Hyponatraemia complicating the treatment of myxoedema coma. A case report

Hyponatraemia is a common complication of severe hypothyroidism, but is usually readily corrected by administering L-thyroxine. A case of myxoedema coma in which the serum sodium level dropped precipitously when therapy was started is described and it is suggested that this was due to a state of relative hypocortisolism. Serum sodium values should be closely monitored in myxoedema treated with L-thyroxine; their decrease may signal the onset of an Addisonian-like crisis requiring urgent corticosteroid supplementation.

Treatment of myxoedema coma--factors associated with fatal outcome

Treatment of myxoedema coma has been associated with a high mortality. The causes of death were analysed in this paper by retrospective study of the records of 11 myxoedema coma patients. The serum thyroxine (T4) and triiodothyronine (T3) levels were estimated retrospectively from the amounts of hormone given to the patients by a two-compartment model. Seven patients died and 4 survived. The patients who died were significantly older (78.9 +/- 2.2 years, mean +/- SEM) than those who survived (66.8 +/- 3.7 years). The initial heart rate was lower in the decreased group, but both groups had increased their heart rate on treatment. The surviving patients showed an increase in body temperature during the first 3 days of treatment, in contrast to the patients who eventually died. The deceased patients had received larger amounts of thyroid hormone and had calculated levels of T3 that were nearly twice as high as those of the surviving patients. Old age and a high serum level of T3 are determinants for the fatal outcome of myxoedema coma. Our analysis underscores the importance of using a cautious replacement regimen in myxoedema coma patients.

Serum long acting thyroid stimulator (LATS) and LATS-protector (LATS-P) in Graves' disease associated with localized myxedema

When localized myxedema occurs in Graves' disease, there is often very high serum long acting thyroid stimulator (LATS) activity. However, this association is not invariable and no pathogenetic role for this IgG associated activity is known. Serum LATS protector (LATS-P) is a closely related IgG activity which is present in the majority of cases of untreated Graves' disease. It usually coexists in LATS positive sera in a substantially greater concentration. Its association with localized myxedema has not been studied, nor have serial studies been performed on this activity during the clinical course of the disease. Fourteen patients (13 females, 1 male) with localized myxedema and a history of Graves' disease were examined. In 13 serum LATS was detectable with a wide range of activity from 2.4 to 1,000 units/ml. Serum LATS-P was detected in all including the LATS negative patient with a range of activity from 46 to 4,068 units/ml. Serial studies for at least 2 years were conducted in 8 patients. In two there was no change in either skin lesions or in serum LATS and LATS-P. In 6 the skin lesions partially or completely resolved. In 5 this was associated with statistically significant falls in serum LATS and LATS-P but in one no significant change occurred. The study demonstrated the high prevalence of LATS and LATS-P in localized myxedema. In the sole LATS negative patient there was a high concentration of LATS-P. The role of these activities in the pathogenesis of the disease remains unknown but in serial studies falls in activity were usually associated with clinical improvement.

[Antidiuretic hormone levels (arginine-vasopressin) in cases of peripheral hypothyroidism. 26 cases]

Plasma arginine-vasopressin (AVP) levels were measured by radioimmunoassay in 26 untreated myxoedematous patients and 27 healthy subjects. In 22 patients, in spite low osmolality AVP values were not significantly different from those found in controls, but they were considerably increased in 4 patients with severe myxoedema and very low osmolality. Statistical analysis showed negative correlation between AVP values and osmolality in the patients. On the other hand, no correlation was found between AVP values and aldosterone or plasma renin activity values. These results suggest inappropriate secretion of antidiuretic hormone in myxoedema.

Measurement of thyroxine conversion to triiodothyronine using human lymphocytes. A useful and simple laboratory technique

The deiodination of T4 to T3 has been studied after incubation of whole lymphocytes with different T4 concentrations, followed by a T3 radioimmunological determination performed on unextracted samples. The lymphocytes were isolated from blood from normal volunteers of both sexes and different age classes as well as from myxedematous subjects and patients with low T3 syndrome. The T3 production, in normal subjects, expressed as pmol/10.10(6) cells was 0.41 +/- 0.75 (T4 = 4.10(-7) M, n = 12), 1.43 +/- 0.14 (T4 = 4.10(-6) M, n = 26) and 1.65 +/- 0.29 (T4 = 8.10(-6) M, n = 11). There was no sex or age-related difference. In 3 myxedematous patients the T3 production was lower than the corresponding value obtained in normal subjects. The T3 production in patients with low T3 syndrome was lower than in controls (p less than 0.001); an inverse correlation was found between the T3 production and the serum rT3 levels, whereas no correlation could be found with serum T3 levels.

Factors affecting resolution of pericardial effusions in primary hypothyroidism: a clinical, biochemical and echocardiographic study

Echocardiography detected pericardial effusions in five out of six consecutive untreated patients with severe primary hypothyroidism and suspected myopathy, whereas the chest X-ray suggested only one. During L-thyroxine replacement, serial echocardiograms detected decrease in the size of the effusions in all the patients. This occurred before the serum thyroid stimulating hormone (TSH) levels had significantly changed, although there was a small but significant rise in serum thyroxine. In one patient complete resolution of the effusion occurred before the patient became euthyroid, a previously unreported finding.

Small voltage complexes, T-wave inversion and non-specific T-wave flattening were the commonest electrocardiographic abnormalities noted. The former invariably and the latter two abnormalities frequently, reverted to normal before the patient became biochemically and clinically euthyroid. T-wave inversion in a particular lead, however, did not invariably do so, suggesting that permanent structural change might possibly have occurred.

The plasma creatine kinase (CK) was raised in four patients, and markedly raised at levels usually associated with muscular dystrophy, in two. At the onset of resolution of the pericardial effusions, the total plasma CK had fallen significantly in all patients in whom it was raised.

Serum thyroglobulin and its autoantibody following subtotal thyroid resection of Graves' disease

Thyroid surgery leads to marked changes of the levels of serum thyroglobulin and its autoantibodies in the subsequent 3 postoperative weeks. Furthermore in Graves' disease progression of exophthalmos has sometimes been seen following thyroidectomy. Nineteen medically pretreated patients with Graves' disease and no signs of exophthalmos were studied systematically up to 6 months postoperatively. Nine patients had thyroglobulin antibodies. Mean values rose to 3.5 times pretreatment values within 2 months (P less than 0.001) followed by a gradual fall below pretreatment level after 6 months. None of the antibody negative patients reverted to positive or vice versa. Serum thyroglobulin (n = 10) was elevated preoperatively (mean 309 micrograms/l, SD 251), their values being normalized within 1-2 months (mean 19.4 micrograms/l, SD 7.3). The preoperative serum thyroglobulin correlated to the weight of the removed thyroid tissue (r = 0.87, P less than 0.01). Three patients showed elevated thyroid stimulating hormone after 1 month. Of these, two developed myxoedema, the third remained euthyroid with persistently elevated serum thyroglobulin. None showed recurrence or developed exophthalmos within the period of observation. In spite of rising levels of thyroglobulin antibodies in all patients with antibodies none developed exophthalmos and only one patient with thyroglobulin antibodies had clinical myxoedema.

[Anti-JKa specificity : a rare variety of auto-immune hemolytic anemia (report of a case associated with myxoedema (author's transl)]

The authors report the case of a patient with autoimmune hemolytic anemia, due to anti-KJa antibody, and associated with primary hypothyroidism. They discuss the possible relationship between these two conditions and emphasize the particular hematological pattern related to myxoedema.

Investigation of the usefulness of the plasma adenosine 3' 5' - cyclic monophosphate response to glucagon in thyroid disease

The plasma adenosine 3', 5' - cyclic monophosphate (cyclic AMP) response to 50 micrograms of intravenous glucagon was examined in 14 normal euthyroid subjects, 15 patients with thyrotoxicosis and 5 patients with myxedema. The cyclic AMP responses to 50 micrograms of intravenous glucagon was significantly higher in the hyperthyroid group than in the euthyroid or hypothyroid group. However, the areas of overlap between all three groups were large and there was little relationship between the plasma cyclic AMP response to glucagon and the biochemical assessment of thyroid function. Serial studies of the response to 50 micrograms glucagon were carried out in four patients receiving treatment for thyrotoxicosis. Again, there was not consistent relationship between the plasma cyclic AMP responsiveness to glucagon and the free thyroxine index. It is concluded that although the plasma cyclic AMP response to glucagon is increased in thyrotoxicosis and decreased in myxedema, the variability of this response in thyroid disease precludes its use as a tissue index of thyroid hormone responsiveness.

Somatostatin and the 24 h levels of serum TSH, T3, T4, and reverse T3 in normals, diabetics and patients treated for myxoedema

The influence of somatostatin on serum TSH, 3,5,3′-triiodothyronine (T3), free T3, thyroxine (T4), free T4 and 3,3′,5′-triiodothyronine (reverse T3, rT3) was studied in 5 healthy young subjects, in 7 young patients with juvenile type diabetes on a fixed daily insulin dose, and in 5 patients with treated myxoedema. Blood samples were taken hourly during a 24 h control period and during a 24 h somatostatin infusion period.

Somatostatin infusion obliterated the night increase in serum TSH in all three groups. However, the lower daytime serum TSH was not altered by somatostatin. It has earlier been shown that somatostatin inhibits the TSH secretion induced by TRH. Taken together these findings suggest that the high TSH level at night is induced by a hypothalamic TRH surge, while the lower day level of TSH is quite independent of hypothalamic TRH.

Somatostatin infusion was accompanied by a minor fall in serum T4 in all groups. In normal subjects and diabetics serum free T3 fell 23 ± 6% and 25 ± 6%, respectively, during 24 h somatostatin infusion. In patients with treated myxoedema, serum free T3 was not significantly affected. These results are consistent with a decrease in thyroidal secretion during somatostatin infusion, as the cause for the fall in serum T3 in normal subjects and in patients with diabetes, while the monodeiodination of T4 to T3 in peripheral tissues is unaffected. However, an extrathyroidal effect of somatostatin on iodothyronine metabolism might also exist since serum rT3 increased 49 ± 19% in patients with treated myxoedema. In normal subjects and diabetic patients only a trend towards such a variation was observed.

Transient elevation of serum thyroid hormone concentration after initiation of replacement therapy in myxedema

Measurements of thyroid hormone concentrations in serum are commonly used to determine the proper dose of hormone replacement. We have noted that early in the course of thyroxine (T4) replacement in myxedema, serum T4 concentrations may be transiently elevated before reaching a lower "steady-state" level. This observation is illustrated in a study of six patients. Serum T4, free thyroxine index, and triiodothyronine (T3) rose to peak concentrations at 2 to 6 weeks, 35% to 120% above the values achieved 4 to 8 months later. Values were transiently in the thyrotoxic range in five of the six patients. This phenomenon is most likely due to a decrease in the metabolic clearance rate of the absorbed hormone associated with hypometabolism. Thus, serum T4 and T3 concentrations during the first 6 months of therapy do not reflect the optimal dose of T4 replacement on a long-term basis.

Hyperprolactinemia--a review of recent clinical advances

Since the radioimmunoassay for serum prolactin became available eight years ago, prolactin has become a hormone of considerable clinical interest. An elevated serum prolactin concentration is the most frequent hormone marker for pituitary tumors. Secreted in excess, prolactin causes dysfunction of the hypothalamic-pituitary axis, the gonads, and the adrenal cortex. In women, menstrual disturbances, galactorrhea, infertility, and hirsutism result. Impotence, oligospermia, and decreased libido are common in men. These metabolic abnormalities attributed to prolactin excess are corrected when prolactin concentrations are lowered by either medical or surgical therapy. The availability of effective therapy mandates early recognition and proper management of the patient with hyperprolactinemia.

Pretibial myxoedema: stimulation of mucopolysaccharide production of fibroblasts by serum

We have shown that sera from normal individuals and from patients with pretibial myxoedema contain a factor which simulates mucopolysaccharide biosynthesis in normal human skin fibroblasts cultured in vitro. This factor was present in larger amounts in sera of patients with pretibial myxoedema. The role of growth stimulating factors in serum is reviewed and a hypothesis is put forward that the fibroblast stimulating factor is somatomedin and that its presence in increased amounts in thyroid disease may lead to pretibial myxoedema.

[Studies on the radioreceptor assay of TSH: the properties of TSH-binding inhibitor immunoglobulins (TBII) in patients with Graves' disease (author's transl)]

In the radioreceptor assay system for TSH, serum immunoglobulin G (IgG) from some patients with Graves' disease has been shown to inhibit the binding of labelled TSH to its receptor sites. In order to clarify the properties of these TSH-binding inhibitor immunoglobulins (TBII) in patients with Graves' disease, TBII were measured in sera from 31 untreated and 51 131I-treated patients, and their relation to clinical and laboratory findings was studied. TBII were detected in 18 (60%) out of 31 patients with untreated Graves' disease. TBII levels in these patients correlated well with thyroidal 99mTc uptake at 30 min and also with the grade of epithelial hyperplasia of thyroid follicles. There was no significant correlation between TBII and serum T3, serum T4, free T4 index, antibody titers against thyroglobulin and microsomes, or association of exophthalmos. There were many patients with Graves' disease whose sera contained high TBII levels but no detectable bioassayable thyroid-stimulating activity (LATS), and in these patients a close correlation was observed between serum levels of TBII and bioassayable LATS-protector activity. In patients with Graves' disease who had been treated by 131I from 5 to 17 years before, the incidence of TBII was very low at 20% (10/51). All except two cases having TBII were found to be still thyrotoxic. Thus, TBII were detected in 8 out of 10 thyrotoxic patients and in only 2 out of 18 euthyroid and none of 23 hypothyroid patients. These findings suggest that TBII in patients with Graves' disease were in close association with human thyroid stimulating activity, and that TBII might be useful as an indicator for checking the effectiveness of the treatment.

[Study of blood glucose regulation in 103 cases of adult acquired hypothyroïdism (author's transl)]

Systematic studies of blood glucose regulation have been performed in 103 cases of adult acquired hypothyroïdism. The results were the following: 11 cases of overt diabetes were discovered. The diagnostic was made when fasting blood glucose was superior to 120 mg/100 ml and glucosuria was present. 22 cases of asymptomatic (chemical) diabetes. The diagnosis was based on the abnormalities of the oral glucose tolerance test (OGTT). The criteria were those of Fajans and Conn. In 70 cases the results were normal. The comparison of these results with these obtained in a matched population of normal subjects did not show significative differences. Particularly the proportion of "flat curves" during the OGTT were not higher in cases of hypothyroïdism. Plasma insulin levels were determined in 20 cases of hypothyroïdism during OGTT. The results were the same as in non-hypothyroïd subjects. The abnormalities of glucose regulation observed in hypothyroïdism were not related to sex, age, overweight or cause of the disease. The number of diabetic patients is not significatively more important in cases of hypothyroïdism of immunological origin (especially Hashimoto's disease.

[Primary empty sella associated with peripheral endocrine deficiency: two cases (author's transl)]

The radiological finding of a large sella turcica in long standing peripheral endocrine insufficiency (adrenocortical in one case, thyroid in the other) and the persistence of plasma ACTH and TSH levels above normal despite hormone therapy was first attributed to the consequences of reactive hypersecretion of the corresponding stimulin. The results of scanner studies in one case, and of pathological examination in the other, revealed the presence of primary empty sella syndrom.

Serum T3 and T4 levels in patients with anorexia nervosa showing transient hyperthyroidism during weight gain

Serum thyroxine (T4) and triiodothyronine (T3) levels were measured in a group of thirty-three patients with anorexia nervosa (AN) and compared with twenty-five control women presenting with hirsutism and twenty-one patients with primary myxoedema. T3 levels in the AN patients were significantly lower than in the control subjects and in the patients with myxoedema while T4 levels were significantly higher than in the patients with hypothyroidism but significantly lower than in the control group. Seventeen anorexia patients had further T3 and T4 levels measured following an arbitrary 25% weight gain and both levels had increased significantly. For individual patients, the absolute rise in T3 levels was significantly correlated with the rate of weight gain. Thirteen patients had serial T3 and T4 levels measured during their periods of weight gain. Eight of these subjects showed a gradual rise in T3 levels from subnormal or low normal levels to values in the upper normal range. Four subjects showed a distinct and self limiting overshoot of T3 levels and, associated with this, the patients had clinical features of mild hyperthyroidism.

Delayed healing of mandibular fracture in idiopathic myxedema

Lack of adequate amount of thyroid hormone may interfere with healing. A patient in whom a fracture of the mandible failed to heal in the 2 years following surgical treatment is presented. When thyroid hormone supplementation was introduced, the fracture progressed to union. The physical findings of hypothyroidism and the role of thyroid hormone in healing are discussed.

Effects of substitution with thyroxine on the thyrotrophin (TSH) response to thyrotrophin-releasing hormone (TRH) in severe primary myxoedema and in mild hypothyroidism following prolonged thyrostatic therapy

The evolution of the thyrotrophin (TSH) response after 400 μg thyrotrophin-releasing hormone (TRH) was investigated during recovery of hypothyroidism.

In 14 myxoedematous patients, replacement therapy with thyroxine (T4) caused characteristic changes. Before treatment a relatively blunted pattern with mΔTSH1) of 51.2 ± 30.6 mU/1 was found. Two and 4 weeks after treatment an enhanced response was evolved with values for mΔTSH of 87.7 ± 43.4 and 96.0 ± 48.0 mU/1 (P < 0.02 respectively < 0.01). Comparison of the TSH curve showed significant increases in ΔTSH during the first 4 weeks of treatment at 20, 40 and 60 min compared to corresponding measurements in the basal state.

In 17 overtreated hyperthyroid patients with mild, mostly chemical hypothyroidism the influence of T4 replacement on TSH responses at different TSH levels was studied. At the stage of mild TSH elevation (3–10 mU/1) mΔTSH before and during substitution were 12.6 ± 6.7 and 25.9 ± 15.3 mU/1, respectively (P < 0.01). Moderate TSH elevation (10–25 mU/1) was accompanied by mΔTSH of 25.4 ± 13.4, respectively 44.5 ± 22.9 mU/1 (P < 0.01) while high TSH values (> 26 mU/1) had responses of 39.1 ± 16.0 and 92.5 ± 22.0 mU/1 (P < 0.001). In these patients the initial blunting of TSH responses could not be attributed to the foregoing toxicosis, since follow up during 6–15 weeks of protracted hypothyroidism did not show any tendency to enhancement of relative release (% mΔTSH).

These findings suggest that in the early stage of replacement therapy of hypothyroidism, either pituitary TSH is accumulating or that endogenous TRH is declining.