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At least 19 recordsLinked to original sources
PubMed1978

Diagnosing and treating myxedema and myxedema coma.

Every patient with myxedema has hypothyroidism, but not every hypothyroid patient has myxedema. It often is possible to diagnose myxedema on clinical grounds alone. Characteristic symptoms are weakness, cold intolerance, mental and physical slowness, dry skin, typical facies, and hoarse voice. Results of the total serum thyroxine and free thyroxine index tests usually will confirm the diagnosis. L-thyroxine is the treatment of choice for myxedema, but it must be given to elderly patients with extreme caution. The transition from the hypothyroid to the euthyroid state brings about changes that put an added burden on the heart. The patient's clinical status and results of thyroid function tests determine the proper maintenance dose. Myxedema coma is rare but often fatal. It occurs most often in elderly women and may be mistaken for one of the chronic debilitating diseases common to this age group. Primary treatment is prompt administration of adequate doses of thyroid hormone--either l-throxine given intravenously of L-triiodothyronine given by nasogastric tube. It also is essential to identify and treat the condition precipitating the coma.

Coma↗
PubMed1985

Altered skin elastic fibers in hypothyroid myxedema and pretibial myxedema.

Elastic fibers account for 2% of dermal volume and are responsible for normal skin resiliency. We investigated a disorder of the dermal elastic component as the mechanism for the decreased elasticity of skin in myxedema. Skin biopsy specimens were obtained from patients with thyroid diseases and normal subjects matched for age, sex, and biopsy location. Elastic fiber concentration, determined by computerized morphometric analysis of Verhoeff-van Gieson-stained sections, was significantly lower than normal in hypothyroid and pretibial myxedema. The decreased elastin concentration was not a consequence of the glycosaminoglycan infiltration. Ultrastructural studies of myxedematous skin showed wide variability of elastic fiber diameter and decreased microfibrils. Myxedema (hypothyroid and pretibial) is consistently associated with quantitative and qualitative defects of dermal elastic fibers.

Adult↗
PubMed1994

TSH and TSH receptor antibody-binding sites in fibroblasts of pretibial myxedema are related to the extracellular domain of entire TSH receptor.

The role of TSH receptor antibodies in the pathogenesis of pretibial myxedema is still unclear. This study was designed to determine whether patients with pretibial myxedema had higher serum titers of TSH receptor antibodies, and whether there were TSH and TSH receptor antibody-binding sites on plasma membranes of fibroblasts derived from the skin of pretibial myxedema. If there were, were the binding sites similar to the TSH receptor? The TSH receptor antibodies were determined with radioreceptor assay in 20 normal subjects, 18 hyperthyroid Graves' disease patients without ophthalmopathy, 26 hyperthyroid Graves' disease patients with ophthalmopathy, and 11 patients with pretibial myxedema associated with Graves' ophthalmopathy. TSH and TSH receptor antibody-binding sites were studied on plasma membranes of fibroblasts cultured from the skin of pretibial myxedema with radioreceptor assay. RNA was also extracted from the fibroblasts of pretibial myxedema and reverse transcribed using random primers as the primers for cDNA synthesis. The resulting cDNAs were subjected to amplification by polymerase chain reaction with the use of a set of primers spanning the 5' region (+256/+275 and +616/+635) and the 3' region (+1819/+1838 and +2405/+2424) of the TSH receptor cDNA (+1 transcription start codon). They were further identified by Southern blot hybridization, with the probe spanning the 5' region (+272/+612) and the 3' region (+1908/+2268) of the TSH receptor cDNA (+ 1 transcription start codon), and sequencing. The results showed that patients with pretibial myxedema had higher titers of TSH receptor antibodies in the serum. TSH and TSH receptor antibody-binding sites were present on plasma membranes of fibroblasts derived from the skin of pretibial myxedema patients and related to the extracellular domain of the TSH receptor. These data suggest a common antigenic site in the skin and in the thyroid as a putative target for TSH receptor antibodies or lymphocytes of Graves' disease.

Adult↗
PubMed1993

Orbital decompression in Graves' ophthalmopathy associated with pretibial myxedema.

Pretibial myxedema (thyroid dermopathy), an uncommon autoimmune manifestation of Graves' disease, is almost always associated with significant ophthalmopathy and may be a marker for an unusually prolonged or different course for the ophthalmopathy. However, it is not known if the response to therapy for eye disease is different in patients with pretibial myxedema. We compared the results of orbital decompression in 385 patients without and 52 patients with pretibial myxedema operated on between 1969 and 1989. Preoperative and postoperative characteristics of severe Graves' ophthalmopathy did not differ in patients with or without pretibial myxedema except for slightly, but not significantly, more proptosis and diplopia in the pretibial myxedema group. In response to a 1989-1990 questionnaire (83% response rate, n = 364), 89.1% without (n = 319) and 88.9% with (n = 45) pretibial myxedema reported satisfactory or acceptable appearance of the eyes. Self-assessment of visual acuity, eye comfort, diplopia, and overall rate of satisfaction with the status of the eyes did not differ between the groups. The presence of pretibial myxedema does not herald an unsatisfactory response to transantral orbital decompression.

Adolescent↗
PubMed1989

Value of clinical features for distinguishing myxedema ascites from other forms of ascites.

The diagnosis of myxedema ascites is often difficult and delayed, from our experience and the reports of other investigators. To address this situation, previous reports on the diagnosis of ascites were pooled in order to distinguish the features of myxedema ascites from other forms of ascites. These features were confined to variables that would be obtained routinely from patients with ascites requiring paracentesis. The data of 26 patients with myxedema ascites, and 61 patients with ascites from another cause were analyzed. Discriminant analysis was used to select the variables that best separated patients into myxedema and non-myxedema groups. The variables selected were if the ascites was straw-colored or with a protein content less than 2.5 g/dl, if the patient was over age 40, and if there was periorbital edema or hepatomegaly. These variables correctly classified 90.8% of patients. However, considering the roughly 1% prevalence of myxedema ascites among patients with ascites, the predictive value of these variables, in combination, is only 8.7%. With this low rate, these variables should probably not be used to screen for myxedema ascites.

Adult↗
PubMed1993

[Myxedema coma as a rare postoperative complication].

Myxedema coma is characterized by severe lack of thyroid hormones, unconsciousness and serious restriction of vital functions. The mortality rate still ranges between 50 and 80%. In patients with inapparent hypothyroidism myxedema coma occasionally follows surgery, anesthesia or severe infection. A case of myxedema coma following surgery is reported. CASE REPORT. A 46-year-old woman was anesthesized for hip replacement. The intraoperative cardiovascular situation was characterized by hypotension and tachycardia. On the first postoperative day, unexpectedly a cardiac arrest occurred. Resuscitation with high doses of epinephrine was successful. There was no evidence of myocardial infarction, hypoxia and pulmonary embolism as causative factors for cardiac arrest. A pulmonary artery catheter was inserted and showed low cardiac output. Catecholamines and intravascular fluids were administered without hemodynamic improvement. In the next 5 days pneumonia was followed by ARDS and acute renal failure. After successful treatment of these complications the patient remained in deep coma. An intracerebral disease could be excluded by computerized tomography. Evaluation showed low thyroid hormones (T3; T4) and elevated TSH. The diagnosis of a myxedema coma was assumed. After failure of oral therapy with L-thyroxine (0.025-0.05 mg/day) for 10 days, intravenous therapy with 0.5 mg L-thyroxine was performed. Thirty-six hours later the patient regained consciousness, without cardiac complications. The patient progressed uneventfully under oral therapy with 0.1 mg L-thyroxine and was discharged from the hospital 6 weeks later. DISCUSSION. Pathophysiology and symptomatology of a case of postoperative myxedema coma are described (Tables 1-4). In this patient, the following symptoms occurred: low thyroid hormones (T3; T4), elevated TSH, deep coma, decreased ventilatory response to CO2, diminished myocardial contractility under catecholamine stimulation, impaired renal water excretion. After failure of oral substitution of L-thyroxine, intravenous therapy had to be performed in spite of the high risk of further cardiac complications in this patient. This led to complete recovery with normal neuropsychological and cardiopulmonary parameters. CONCLUSION. Myxedema coma is a rare complication in postoperative care, but in cases of inexplicable unconsciousness thyroid failure should be excluded. If myxedema coma is evident, intravenous therapy with L-thyroxine should be performed under the conditions of extended monitoring.

Coma↗
PubMed1975

Ventilatory control in myxedema and hypothyroidism.

Alveolar hypoventilation is known to occur in myxedema. To clarify the role of hypoxic ventilatory drive and hypercapnic ventilatory drive in thyroid hormone insufficiency states, 10 patients with myxedema and seven with hypothyroidism (thyroid ablation) were studied before and after thyroid replacement. An index developed for hypoxic ventilatory drive was markedly reduced in myxedema: 17 plus or minus 4.7 (S.E.M.) (normal, 126 plus or minus 8.7) (P smaller than 0.01) and increased to 78 plus or minus 12.6 (p = 0.02) with thyroid hormone replacement. In the hypothyroid group this index was also depressed as compared to normal at 67 plus or minus 20 (p smaller than 0.01) and increased to 114 plus or minus 19 (p smaller than 0.02) with replacement. An index for hypercapnic ventilatory drive was depressed in myxedema, 0.69 plus or minus 0.01), but was not significantly depressed in hypothyroidism. With thyroid hormone replacement this index did not significantly increase in either group. We conclude that both myxedema and hypothyroid states produce depression of hypoxic ventilatory drive that is responsive to replacement therapy. This alteration in ventilatory control may contribute to the hypoventilation seen in myxedema.

Adult↗
PubMed1987

Inhibition of thyrotropin-induced growth of rat thyroid cells, FRTL-5, by immunoglobulin G from patients with primary myxedema.

We studied thyroid growth-blocking activity in immunoglobulin G (IgG) fractions of serum from 24 patients with primary myxedema, 24 patients with goitrous Hashimoto's thyroiditis, and 18 normal subjects by measuring the ability of their IgG to inhibit TSH-induced [3H]thymidine incorporation into DNA in a rat thyroid cell line, FRTL-5. Both groups of patients were receiving T4 when studied. [3H]Thymidine incorporation induced by 0.1 mU/ml bovine TSH was significantly inhibited by the addition of 2 mg/ml IgG from patients with primary myxedema (P less than 0.01), while it was not affected by IgG from the normal subjects or 23 of the 24 patients with goitrous Hashimoto's thyroiditis. IgG from patients with primary myxedema also inhibited the [3H]thymidine incorporation induced by Graves' IgG, but not that induced by forskolin, cholera toxin, (Bu)2cAMP or phorbol-12-myristate-13-acetate. The inhibition of TSH-induced [3H]thymidine incorporation by IgGs from patients with primary myxedema was significantly correlated with their inhibitory activities against both TSH-induced cAMP generation and TSH binding (P less than 0.001). These data indicate that these growth-blocking antibodies are directed against the TSH receptor and might be one of the causes of the thyroid atrophy in patients with primary myxedema.

Adolescent↗
PubMed1989

Inhibition of thyrotropin-stimulated adenylate cyclase activation and growth of rat thyroid cells, FRTL-5, by immunoglobulin G from patients with primary myxedema: comparison with activities of thyrotropin-binding inhibitor immunoglobulins.

We studied the blocking type TSH receptor antibodies in 28 patients with primary myxedema and 21 patients with goitrous Hashimoto's thyroiditis by measuring the ability of their IgGs to inhibit TSH binding to its receptor, and to inhibit TSH-stimulated cAMP increase and [3H]thymidine incorporation in a rat thyroid cell line, FRTL-5. The incidences of TSH binding inhibitor immunoglobulin, thyroid stimulation inhibiting immunoglobulin and thyroid growth inhibiting immunoglobulin in patients with primary myxedema were 54.6, 75 and 65.2%, respectively, against 14.3, 0 and 17.7%, respectively, in goitrous Hashimoto's thyroiditis. The antibodies inhibited dose-dependently not only TSH stimulated but also Graves' IgG-stimulated cAMP increase and [3H]thymidine incorporation. The TSH binding inhibitor immunoglobulin activities in patients with primary myxedema were significantly correlated with both the thyroid stimulation inhibiting immunoglobulin (r = 0.665; P less than 0.01) and the thyroid growth inhibiting immunoglobulin (r = 0.618; P less than 0.01) activity. Thirteen patients whose TSH binding inhibitor immunoglobulin activities were more than 50% had both strong thyroid stimulation inhibiting immunoglobulin (75.1-100%) and thyroid growth inhibiting immunoglobulin (57.4-100%) activities. These data suggest that the vast majority of patients with primary myxedema have potent blocking type TSH receptor antibodies. These might play a role in primary myxedema causing hypothyroidism and thyroid atrophy through inhibiting TSH-stimulated cAMP generation.

Adenylyl Cyclases↗