Pituitary deficiency in patients with pituitary tumours.
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Acromegaly↗
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Results for “Pituitary Function Tests”
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Hypokalaemia occurring during insulin-induced hypoglycaemia.
Insulin-induced hypoglycaemia was used to test pituitary function in six patients with suspected pituitary deficiency. In each, a fall in serum potassium concentration of from 0-63 to 1-48 mEq/litre (mean fall 1-10 mEq/litre +/- 0-30 SEM) was observed during the two hour period following administration of 1-15 units of insulin per kilogram body weight. In several patients the resulting hypokalaemia was at a level which has been associated with cardiac complications.
Adolescent↗
Long-term insulin-dependent diabetes mellitus with secondary pituitary insufficiency and regression of retinopathy.
Three women with insulin-dependent diabetes mellitus (IDDM) from childhood and early development of diabetic retinopathy are described. Insulin requirement was reduced to 5-12 IU daily in all three after relatively uncomplicated births and all had very brittle diabetes on this dosage. At re-examination 16-22 years after these births and after 34-42 years of IDDM, regression of retinopathy was observed in two patients, while the third had a light retinopathy at the same level as initially. Other diabetic complications were few and none of the patients had nephropathy. Pituitary examination revealed incomplete hypopituitarism in all cases, human growth hormone (HGH) being the sole common factor lacking. These findings and a review of four similar cases reported previously lend some support to the hypothesis of HGH as a possible pathogenetic co-determinant in the development of diabetic retinopathy.
Adult↗
The effect of yttrium-90 implantation on endocrine function and visual fields in patients with "functionless" pituitary tumors, with biopsy and radiological findings.
Thirty patients with symptoms from "functionless" pituitary tumours were treated by yttrium-90 implants, and we report here the effects on symptoms, pituitary function and visual fields. On biopsy, about a third of the tumours showed some hormone granules. In the sixteen fully assessed at 1 year, pituitary function was improved in 25%, unchanged in 62-5%, and reduced in 12-5%. Improvement was confined to those in whom gonadotrophin secretion was the only function impaired pre-implant. Visual field defects were present pre-implant in ten patients (twenty eyes); at 1 year post-implant these defects had lessened in 80% and deteriorated in only 5% of eyes. Subsequently, within 5 years of the implant the field defects had worsened or recurred in four patients, all with initially extensive suprasellar projection; further treatment was then given. Remineralization of the sella was seen after implantation in seven cases, with reduction in fossa size in five. Thus pituitary implantation appears to be a practicable and reasonably simple procedure suitable for the treatment of most cases of "functionless" pituitary tumour. The "supressive" doses of irradiation used are adequate to shrink most tumours without loss of pituitary function.
Adenoma↗
Coexisting primary empty sella syndrome and acromegally.
The 'empty' sells syndrome is now a more frequent diagnosis due to the increased use of pneumoencephalography in the evaluation of the enlarged pituitary fossa. This syndrome has also been classified into a 'primary' form in which there has been no prior pituitary irradiation or surgery, and a 'secondary' form in which the empty sella is found after such procedures. Most patients with the primary empty sella syndrome are found to have normal pituitary function while about 30% have varying degrees of hypopituitarism (Neelon et al., 1973). It is not widely appreciated, however, that the primary empty sella may harbour a pituitary tumour with resultant acromegaly. In this report we describe two such patients who presented with active acromegaly. This entity of pituitary tumour in a primary empty sella merits careful consideration since the coexistence of these two findings may influence the therapeutic approach that might otherwise be appropriate for the pituitary tumour.
Acromegaly↗
Domperidone: a novel agent for the investigation of anterior pituitary function and control in man.
Administration of the novel agent domperidone (10 mg iv), which combines the properties of specific dopamine receptor blockade and inability to cross the blood-brain barrier, leads to acute and significant TSH and PRL release in man. This suggests that the in vivo site of action of endogenous dopamine in the inhibitory control of these two hormones is either the anterior pituitary or median eminence, since these tissues lie outside the blood-brain barrier. This class of drug is of potential value both clinically and experimentally in the investigation of anterior pituitary control mechanisms.
Autoimmune Diseases↗
Effects of cimetidine on pituitary function: Alterations in hormone secretion profiles.
Cimetidine, an H2 receptor antagonist, was given for 6 weeks to six normal male volunteers to study the effects on pituitary, adrenal, thyroid, and testicular hormone secretion. Patients were studied before (day 1) and after (day 42) cimetidine (300 mg four times daily) therapy, and four of the six were restudied after discontinuing cimetidine for 1 month (day 72). Basal TSH concentrations and responses to TRH administration as well as T3 RIA and T4 resin uptakes did not change during or after cimetidine therapy. The diurnal rhythm of plasma cortisol and maximum cortisol response to insulin (0.15 u/kg) were similar on days 1 and 42, but urinary free cortisol excretion fell 31% (Pless than 0.01). Response of GH to exercise, 100 g carbohydrate ingestion and insulin were unchanged, but mean nocturnal GH secretion decreased 33% (P less than 0.025) on cimetidine, and returned to baseline on day 72. The 24-h plasma prolactin profile was unchanged as was the prolactin response to insulin and TRH stimulation. Plasma FSH was not altered, but mean LH concentrations decreased 20% on cimetidine and continued to decline (45% of day 1 levels) after discontinuation of cimetidine (P less than 0.01). Spontaneous LH pulse amplitude declined slightly on day 42, but became significantly lower on day 72 (P less than 0.05). Peak LH responses t gonadotropin-releasing hormone were also reduced on cimetidine therapy (P less than 0.02). Plasma testosterone concentrations did not change but plasma oestradiol concentrations were 38% lower (P less than 0.025) after cimetidine was discontinued. H2 histamine receptors are involved in the control of multiple hormone secretory patterns and blockade of these receptors by cimetidine alters hormone profiles. These changed patterns have to be considered in the interpretation of hormone measurements in patients receiving cimetidine therapy.
Adult↗
Treatment of acromegaly by trans-sphenoidal operation, 90-yttrium implantation and bromocriptine: results in 230 patients.
Two hundred and thirty patients with acromegaly were diagnosed and treated in a prospective cooperative study in twelve university clinics. Primary treatment was: trans-sphenoidal surgery (152 patients), trans-sphenoidal surgery with additional cryotherapy (eighteen patients), Yttrium-90-implantation (thirty patients), bromocriptine (thirty patients). The results of endocrine assessment before treatment and 6 months after operation, 90-Y implantation or commencement of bromocriptine therapy are reported. The best results (low GH, no or little deterioration of pituitary function, low complication rate) were achieved by trans-sphenoidal surgery, especially in patients with intrasellar tumours (basal GH less than 5 ng/ml in 59.7%). Results were less good with increasing tumour size. Additional cryosurgery was accompanied by a high rate of anterior pituitary insufficiency and is no longer employed. Yttrium-90-implantation resulted in less improvement in GH levels (basal GH less than 5 ng/ml in 51.7% of patients with intrasellar tumours), a high rate of pituitary insufficiency and more complications. Bromocriptine treatment was least effective in lowering GH concentrations (basal GH less than 5 ng/ml in 33% of patients with intrasellar tumours). Different criteria for treatment success were compared. In the entire group, basal GH concentrations below 5 ng/ml were attained in 51.7% of all patients whose values were higher than this prior to treatment. Suppressibility of GH below 2 ng/ml during glucose loading occurred in only 34.9%. An abnormal GH response to TRH/LHRH was present in 47.2% before and in 43.4% after/during treatment. The prognostic significance of this latter finding must be evaluated by further study.
Acromegaly↗
A case of 'essential' hypernatraemia due to resetting of the osmostat.
We describe a 24-year-old short, obese girl who has bizarre episodic neurological abnormalities related to hyperosmolality due to hypernatraemia. Investigation of osmoregulation by water loading and infusion of hypertonic saline revealed (i) hypodipsia with thirst onset raised to plasma osmolality of 332 mmol/kg and (ii) elevation of the threshold for vasopressin release (plasma osmolality 320 mmol/kg) but normal slope of the plasma vasopressin-plasma osmolality curve. Baroregulated vasopressin release was also grossly subnormal. Other hypothalamo-pituitary investigations showed deficiencies of releasing hormones for gonadotrophins and growth hormone, but prolactin response to combined hypoglycaemia and TRH was blunted She demonstrated other anomalies including hyperlipoproteinaemia and defective lymph drainage of the legs. Skull X-rays, together with computerized tomography and nuclear magnetic resonance scans of the hypothalamo-pituitary region and the rest of the brain were normal. We believe that this is the first case of essential hypernatraemia documented with direct evidence of resetting of the osmostat.
Adult↗
Studies of hypothalamic pituitary structure and function in patients previously treated with bilateral adrenalectomy alone for Cushing's disease.
A controversy still exists in regard to hypothalamic pituitary function long-term after cure of hypercortisolism due to Cushing's disease. In an attempt to resolve this controversy, we have studied 15 patients, treated at least 6 years previously, by bilateral adrenalectomy. None of these patients had had pituitary-directed therapy. The maximum increment response of serum TSH in response to TRH was greater than 5 mU/l in 13 of the 15. Serum PRL response to TRH, GH response to insulin-induced hypoglycaemia, gonadotrophin responses to LHRH and nocturnal PRL secretion were normal in all patients studied. When nocturnal GH secretion was corrected for age, body mass index and menopausal status it was definitely abnormal in only two patients. The mean nocturnal GH secretion did not differ from that measured in a control group of Addisonian patients. The series of patients also did not differ significantly from the Addisonian patients in relation to the pattern of changes in plasma ACTH, over 24 h after an 0800 h oral dose of hydrocortisone. There was a significant rise in plasma ACTH between 2200 h and 0600 h in both groups of patients. The plasma ACTH concentrations were significantly higher in post-adrenalectomy patients. Hypothalamic pituitary function is normal in the long-term in the majority of patients treated by bilateral adrenalectomy for Cushing's disease.
Adrenalectomy↗
The pituitary megatest: outdated?
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Adrenocorticotropic Hormone↗
Idiopathic central diabetes insipidus in children and young adults is commonly associated with vasopressin-cell antibodies and markers of autoimmunity.
OBJECTIVES: Autoimmune targeting of hypothalamic-neurohypophyseal structures in children and young adults with posterior pituitary and anterior pituitary dysfunction, as well as pituitary stalk involvement, are not yet completely understood. DESIGN: We aimed to (1) evaluate the presence of circulating vasopressin-cell autoantibodies (AVPc-Abs) in young patients with central diabetes insipidus (CDI), (2) detect organ-specific autoantibodies as markers of autoimmunity, and (3) define the relationship between immune markers and neuroimaging findings. PATIENTS: Twenty patients were evaluated at a median age of 16.3 years. Twelve patients had idiopathic CDI, six had Langerhans cell histiocytosis (LCH) and two had germinoma. AVPc-Abs were evaluated in 40 healthy children. Magnetic resonance imaging (MRI) of the hypothalamic-pituitary region was performed longitudinally in all subjects. MEASUREMENTS: Circulating arginine vasopressin (AVP), protein tyrosine phosphatase (IA2), glutamic acid decarboxylase (GAD), 21-hydroxylase (21-OH), endomysium antibodies (EMA), parietal cell (PCA), thyroid peroxidase (TPO), thyroglobulin (TG) and TSH-receptor (TSHr) autoantibodies were evaluated. RESULTS: Circulating AVPc-Abs were found in 15 patients (75%), nine with idiopathic CDI, four with LCH and two with germinoma; the pituitary stalk was involved in most of them. Five patients with idiopathic CDI showed a persistence of AVPc-Abs during follow-up and one became positive subsequently. Serum IA2 autoantibodies were demonstrated in 14 patients (70%) and 21-OH autoantibodies in three of them. CONCLUSION: In idiopathic CDI, circulating AVPc-Abs suggest an autoimmune involvement of the neurohypophyseal system. The identification of AVPc-Abs in subjects who could have either idiopathic CDI or LCH or germinoma, however, indicates that AVPc-Abs cannot be considered a completely reliable marker of autoimmune CDI. Thus, close clinical and MRI follow-up are needed because AVPc-Abs may mask germinoma or LCH.
Adolescent↗
Effect of late hypothalamo-pituitary disconnection on the development of the HPA axis in the ovine fetus and the initiation of parturition.
The studies of Liggins et al. (1) in which fetuses stalk-sectioned from day 116 onwards delivered at or near term, suggested that a connection between the fetal hypothalamus and pituitary is not essential for parturition to occur. The objective of this study was to repeat these experiments on the effects of pituitary stalk sections at different gestational ages and include information on the plasma concentrations of key fetal hormones. We have used the more sophisticated technique of hypothalamo-pituitary disconnection (HPD) at either of two gestational age ranges (123-127 days or 133-135 days). Completeness of the procedure was assessed by demonstrating an attenuated prolactin response to chlorpromazine challenge. Following HPD, gestation was prolonged for at least eight days beyond term (146.2 +/- 1.5 days) in 9 of the 10 fetuses operated. Fetal plasma ACTH1-39 concentrations were not different between the HPD and control fetuses, increasing in all groups with increasing gestation. Fetal plasma cortisol concentrations increased (P < 0.01) in control fetuses over gestation. Cortisol concentrations did not change significantly in the day 125 HPD group following HPD but increased in the day 135 HPD group (P < 0.05) with advancing gestation. These latter concentrations, however were markedly less (P < 0.001) than those for control fetuses prior to parturition. Fetal and maternal plasma PGE2 concentrations increased (P < 0.01) in the control group over gestation but did not change following HPD. Maternal plasma progesterone concentrations decreased (P < 0.05) after day 143 in the control group but did not change in the HPD group.(ABSTRACT TRUNCATED AT 250 WORDS)
Adrenocorticotropic Hormone↗
Thyroid hormone resistance: the role of mutational analysis.
The finding of increased thyroxine (T4) and tri-iodothyronine (T3) levels in a patient with normal or increased thyroid-stimulating hormone is unexpected and presents a differential diagnosis between a thyroid-stimulating hormone-secreting pituitary adenoma, generalized resistance to thyroid hormone (RTH) and laboratory artefact. Without careful clinical and biochemical evaluation, errors may occur in patient diagnosis and treatment. In the case of RTH, mutation of the thyroid hormone receptor beta gene results in generalized tissue resistance to thyroid hormone. As the pituitary gland shares in this tissue resistance, euthyroidism with a normal thyroid-stimulating hormone is usually maintained by increased thyroid hormones. To date, we have identified eight pedigrees in New Zealand with mutations in the thyroid hormone receptor beta gene, including two novel mutations. Mutational analysis of the thyroid hormone receptor beta gene allows definitive diagnosis of RTH, potentially avoiding the need for protracted and expensive pituitary function testing and imaging. Mutational analysis also enables family screening and may help to avoid potential misdiagnosis and inappropriate treatment.
DNA Mutational Analysis↗
The role of sex hormones in problems of the mature years and beyond.
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Aged↗
Canine hypophysectomy using a ventral paramedian approach.
OBJECTIVE: To evaluate the degree of pituitary exposure, completeness of hypophysectomy, and perioperative morbidity associated with an alternative paramedian surgical approach and excisional technique for the canine pituitary gland. STUDY DESIGN: Experimental imaging, surgical, and endocrinologic study. ANIMAL POPULATION: Nine healthy, purpose-bred Beagle dogs. METHODS: Surgical landmarks for the pituitary were determined by computed tomography (CT), and then using a ventral paramedian approach medial to the rami of the mandible, the pituitary was exposed and removed en bloc by manipulation and ultrasonic aspiration. Efficacy of the procedure was evaluated using endocrinologic and pathologic observation. RESULTS: CT images allowed the precise location of surgical landmarks for hypophysectomy. Statistically significant decreases in secretion of all measured pituitary hormones except adrenocorticotropic hormone (ACTH) occurred after hypophysectomy. Despite the absence of gross evidence of residual pituitary tissue, immunohistochemical staining revealed residual pituitary cells in the sella turcica of most dogs. CONCLUSION: CT imaging and a paramedian approach facilitated surgical access to the pituitary gland by a transoral technique; however, use of an ultrasonic aspirator removed all visible pituitary glands but left cellular remnants capable of ACTH secretion in the sella turcica. CLINICAL RELEVANCE: Although this technique did not result in complete hypophysectomy, clinical use in dogs with pituitary-dependent hyperadrenocorticism is warranted because the goal is not complete hypophysectomy but removal of a pituitary tumor.
Adrenocortical Hyperfunction↗
Cumulative hormone release is not area under the time curve.
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Adrenocorticotropic Hormone↗
Long-term immunization against the beta-subunit of ovine luteinizing hormone (oLH beta) has no adverse effects on pituitary function in rhesus monkeys.
One postulated safety hazard of contraceptive methods based on immunization against gonadotropic hormones is the possibility that circulating antibodies which crossreact with pituitary hormones may impair pituitary function through the deposition of immunoglobulin and/or complement suggesting immune complexes. In order to evaluate this possibility in rhesus monkeys actively immunized against the beta-subunit of ovine luteinizing hormone (oLH beta), we used three approaches to study the effects of long-term immunization on pituitary function: a) evaluation of pituitary responsiveness to challenge with a GnRH-agonist; b) examination of pituitary histology and immunostaining with gonadotropin antisera; and c) examination of pituitary cells for deposition of immune complexes. Our results indicate that circulating anti-oLH beta antibodies did not result in significant impairment of pituitary function in rhesus monkeys.
Animals↗