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.