patients did not exhibit a visible tumor on magnetic resonance imaging scans, and the other patients were divided according to adenoma size (2-5 or 6-10 mm). Remission rates were similar for the three groups of patients (78-80%). Pituitary tumor stained for adrenocorticotropic hormone was detected in 78% of resected pituitary tissue specimens obtained from patients who achieved remission, compared with 53% from patients who experienced surgical failure (P = 0.06). CONCLUSION: Our series demonstrates the efficacy of transsphenoidal surgery for Cushing's disease resulting from pituitary microadenomas. Microadenoma size had no effect on the remission rate. Reoperations are indicated after initial surgical failures.

Adenoma↗