Pretibial myxedema in a euthyroid patient

Pretibial myxedema (PM) is a rare extrathyroidal manifestation of Graves' disease (GD), usually during the hyperthyroid state, coexisting with orbitopathy. We describe a rare case of a biopsy-proven PM in a euthyroid patient, without history of GD or Hashimoto's thyroiditis. Assessment of commonly reported thyroid autoantibodies, such as thyroid peroxidase and thyroglobulin autoantibodies, thyroid stimulating immunoglobulins and thyroid binding inhibitory immunoglobulins, was negative. Resolution of skin pathology was achieved after topical application of corticosteroids and was sustained 1 year later.

Challenges in the Management of a Patient with Myxoedema Coma in Ghana: A Case Report

Myxoedema coma is a rare life-threatening disease, and it is essential that it is managed appropriately to reduce the associated high mortality. However, in the setting where efficient healthcare delivery is hampered by inadequacies, the management of such cases may pose a significant challenge. We present the case of a middle-aged woman diagnosed with myxoedema coma and severe hyponatremia. The case report highlights some of the challenges that may be encountered during the management of myxoedema coma in similar settings and outlines the management strategies undertaken to overcome them in the absence of national guidelines. It also brings to the fore the need for clinicians to look out for clinical features suggestive of hypothyroidism particularly among high risk individuals for early diagnosis and treatment.

FUNDING

None declared.

Heart failure presenting as myxedema coma: case report and review article

Hypothyroidism is a common medical problem easily treated when diagnosed but requiring regular follow-up and patient medication compliance. At times, this diagnosis can go untreated resulting in the development of severe consequences such as Myxedema Coma. Of all the clinical symptoms, cardiovascular manifestations tend to be especially severe and often life threatening.

Preradial myxedema in a euthyroid male: A distinct rarity

Localized or pretibial myxedema is one of the signs of Graves disease (along with goiter, exophthalmus, thyroid acropathy, and high circulating levels of long-acting thyroid-stimulating hormone) and usually tends to occur at a later stage of the disease or even after the patient becomes euthyroid post treatment. Very rarely has it been reported in euthyroid patients. We report a euthyroid man presenting with localized myxedema on the extensor surface of his forearm with clinical and histopathological features consistent with pretibial myxedema. He responded partially to topical clobetasol propionate cream and tacrolimus ointment 0.1 percent for about 7 months. To the best of our knowledge, this is the first case of preradial myxedema in a euthyroid patient in the English international dermatological literature.

Respiratory failure with myxedema ascites in a patient with idiopathic myxedema

Here we report the case of a 50-year-old woman presenting with weight gain, whole-body edema, and massive ascites. Blood examination revealed primary hypothyroidism with TSH-blocking antibody, and the echocardiogram showed diffuse hypokinesis of the left ventricle with pericardial effusion. Although she received thyroid hormone replacement therapy immediately, her ascites increased and she developed type II respiratory failure requiring transient noninvasive positive pressure ventilation (NIPPV). She recovered following the temporary drainage of the ascites, administration of diuretics, and continuous thyroid hormone replacement. The amount of ascites decreased during therapy, along with an increase in thyroid hormone levels. Finally, the ascites disappeared completely, followed by the normalization of the cardiac wall motion. Herein we report this rare case in detail, and also discuss the mechanism by which primary hypothyroidism induced such severe conditions in our patient.

Hla-Dr/Dq Gene Variation in Nongoitrous Autoimmune Thyroiditis at the Serological and Molecular Level

The etiology of autoimmune diseases is multifactorial with genetic factors being an important prerequisite. There are two clinical manifestations of autoimmune thyroiditis: the goitrous form (Hashimoto's thyroiditis) and the atrophic variant, which is characterized by hypothyroidism (primary myxoedema). Different genetic markers were assumed to be predisposing factors for the distinct clinical presentation. In the present study, we determined HLA A,B,C,DR,DQ alloantigens serologically and HLA-DQ by gene analysis in patients with nongoitrous autoimmune thyroiditis and randomly chosen controls. To verify the exact classifications, thyroid volume (median 5.85 ml) was measured by ultrasonography. HLA-DR5 was found in 16 of 36 (44%) patients with nongoitrous autoimmune thyroiditis and in only 26 of 175 controls (15%) (Pc = 0.0018). There was a tendency towards a lower frequency of HLA-DR7 with 6% positivity in patients vs. 29% in controls (Pc = 0.052). Regarding HLA-DQ, DQ7 was found in 17 of 35 patients (48%) vs. 21 of 98 controls (21%) (Pc = 0.028) (relative risk 3.5). No other association was found with HLA-A,B,C and HLA-DR and -DQ. Our data indicate that the genetic susceptibility to autoimmune nongoitrous thyroiditis is closely associated to HLA-DR5 and DQ7 and not distinct from goitrous disease. We conclude that factors other than genetic ones explain the different immunological and clinical manifestation of chronic lymphocytic thyroiditis.

Myxoedema and thyrotoxicosis: relations between clinical state and concentrations of thyroxine and triiodothyronine in blood

The clinical manifestations in thyrotoxic and myxoedematous subjects were assessed by clinical diagnostic score indices and related to the free thyroxine index (FT4I) and the free triiodothyronine index (FT3I), basal metabolic rate (BMR) and in the hypothyroid patients to serum thyrotropin (TSH) level. The clinical score index was significantly correlated to both FT4I and FT3I in both groups of patients. No difference existed in degree of correlation between the clinical score index, on the one hand, and FT3I and FT4I, on the other, in either thyrotoxic or myxoedematous subjects. The degree of correlation between clinical score index and FT3I and FT4I was higher than that between the thyroid hormones and BMR. The clinical score index thus appears to be a better indicator of severity of hyper- and hypothyroidism than BMR. Serum TSH concentration was not correlated to the clinical state.

Myxedema ascites with an extremely elevated CA125 Level: a case report

Carbohydrate antigen 125 (CA125) is a tumor-marker frequently associated with ovarian malignancies; however, benign gynecologic conditions (e.g. ovarian cysts) commonly cause a smaller increase in CA125 levels. This report describes an elderly Japanese woman with high CA125 levels and massive ascites caused by hypothyroidism. A 67-year-old woman presented herself with a weight gain of about 12 kg and abdominal distension. Her serum CA125 level was markedly elevated (822 U/ml) and abdominal CT revealed a right ovarian cyst and massive ascites. Hormonal laboratory data showed severe primary hypothyroidism with a serum TSH of 594 IU/L and a free thyroxin level of 0.05 ng/dl. Ascitic fluid was found to be exudate with a high protein content of 42 g/L. Cytological analysis and FDG-PET showed no evidence of malignancy. The ascites completely disappeared and serum CA125 normalized after adequate hormonal replacement therapy. These data suggest that hypothyroidism should be considered in patients with ascites and elevated serum CA125.

Hypothyroidism and myxedema coma

Hypothyroidism is a common endocrinopathy in dogs but is rare in cats. Lymphocytic thyroiditis and idiopathic thyroid atrophy are common causes of this condition. Specific thyroid function tests, in conjunction with clinical signs and physical examination findings, are used to help confirm a diagnosis of hypothyroidism. This disease can be managed with synthetic hormone supplementation and has an excellent prognosis. Myxedema coma is a rare and potentially fatal manifestation of severe hypothyroidism that can be successfully treated using intravenous levothyroxine.

Myxedema coma

Myxedema coma is the term given to the most severe presentation of profound hypothyroidism and is often fatal in spite of therapy. Decompensation of the hypothyroid patient into a coma may be precipitated by a number of drugs, systemic illnesses (eg, pneumonia), and other causes. It typically presents in older women in the winter months and is associated with signs of hypothyroidism, hypothermia, hyponatremia, hypercarbia, and hypoxemia. Treatment must be initiated promptly in an intensive care unit setting. Although thyroid hormone therapy is critical to survival, it remains uncertain whether it should be administered as thyroxine, triiodothyronine, or both. Adjunctive measures, such as ventilation, warming, fluids, antibiotics, pressors, and corticosteroids, may be essential for survival.

Myxedema coma in a patient with Down's syndrome

INTRODUCTION

hyroid dysfunction is common in Down's syndrome, most common being hypothyroidism. Longstanding, untreated hypothyroidism can lead to myxedema coma.

METHODS

Here we report a patient with Down's syndrome who presented with myxedema coma.

DISCUSSION

The three essential elements for the diagnosis of myxedema coma include altered mental status, defective thermoregulation and a precipitating event or illness; all of these were present in our patient. Also, very high TSH, low T3 and T4, and the rapid response to the treatment with levothyroxine confirmed the diagnosis.

CONCLUSION

Patients with Down's syndrome should have regular screening for thyroid dysfunction.

Myxedema ascites with elevated serum CA 125 concentration

We report a case of myxedema ascites and markedly elevated serum CA 125 concentration. The cause of ascites and elevated tumor markers in hypothyroidism remains unknown. Diagnosis was characterized by no evidence of malignancy seen by transvaginal ultrasonography or abdominal computed tomography and ascites resolution with serum CA 125 normalization after adequate hormonal treatment. Our data suggest that hypothyroidism should be considered in patients with ascites and elevated serum CA 125.

Recombinant monoclonal thyrotropin-stimulation blocking antibody (TSBAb) established from peripheral lymphocytes of a hypothyroid patient with primary myxedema

Anti-TSH receptor antibodies (TRAbs) have been known to be involved in Graves' disease and primary hypothyroidism. We previously isolated and reconstituted immunoglobulin (Ig) genes of Epstein-Barr virus-transformed B cell clones producing monoclonal TRAbs obtained from Graves' patients. In the present study, we performed a similar experiment using a B cell clone, 32A-5, derived from a patient with primary hypothyroidism. The variable region genes of Ig heavy (H) and light (L) chains were isolated and sequenced from the 32A-5 clone. A significant number of somatic mutations were found in variable regions of H and L chain gene segments. Each pair of H and L chain cDNAs was ligated into an expression vector for IgG1 production and stably introduced into myeloma cells. The transfectants were injected ip into BALB/c mice to yield ample volume of the antibody for following applications. Interactions of recombinant 32A-5 with Graves' sera with varying thyroid-stimulating antibody (TSAb) activities were studied. The recombinant antibody tended to suppress TSAb activities in 10 of 15 Graves' sera, in which four were significantly inhibited. In summary, this is the first study to analyze human monoclonal TSH-stimulation blocking antibodies (TSBAb) at the molecular level. Use of human recombinant monoclonal TSBAb may be an analytical tool for molecular-basis etiology and an alternative therapeutic path for Graves' disease.

Myxedema accompanied by huge portal-systemic shunt without portal hypertension

A 43-year-old woman with a huge portal-systemic shunt accompanied by myxedema showed slow speech and behavior. Several imaging studies revealed a bold portal-systemic shunt from the splenic vein to the left renal vein. In addition, hypothyroidism caused by chronic thyroiditis was diagnosed, and synthesized thyroxine replacement was effective for the symptoms. However, the serum ammonia and indocyanin green retention remained in the abnormal range, nevertheless the portal vein pressure was normal and findings of liver cirrohsis were not recognized histologically. Surgical shunt closure was performed, resulting in normalized serum ammonia levels and serum branched chain amino acids /aromatic amino acids ratio, and improvement of the ammonia tolerance test.

[Hyperhomocysteinemia and hypothyroidism]

Moderate hyperhomocysteinaemia is associated with hypothyroidism. Increased levels of homocysteine might contribute to a greater cardiovascular risk. This paper reports a case of transient myxoedema, owing to postpartum thyroiditis. The fluctuation of P-homocysteine was inversely correlated to the free thyroxine index. We recommend TSH screening of patients with unexplained hyperhomocysteinaemia.

Myxedema coma: diagnosis and treatment

Myxedema coma, the extreme manifestation of hypothyroidism, is an uncommon but potentially lethal condition. Patients with hypothyroidism may exhibit a number of physiologic alterations to compensate for the lack of thyroid hormone. If these homeostatic mechanisms are overwhelmed by factors such as infection, the patient may decompensate into myxedema coma. Patients with hypothyroidism typically have a history of fatigue, weight gain, constipation and cold intolerance. Physicians should include hypothyroidism in the differential diagnosis of every patient with hyponatremia. Patients with suspected myxedema coma should be admitted to an intensive care unit for vigorous pulmonary and cardiovascular support. Most authorities recommend treatment with intravenous levothyroxine (T4) as opposed to intravenous liothyronine (T3). Hydrocortisone should be administered until coexisting adrenal insufficiency is ruled out. Family physicians are in an important position to prevent myxedema coma by maintaining a high level of suspicion for hypothyroidism.

Blood volumes and renal function in overt and subclinical primary hypothyroidism

INTRODUCTION

Thyroid dysfunction is associated with marked alterations in cardiovascular and renal functions. In hypothyroidism, myocardial contractility, cardiac output, and oxygen consumption are decreased, whereas peripheral resistance is increased.

METHODS

We assessed blood volumes and effective renal plasma blood flow (ERPF) and glomerular filtration rate (GFR) in 17 patients with overt primary hypothyroidism and in 15 of these patients when in euthyroid state after substitutive therapy. We performed the same measurements in eight patients with subclinical hypothyroidism.

RESULTS

In the hypothyroid state, the plasma volume measured by dilution of 125I-albumin (APV) was higher than the calculated plasma volume (CPV) from packed red cell mass, suggesting an extravascular escape of albumin. After substitutive therapy, the CPV showed a statistical increase (P < 0.05), whereas APV remained unchanged. Both ERPF and GFR increased after thyroxine therapy (p < 0.05). In the subclinical group, blood volumes and renal function were similar to those found in the other group of patients when in the euthyroid state.

CONCLUSIONS

We conclude that in primary hypothyroidism, ERPF and GFR are low, but that these values improve with substitutive therapy. CPV is a better index of the current plasma volume than APV. The difference between these two parameters suggests that the escape of albumin into the extravascular space in primary hypothyroidism is terminated by treatment. There are no clear abnormalities either in blood volumes or in renal function in subclinical hypothyroidism.

Scleromyxedema: a complete response to prednisone

Scleromyxedema is a disorder characterized by a typical rash due to the accumulation of mucin in the dermis. It is always associated with a monoclonal protein in the serum and can have a wide variety of systemic manifestations. We describe a 40-year-old woman who had scleromyxedema associated with a monoclonal G lambda protein. Severe systemic symptoms included fatigue, esophageal dysmotility, and myopathy. Symptoms resolved completely with oral prednisone therapy, and she remained in clinical remission 24 months after use of prednisone was discontinued. Scleromyxedema is commonly treated with alkylating agents, which have been associated with pronounced morbidity and mortality. We suggest that oral corticosteroid therapy may be a reasonable initial choice for treating this disease and that alkylating agents be reserved for corticosteroid-refractory disease.

Hypoplastic anaemia complicating myxoedema coma

The case of a 68 year old women presenting in myxoedema coma is described. She was found to be anaemic with a haemoglobin of 8.2 g/dl. Further investigations showed a pancytopenia and a hypoplastic anaemia confirmed by bone marrow. The patient recovered and became euthyroid following initial treatment with intravenous tri-iodothyronine (T3) and later oral thyroxine (T4) replacement with resolution of pancytopenia and return of bone marrow to normal.

Analysis of antibody-dependent cell-mediated cytotoxicity in autoimmune thyroid disease

There is no consensus on the role of antibody-dependent cell-mediated cytotoxicity (ADCC) in autoimmune thyroid disease; recent reports have suggested that antibodies mediating ADCC are found particularly in patients with primary myxoedema, occur less frequently in Hashimoto's thyroiditis and are absent in Graves' disease. Using an ADCC assay with a single source of effector and target cells, and expressing results as lytic units, we have found antibodies capable of mediating ADCC in 9 of 17 patients with primary myxoedema, 9 of 22 patients with Hashimoto's thyroiditis and 6 of 22 patients with Graves' disease. There was no significant difference between the groups in this distribution. Mean levels of ADCC activity were not significantly different comparing primary myxoedema and Hashimoto's thyroiditis patients, although levels were lower in Graves' disease patients compared to those with Hashimoto's thyroiditis (P < 0.05). There was no correlation between TPO antibodies (total IgG or IgG subclasses) measured by ELISA and ADCC activity. These results suggest that thyroid antigens besides TPO are involved in ADCC and that antibodies mediating ADCC are not restricted to subgroups of patients with autoimmune thyroid disease.

Increased serum creatinine associated with severe primary hypothyroidism

A case of myxoedema due to Hashimoto's thyroiditis associated with a significant increase in serum creatinine is reported. Thyroid hormone replacement therapy resulted in normalization of the serum biochemistry within 1 month.

Localized myxedema, associated with increased serum hyaluronic acid, and response to steroid pulse therapy

A 66-year-old man presented with Graves' disease and widespread localized myxedema. Extensive lesions were present on the legs, feet, hands, and face. TSH receptor antibody (TBII) was markedly positive and the serum hyaluronic acid level was very high. Intravenous steroid pulse therapy was followed by oral therapy with gradual tapering. This regimen markedly improved the skin lesions and resulted in a decrease of the serum hyaluronic acid level. The findings suggest that steroid pulse therapy is effective for the treatment of extensive localized myxedema. In addition, the serum hyaluronic acid level may be a useful parameter for the follow-up of patients with this condition.

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.

Assessment of bone remodeling using biochemical indicators of type I collagen synthesis and degradation: relation to calcium kinetics

In this study, we investigated the relation between calcium kinetic indices of bone remodeling (resorption rate, r; and formation rate, m, respectively) and two serum markers of type I collagen turnover: the pyridinoline cross-linked carboxyterminal telopeptide domains of type I collagen (S-ICTP a marker of bone matrix degradation) and the carboxyterminal propeptide of human type I procollagen (S-PICP, a marker of bone matrix formation). We studied three groups: (i) healthy controls (n = 19), (ii) a mixed group of high and low-turnover bone diseases without mineralization defects (myxedema, thyrotoxicosis and primary hyperparathyroidism n = 38), and (iii) osteoporosis (n = 52). In healthy controls, a significant regression of S-PICP on m was obtained (R = 0.53, SEE/Y = 0.44, P < 0.02). Significant regressions were also demonstrable in high- and low-turnover bone disease (R = 0.50, P < 0.001), SEE/Y = 61%) and osteoporosis (R = 0.49, P < 0.001, SEE/Y = 50%). In controls the regression coefficient for the regression of S-ICTP on r was 0.19 (NS), in high and low turnover bone disease 0.66, (SEE/Y = 59%, P < 0.001) and in the osteoporotic group 0.40 (SEE/Y = 61%, P < 0.01). We conclude that S-PICP and S-ICTP reflect whole skeletal bone formation and resorption rates in a variety of metabolic bone diseases including osteoporosis.

Serum markers of type I collagen formation and degradation in metabolic bone disease: correlation with bone histomorphometry

Type I collagen makes up more than 90% of bone matrix. Therefore, analysis of antigens related to collagen formation and degradation in bone should provide good and specific estimates of both bone resorption and bone formation rates. In this study we measured serum levels of the pyridinoline cross-linked telopeptide domain of type I collagen (ICTP) as a marker of bone resorption and serum carboxy-terminal propeptide of type I procollagen (PICP) as a marker of bone formation. Serum levels of the two antigens were correlated to histomorphometric indices of bone resorption and bone formation calculated from iliac crest bone biopsies in a group of 18 individuals with high- and low-turnover bone disease (myxedema, primary hyperparathyroidism, and thyrotoxicosis). After logarithmic transformation the regression of S-ICTP on volume-referent resorption rate (BRs/R/BV) was significant (r = 0.61, p < 0.01, SEM/Y = 56%). S-ICTP also showed a significant regression on the volume-referent cancellous bone balance (r = -0.45, p < 0.05, SEM/Y = 412%). S-PICP was significantly correlated to the mineral appositional rate (r = 0.53, p < 0.05) and volume-referent bone formation rate (r = 0.61, p < 0.01, SEM/Y = 48%). The correlation to bone turnover as expressed in the activation frequency was also highly significant (r = 0.61, p < 0.01, SEM/Y = 51%). No significant correlation with wall thickness or bone balance was demonstrable per remodeling cycle. Thus, assays employing antigens that reflect collagen formation and degradation are useful instruments for the evaluation of rates of bone remodeling in metabolic bone disease.

Respiratory muscle strength in hypothyroidism

To investigate respiratory muscle strength in patients with hypothyroidism, global respiratory muscle strength was assessed by measuring mouth pressure during PImax and PEmax efforts. Maximum pressures, VC, FEV1, FVC, T3, T4, and TSH were measured in 43 hypothyroid patients. Measurements were made before and three months after replacement therapy with thyroxine. The results showed that the mean value of PImax and PEmax increased after treatment. Significant change was found in the mean value of VC, FEV1, and FVC after treatment but not in the FEV1/FVC ratio. A highly statistically significant linear relationship was found between PImax and TSH and between PEmax and TSH as well as between PImax and T3 and PEmax and T3. We conclude that hypothyroidism affects respiratory muscle strength and that this weakness is linearly related to thyroid hormone levels. Respiratory muscle weakness is present in both inspiratory and expiratory muscles and is reversible with treatment.

Thyroperoxidase, but not the thyrotropin receptor, contains sequential epitopes recognized by autoantibodies in recombinant peptides expressed in the pUEX vector

The sequential epitopes on the human thyroperoxidase (TPO) recognized by antibodies in the sera of patients with autoimmune thyroid disease were investigated using a recombinant DNA technique. Previous studies led to the isolation of two overlapping cDNA clones that encode polypeptides of TPO (85 residues, C2; 100 residues, C21) recognized by sera from several patients with autoimmune disease that contained antimicrosomal autoantibodies. In this report the vector pUEX1 was used to clone and express small random fragments of TPO cDNA in Escherichia coli as a beta-galactosidase fusion protein. Colonies were screened with a serum from a patient with Hashimoto's thyroiditis, and immunoreactive peptides were identified by sequencing the corresponding DNA inserts. Two linear epitopes of human TPO (amino acids 590-622 and 710-722) were recognized by the autoantibodies. This confirmed our previous results and provide a more precise localization of the antigenic determinants involved. The same approach has been applied in an attempt to identify the binding site(s) for autoantibodies on the human TSH receptor. In contrast to the data obtained with TPO, sera from patients with blocking (from idiopathic myxoedema) or stimulating (from Graves' disease) activity did not recognize the linear TSH receptor peptide fragments generated in our libraries.

Myxedema ascites. Report of two cases and review of the literature

Ascites is a well-known but uncommon occurrence in hypothyroid patients. We describe two patients with clinical ascites that resolved completely on thyroid replacement therapy. Our review of the literature found 21 well-documented cases of myxedema ascites. Prominent features of this condition include a high protein content of the ascitic fluid (greater than 2.5 g/dl), a high albumin serum-ascites gradient, a long duration of the ascites, and its resolution on thyroid replacement. We also found a slight female predominance. The exact mechanisms responsible for ascites accumulation are unknown and some of the hypotheses are discussed. We conclude that ascites associated with hypothyroidism is rare but must be recognized early since thyroid replacement is definitive therapy.

Myxedema mimicking myocardial ischemia in a young black male

High elevations of creatine kinase secondary to myxedema in a 29-year-old black male resulted in an erroneous diagnosis of mycardial infarction.

Myxoedema coma: response of thyroid hormones with oral and intravenous high-dose L-thyroxine treatment

Myxoedema coma is a medical emergency with high mortality. In this study, clinical response and plasma variations of thyroid hormones were analysed in 7 patients, 6 presenting with myxoedema coma and one with myxoedema ileus. These patients were treated with intravenous or oral l-thyroxine (l-T4). 1000 mu l-T4 iv were administered in two patients. Within 3 h, plasma T4 and triiodothyronine (T3) reached a peak upper normal range, then diminished slowly during 5-9 days. The 5 remaining patients were treated with 500 micrograms l-T4 po on the first day, then 100 micrograms l-T4 daily by mouth. Plasma T4 and T3 increased slowly, remaining in hypothyroid range but clinical response (assessed on mental status, pulse rate and body temperature) occurred within 24-72 h. Cortisone therapy was used in 3 patients. Two patients died of myocardial infarction, or septicemia, one while receiving cortisone therapy and i.v. l-T4, another one treated only by oral l-T4. This study suggests: 1) oral absorption of l-T4 is variable, but clinical response occurs quickly even in myxoedema ileus; 2) the intravenous route involves high peaks of plasma T4 and T3; 3) peripheral conversion of T4 to T3 allows gradually T3 delivery to organ systems, even if only l-T4 is used and 4) initial and daily dosage determinations need further studies.

[Study on the metabolic changes of hormones regulating water and electrolytes before and after acute water loading in myxedematous patients]

The average plasma AVP in 12 cases of patients with overt myxedema was higher than that of normal controls (n = 5) before water loading, though there was no significant difference (P greater than 0.05). The plasma ANP levels were increased (P less than 0.05). After water loading the average plasma osmolality level of patients was lower, and the mean plasma AVP concentration of patients was not suppressed after loading. A disturbance in water clearance was demonstrated. The mean levels of plasma ANP and aldosterone were not markedly changed in patients before and after loading. These observations coincide with the changes of SIADH. Most of the above blood parameters were improved along with thyroid function in 9 patients who were restored to normal after replacement with desiccated thyroid.

Osmoregulation of plasma vasopressin in myxedema

We studied osmoregulation of plasma vasopressin (AVP) in eight patients with untreated myxedema due to primary hypothyroidism. All patients had severe thyroid hormone deficiency due to chronic thyroiditis and had been receiving no medication at the time of this study. AVP release was defined by 5% hypertonic saline infusion test in all patients, and urinary diluting capacity was estimated by the iv water-loading tests in five patients. Plasma AVP was measured by sensitive and specific RIA. The mean basal plasma AVP level in the patients (0.5 +/- 0.1 pmol/L) was significantly lower (P less than 0.01) than that in normal adults (2.5 +/- 0.5 pmol/L). During hypertonic saline infusion, the rise in plasma AVP was normal or subnormal in all patients. In two patients who showed mild to moderate hyponatremia in the basal state and mild urinary diluting defect during water loading, plasma AVP was appropriately suppressed in each case. These results indicate that inappropriate elevation of plasma AVP is not common in myxedema, and that impaired water excretion is due mainly to AVP-independent mechanisms.

Endemic cretinism: possible role for thyroid autoimmunity

Thyroid atrophy, rather than goitre, is a characteristic feature of myxoedematous cretinism but its cause and nature are unknown. In this study, purified IgG fractions of serum from patients with myxoedematous endemic cretinism inhibited thyrotropin-induced DNA synthesis in guineapig thyroid segments in a sensitive cytochemical bioassay. IgG from patients with euthyroid neurological endemic cretinism or from normal subjects did not inhibit thyroid growth. Furthermore, in myxoedematous subjects, the presence of the thyroid-growth-blocking immunoglobulins showed a positive relation with thyroid atrophy found on ultrasound. These findings provide a pathogenic basis for the variable clinical expression of endemic cretinism.

Selenium deficiency as a possible factor in the pathogenesis of myxoedematous endemic cretinism

Myxoedematous endemic cretinism is prevalent in African goitre endemies. It has been related to a thyroid 'exhaustion' atrophy occurring near birth. It is proposed that this might result from the low resistance of a fragile tissue to enhanced H2O2 generation under intense thyroid stimulation by thyrotropin. In support of this hypothesis, low selenium and glutathione peroxidase serum levels have been found in the African endemic area of the Idjwi Island (Kivu, Zaire). Serum selenium and plasma glutathione peroxidase were lower in the area of high endemicity of goitre and cretinism (Northern part of the Island). However, only the former difference is statistically significant. These data thus suggest a role of oligoelements and oxygen toxicity in the pathogenesis of endemic cretinism.

Marrow myxedema. Gelatinous transformation of marrow ground substance in a patient with severe hypothyroidism

Replacement of marrow ground substance by hyaluronic acid-rich mucopolysaccharides (gelatinous transformation) has been previously reported to occur in severely malnourished patients. A patient with severe anemia and hypothyroidism without malnutrition was found to have gelatinous transformation of the marrow. This process is similar histologically to dermal myxedema, and the findings in this patient suggest questions for further study involving possible roles for thyroid-stimulating hormone in the development of marrow and visceral myxedema and the alterations in the normal partitioning process between serum and red blood cell low-density lipoproteins that produce acanthocytes in blood smears from patients with hypothyroidism.

Ultrafiltration method for direct radioimmunoassay measurement of free thyroxine and free tri-iodothyronine in serum

Ultrafiltration at physiological pH and temperature of undiluted serum followed by direct radioimmunological determination of T3 and T4 in the protein-free ultrafiltrate offers the best possible approach towards estimation of in vitro plasma levels of free T3 and free T4. The major technical difficulties in meeting this apparently simple proposition are: establishing adequately sensitive radioimmunoassays; avoidance of adhesion to ultrafilters and glassware; removal from the ultrafilters of compounds which would cross-react or interfere in the radioimmunoassays; and avoidance of co-filtration of thyroid hormone binding proteins in serum, which would obviously imply spurious data. This methodological study describes the magnitude and significance of each of these obstacles and how to circumvent them. Practically all other available methods, including equilibrium dialysis, imply dilution of serum samples with buffer often leading to alterations in ionic composition to which thyroid hormone binding to proteins is peculiarly sensitive. Dilution itself alters the fraction of free thyroid hormones in serum especially when pharmaca or compounds are present which compete for the binding sites. These pitfalls are avoided in ultrafiltration of undiluted serum. This is illustrated through measurements on serum containing therapeutic concentrations of Fenclofenac which was found to displace 120% more T4 in undiluted than in diluted (1:28) serum. Using the described technique FT3 was 8.8 +/- 1.7 pmol/l and FT4 30.8 +/- 8.2 (SD) pmol/l in serum from 29 normal subjects. Pregnant women in their third trimester had lower levels: FT3 7.1 +/- 2.1 and FT4 17.6 +/- 5.8 pmol/l (SD, n = 24).

Plasma somatostatin is elevated in primary hypothyroidism compared with hyperthyroidism

Increased pancreatic somatostatin (somatotrophin release inhibiting factor (SRIF) has been found in hypothyroid rats. Therefore, we wanted to investigate plasma SRIF in patients with hypo- and hyperthyroidism. Two groups of patients, 7 cases with autoimmune hypothyroidism, 31-75 years old, and 7 cases with Graves' disease, 19-43 years old, were compared with regard to plasma SRIF before, during and after an arginine infusion (0.5 g/kg/20 min). None of the patients suffered from diabetes mellitus or obesity. Plasma SRIF was higher in the hypothyroid patients (mean basal value 21.5 +/- 3.9, peak value 28.7 +/- 5.1 pmol/l) compared with the hyperthyroid group (mean basal value 11.6 +/- 3.3, peak value 16.2 +/- 4.0 pmol/l). The hypothyroid group also had significantly higher serum insulin values during arginine stimulation. No difference was found in plasma glucagon, serum growth hormone (GH) or blood glucose. In conclusion, plasma SRIF is elevated in primary hypothyroidism compared with hyperthyroidism. The reason for this finding is uncertain, but a reduced SRIF clearance is a possible explanation. The association of our findings with the reduced glucose tolerance in hyperthyroidism is discussed.