Biomedical subjects
Publications and source records attributed to J P Lock.
We treated a case of iatrogenic hypermagnesemia that clinically mimicked a central brain-stem herniation syndrome. Hypermagnesemia (magnesium level, 9.85 mmol/L [24 mg/dL]) can cause parasympathetic blockade, inducing fixed and dilated pupils, in addition to neuromuscular blockade. Extreme hypermagnesemia can therefore mimic a midbrain syndrome and cause a pseudocomatose state.
Three female siblings with isolated gonadotropin deficiency were studied. None demonstrated hyposmia or craniofacial abnormalities. Single doses of luteinizing hormone-releasing hormone and thyrotropin-releasing hormone (TRH) produced markedly different responses within the kindred. Following administration of TRH, one subject displayed a sharp rise in prolactin, but thyrotropin did not change.
Plasma concentrations of vasopressin and plasma renin activity were measured every 30 min for 24 h in 5 normal active humans, in 1 normal woman confined to bed (except for brief periods up to the bathroom), in 2 active patients with primary aldosteronism and in 1 patient with low-renin hypertension. Plasma vasopressin varied markedly over the day and night in a pattern suggesting episodic secretion of the hormone in the normal subjects. Assumption of upright posture was accompanied by a rise in plasma levels from undetectable to 20--50 pg/ml. Episodic secretion, however, also occurred during bed rest and sleep. In contrast, patients with primary aldosteronism and low-renin hypertension had plasma vasopressin levels considerably lower than the normals, and their profiles of plasma concentration lacked the peaks seen in normals. In the normals, although vasopressin and renin secretion often coincided, only 2 of 6 studies showed a significant correlation between the plasma levels of the two hormones. This study, therefore, shows that vasopressin is secreted periodically in normal humans, that upright posture is an important modulator of secretory activity and that the renin-angiotensin system may or may not influence the pattern of secretion. In addition, it underlines the necessity of recumbency in establishing the existence of a circadian rhythm of plasma vasopressin levels.
A 25-year-old woman was seen for the complaint of secondary amenorrhea. Skull roentgenograms revealed a markedly enlarged sella turcica. Studies of pituitary and hypothalamic function including prolactin were normal. A pneumoencephalogram revealed dilated ventricles and a mass in the septum pellucidum and hypothalamus. Partial removal of this hypothalamic astrocytoma and placement of an interventricular shunt resulted in the return of menses. Recurrent obstruction a few months later resulted in headache, disorientation, and amenorrhea. A shunt was placed again, resulting in clearing of symptoms and a reestablishment of normal menstrual cyclicity. It appears that the occurrence of increased intracranial pressure rather than the hypothalamic tumor caused the amenorrhea.
An 18-year-old patient with Turner's syndrome presented with cyclical vaginal bleeding and spontaneous development of secondary sexual characteristics. She demonstrated classic features of Turner's phenotype, and a culture of blood lymphocytes revealed a 45,XO karyotype. The patient's plasma and urinary estrogen concentrations were similar to those in normal adult women in the late proliferative phase. In contrast, luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels were elevated to values seen in postmenopausal women. Dynamic testing revealed no estrogen response to human menopausal gonadotropin (/MG) and a paradoxical fall in estrogen after administration of human chorionic gonadotropin (hCG). Administration of luteinizing hormone-releasing hormone (LH-RH) resulted in an exaggerated response of both gonadotropins. Dilatation and curettage revealed endometrial hyperplasia, and a laparotomy revealed the presence of 2 gonadlike structures. The histologic diagnosis was lutein cyst. Karyotyping of lymphocytes, skin from the abdominal incision, and tissue from both gonadal structures revealed a 45,XO karyotype without evidence of mosaicism.
A patient with primary hyperparathyroidism underwent cervical exploration and hemithyroidectomy. Only one normal parthyroid gland was found and was removed. Hypercalcemia persisted and subsequent arteriography localized a large mediastinal adenoma which was excised. Parathyroid autotransplantation of a small part of this tissue was performed and the patient was well for over a year. He again became markedly hypercalcemic and graft-dependent elevation of parathromone levels was demonstrated. Autograft resection resulted in normocalcemia. Nineteen months later hypercalcemia and elevated parathormone levels prompted re-exploration of the graft site and another enlarged implant was removed. This restored normocalcemia and normal parathromone levels. Parathyroid adenomatous tissue has the potential for autonomous hyperfunction, and caution must be exercised in its use in autotransplantation.
We describe 3 patients with metastatic medullary carcinoma of the thyroid who were treated with doxorubicin hydrochloride (Adriamycin). Serum calcitonin was measured before and after doxorubicin therapy. Doxorubicin failed to arrest the progression of the disease in any of the patients. Although serum calcitonin levels dropped in 1 patient during therapy, they remained markedly elevated in all 3 patients. From the present series it appears that medullary thyroid carcinoma often does not have a response to doxorubicin.
A case of a 21-year-old woman with Cushing's disease due to a pituitary tumor is described. The patient was treated with cyprohepatadine for 4 weeks immediately following pituitary alpha-particle irradiation. A standard vasopressin test to measure ACTH-mediated cortisol release was performed four times: prior to pituitary irradiation, after irradiation, after 4 weeks of cyproheptadine therapy, and off cyproheptadine for 2 weeks. Cyproheptadine failed to modify vasopressin-stimulated cortisol release in the patient described. This study suggests that cyproheptadine, which has previously been shown to decrease ACTH secretion, probably acts principally at the hypothalamic, rather than at the pituitary level.
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