The preoperative use of iodine solution in thyrotoxic patients prepared with propranolol. Is it necessary?

Despite the numerous reports documenting the safety and efficacy of the use of propranolol, a selective beta-adrenergic blocker, as the sole agent for preoperative preparation of a hyperthyroid patient, many surgeons continue to add a solution containing iodine to the treatment regimen. The rationale for the concomitant use of iodine solution and propranolol is that the iodine solution reduces the amount of propranolol required to make the patient symptomatically euthyroid and that iodine administration reduces the vascularity of the gland, thereby minimizing intraoperative blood loss. To ascertain the validity of these beliefs, we retrospectively reviewed our experience with 42 consecutive hyperthyroid patients who underwent subtotal thyroidectomy. These patients either received propranolol alone (20 patients) or propranolol with iodine solution (22 patients) for preoperative preparation. Comparison of the medication doses, estimated blood loss, and postoperative changes in hemoglobin and hemocrit using the Student's t-test, failed to demonstrate any significant difference between the two treatment protocols (P greater than 0.1). We conclude that the addition of iodine to propranolol for preoperative preparation of hyperthyroid patients does not result in any significant advantage over the use of propranolol alone.

Isolated ACTH deficiency associated with transient thyrotoxicosis and hyperprolactinemia

A 43-year-old woman with isolated ACTH deficiency in association with transient thyrotoxicosis is reported. The initial evaluation revealed that plasma ACTH and cortisol did not respond to corticotropin-releasing hormone (CRH) in the presence of hyperthyroxinemia and hyperprolactinemia. During the replacement therapy with dexamethasone, she developed transient hypothyroxinemia with persistent hyperprolactinemia. Although thyroid open biopsy did not show any evidence of autoimmune thyroiditis or subacute thyroiditis, the data appear to provide other evidence of a possible relationship between acute adrenal insufficiency and transient thyroid dysfunction.

Effects of Lugol's solution on thyroid function in normals and patients with untreated thyrotoxicosis

Thirty-eight normal volunteers and 10 patients with untreated thyrotoxicosis were each given 0.5 ml of Lugol's solution daily for 10 days. On days 0, 5, 10, 15 and 20, serum levels of T4, free T4, T3 and TSH (by sensitive immunoradiometric assay) were measured. In normal subjects, the serum concentrations of free T4 declined significantly at day 10 while TSH levels were significantly increased at days 5, 10 and 15. Serum levels of T4 and T3 did not change significantly. All the observed changes took place within the limits of normal ranges for the hormones mentioned. In contrast, in the thyrotoxic subjects, both T4 and T3 were significantly decreased at days 5 and 10, while serum TSH remained below detection limit (0.14 mU/l) throughout the study. Short exposure to excessive iodide in normal subjects affects T4 and T3 release and this effect could be partially overcome by compensatory increase in TSH. In thyrotoxicosis, lack of compensatory increase in TSH results in rapid decreases in T4 and T3 levels. The integrity of the hypothalamo-pituitary-thyroidal axis may be effectively assessed by measuring TSH response to iodide suppression, using a highly sensitive immunoradiometric assay.

[Transient thyrotoxicosis induced by Japanese kombu]

Iodine-induced thyrotoxicosis (ITT) has not been reported in Japan. We found that excessive intake of Japanese kombu could elicit ITT. Two Japanese women, 42 and 59 years old, developed thyrotoxicosis one month and one year, respectively, after having eaten foods containing 28-140 mg/day of iodine, calculated from their daily diet. Both patients had high concentrations of serum T3, low ratios of serum T3/T4 or T4/r-T3 compared with untreated Graves' disease, and high concentrations of serum inorganic iodine compared with the mean (M +/- SD: 2.05 +/- 0.99 micrograms/dl) plus 2SD in people eating common foods. Their thyrotoxic signs and symptoms disappeared, and their serum T4, T3, r-T3 and T4/r-T3 normalized one month after the prohibition of kombu intake. To clarify the source of iodine, the iodine content of the kombu and the iodine concentration in water in which the kombu was immersed were measured. Ninety-nine % of the iodine was found in water after 15 min boiling. These findings suggest that a daily intake of more than 28 mg/day of iodine in a diet containing kombu might induce ITT.

Effect of acute renal failure on free thyroid hormone levels in a thyrotoxic patient

Acute renal failure in a previously undiagnosed case of thyrotoxicosis was accompanied by a rapid and spontaneous decline in thyroid hormone levels. Over a 2-week period, free triiodothyronine and thyroxine fell to the low levels seen in euthyroid patients with end-stage renal disease. Thyrotropin levels remained undetectable throughout, suggesting impairment of the pituitary-thyroid axis at the level of the thyroid gland. This may represent an important beneficial adaptation to severe illness and could explain the virtual absence of hyperthyroidism in renal failure patients.

Rapid effectiveness of prednisone and thionamides combined therapy in severe amiodarone iodine-induced thyrotoxicosis. Comparison of two groups of patients with apparently normal thyroid glands

Treatment of amiodarone iodine-induced thyrotoxicosis is often unsuccessful. Nevertheless, severe forms require a rapidly efficient therapy. Twelve patients with severe amiodarone iodine-induced thyrotoxicosis, as demonstrated on clinical and biological findings, were studied. After amiodarone withdrawal, 6 patients (group A) were treated with thionamides alone (carbimazole 60 mg daily and benzylthiouracile 1.5 g daily), and 6 patients (group B) received in addition to the same antithyroid drugs prednisone, 0.50 to 1.25 mg/kg/day for 40 days; in group A, T4 levels did not change over the study period of 40 days; T3 levels decreased only after 30 days; clinical status did not improve. In group B: T3 and T4 levels decreased dramatically at 10 days of treatment, to values significantly lower than in group A; clinical improvement occurred mainly in patients treated with high doses of prednisone; elevated thyroglobulin levels diminished rapidly. Improvement was maintained after cessation of prednisone. The rapid effect of prednisone suggests an impairement of proteolysis of thyroglobulin possibly due to a lysosomal action.

[Effect of merkazolyl on the level of thyrostimulating immunoglobulins of the blood in patients with diffuse toxic goiter]

A study was made of the level of thyrostimulating immunoglobulins (TSI) in the blood of 31 untreated patients with diffuse toxic goiter (DTG). The effect of thiamazole applied at a daily dose of 30-60 mg for 3-4 weeks on a TSI level was investigated in 18 patients. The level was assessed by an increase in a cAMP level in thyroid paired lobes after incubation with immunoglobulins of DTG patients. The basal level of TSI does not correlate with the level of blood thyroxin, thyroid iodine absorptive capacity of DTG patients, and severity of thyrotoxicosis. Thiamazole produces a different effect depending on a degree of severity of thyrotoxicosis decreasing a TSI level in patients with disease of average severity and not changing the level in severe thyrotoxicosis.

Normal cellular uptake of thyroxine from serum of patients with familial dysalbuminemic hyperthyroxinemia or elevated thyroxine-binding globulin

To determine whether thyroid hormone-binding proteins in serum, particularly albumin, facilitate the transfer of T4 into human tissues, we studied cellular T4 uptake (CT4) by human liver (Hep G2) cells from medium containing serum from subjects with familial dysalbuminemic hyperthyroxinemia (FDH) and acquired and familial T4-binding globulin (TBG) excess and patients with normal T4-binding to albumin and normal TBG concentrations. Serum from nine subjects with FDH whose mean serum total T4 (TT4) concentration was 203 +/- 27 nmol/L were matched for TT4 concentrations with serum from nine subjects with acquired TBG excess (TT4, 201 +/- 23 nmol/L) and nine subjects with thyrotoxicosis and normal TBG concentrations (TT4, 205 +/- 28 nmol/L). The subjects' CT4 results were compared to their serum free T4 concentration, measured by equilibrium dialysis (DT4), and their serum free T4 index (FT4I) value. The mean serum DT4 value for the subjects with FDH (23 +/- 5 fmol/L) and those with TBG excess (23 +/- 3 fmol/L) were normal, whereas it was elevated (44 +/- 9 fmol/L; P less than 0.001) for the thyrotoxic patients with normal TBG concentrations. The mean CT4 value also was normal for the subjects with FDH (37.7 +/- 4.9 fmol/plate) and those with TBG excess (36.6 +/- 4.6 fmol/plate), but was elevated for the thyrotoxic patients (62.3 +/- 11.2 fmol/plate; P less than 0.001). In all three groups studied, the relationship between individual CT4 and DT4 values was similar to that previously found in subjects with no T4-binding protein abnormalities. The mean serum FT4I value was lower for the subjects with acquired TBG excess (111 +/- 22) than for the subjects with FDH (133 +/- 22; P less than 0.05), and it was much higher for the subjects with thyrotoxicosis (221 +/- 31; P less than 0.001). In the subjects with FDH and those with thyrotoxicosis the normal relationship between CT4 and FT4I was maintained, while in the subjects with acquired TBG excess, FT4I values were lower than expected. In seven of the nine subjects with TBG excess, the abnormality was associated with conditions known to increase its sialic acid content: hepatitis (one subject), pregnancy (four subjects), and estrogen therapy (two subjects). The CT4 values were similar in nine subjects with acquired TBG excess (seven pregnant women and two subjects with chronic active hepatitis) and five subjects with familial TBG excess (34.8 +/- 4.3 vs. 34.0 +/- 8.6 fmol/plate, respectively).(ABSTRACT TRUNCATED AT 400 WORDS)

[Effect of thyroid hormones on calcitonin secretion]

A study of 140 patients with diffuse toxic goiter showed phasic change in plasma calcitonin concentration and blood calcitonin activity: an increase in these indices at early stages of disease with a subsequent decrease in a severe form of thyrotoxicosis. Basal calcitonin secretion by fragments of the thyrotoxic thyroid was much higher than that euthyroid gland. In incubation of paranodal tissue of the thyroid of patients with nodular euthyroid goiter and fragments of the thyroid of patients with thyrotoxicosis of moderate severity with thyroxin at concentration 10(-8) M the level of calcitonin secretion considerably increased, concentration 10(-6) M was ineffective. The thyroid taken peroperatively from patients with diffuse toxic goiter with thyrotoxicosis of a severe form turned out nonreactive with relation to thyroxin concentration 10(-8) M. Basal calcitonin secretion in the study group was within control values. Thyroxin showed the properties of a calcitonin-secretion stimulator. Signs of depletion of the thyroid calcitonin-producing capacity were revealed in the course of development of diffuse toxic goiter.

[Dynamic thyroid function after the surgical treatment of patients with diffuse toxic goiter]

The time course of thyroid function and hypophyseal thyrotropic activity were investigated in 182 patients with diffuse toxic goiter of severe and moderately severe forms of thyrotoxicosis before operation and in short- and long-term periods after operation using radioimmunoassay in a hospital and outpatient clinic. The determination of blood T3, T4 and TSH at the height of clinical manifestations of thyrotoxicosis and before operation was shown to reflect the gravity of disease and could serve as a diagnostic test of the efficacy of preoperative preparation. A T4 concentration index varied at different time after operation. A considerable decrease in blood TSH on the first days after the operation and its rise in the following 6 mos. resulted from the patients' adaptation to new conditions and were of transient nature in the overwhelming majority of the patients. Final assessment of the thyroid and pituitary function was possible only 12 mos. after operation.

Why are the sensitive TSH assay and TRH stimulation test frequently low in very old euthyroid subjects?

Twelve healthy clinically euthyroid subjects 80 years and over were compared with 19 young controls to determine if the sensitive TSH test was more specific for hyperthyroidism in the elderly than the TRH stimulation test. Four of the 12 elderly subjects had a sensitive TSH level below the lower limit of normal for young subjects and four elderly subjects had a TSH rise of less than five IU after injection of 200 micrograms of TRH. Neither test is specific for hyperthyroidism in the elderly. There was a highly significant correlation between the sensitive TSH levels and the TSH rise after TRH stimulation in the old subjects but not in the young. This may be further evidence of an age related impairment in the hypothalamo pituitary-thyroid axis.

A laboratory and clinical evaluation of an immunochemiluminometric assay of thyrotropin in serum

We evaluated an immunochemiluminometric assay for human thyrotropin. A chemiluminescent acridinium ester is used as a label, with magnetic-particle separation. The lower limit of detection of the assay (mean + 3 SD of the zero standard) was 0.07 milli-int. unit/L, with a working range of 0.5 to greater than 60.0 milli-int. units/L. Assay accuracy was good as judged from analytical recovery, analysis of external quality-assessment samples, and comparison with an enzyme-amplified immunoassay. There were no significant interferences or cross-reactivities. Twenty-four samples assayed showed aggregation of the magnetic particles. On re-assay, four of these samples showed a significant increase in the measured TSH by the luminescence assay. Assay time for 60 tubes was approximately 3.5 h with the use of a semi-automated luminometer. The reference interval, determined from data on 144 healthy euthyroid subjects, was 0.3-4.0 milli-int. units/L. Sixteen of 19 thyrotoxic patients showed clearly suppressed concentrations of thyrotropin in serum.

Thyrotoxic periodic paralysis

We present the case of a 21-year-old man who presented to the emergency department with an episode of profound weakness due to thyrotoxic periodic paralysis, a syndrome of muscular weakness occurring in patients with hyperthyroidism. Prior to the diagnosis, the patient was treated with a parenteral tranquilizer. When hypokalemia was discovered, potassium was administered, resulting in the development of hyperkalemia. Episodes of thyrotoxic periodic paralysis are usually self limited, and recovery of motor strength is complete. However, potassium is frequently administered to hasten recovery and prevent cardiac arrhythmias and respiratory arrest. Serum potassium must, therefore, be monitored carefully in these patients during treatment.

Problems with asthma following treatment of thyrotoxicosis

We describe two cases of asthma associated with concomitant thyrotoxicosis where initial improvement followed antithyroid treatment. Relapse of asthma on thyroxine replacement was accompanied by subclinical hyperthyroidism with elevated levels of triiodothyronine. This emphasizes the need to follow up asthmatic patients closely for biochemical relapse following treatment of thyrotoxicosis.

Familial generalised resistance to thyroxine: case study

We describe the clinical features of members of a family with an atypical form of thyroid hormone resistance syndrome, affecting thyroxine predominantly. Relevant diagnostic clinical and biochemical investigations are outlined and discussed.

Sodium ipodate in the treatment of toxic diffuse goiter. Short-term and long-term effects on thyrotoxicosis

Iodinated radiocontrast medication has been successful in the treatment of thyrotoxicosis when used for short periods up to 21 days, but experience with long-term use is lacking. In the first part of this study, a group of seven patients each taking 1.5 g. sodium ipodate daily was observed for 21 days and compared to a similar group of seven thyrotoxic patients taking 400 mg. propylthiouracil (PTU) daily. Sodium ipodate brought about a more significant decrease in serum total T3 and T4 levels, and more prominent increase in reverse T3 levels in the first ten days of the treatment. In the second part, a group of seven patients with thyrotoxicosis were given sodium ipodate, 1.5 g, daily for 20 days and 0.75 g. thereafter and were compared to a similar group of seven patients who took PTU, 300 mg. daily for the first 20 days and 150 mg. daily afterwards. Serum thyroid hormone levels decreased in both groups at the end of the first month of treatment, but rose again, along with worsening of symptoms, in five patients on ipodate treatment. Therefore, sodium ipodate, an iodinated radiocontrast agent is unable to control thyrotoxicosis for longer than a month.

Skeletal muscle and whole body protein turnover in thyroid disease

The effects of disturbances of thyroid hormone secretion on leg and whole body amino acid and protein metabolism have been investigated in seven patients with untreated thyrotoxicosis and eight patients with untreated hypothyroidism; the results were compared to those obtained in 11 normal control subjects. After treatment, the patients were restudied. Arterio-venous exchanges of tyrosine and 3-methylhistidine across leg tissue in the post-absorptive state were used as indices of net protein balance and myofibrillar protein breakdown, respectively. Whole body protein turnover was measured using stable isotope labelling techniques with 1-[1-13C] leucine. Efflux of tyrosine from leg tissues was six-fold greater in patients with untreated thyrotoxicosis than in normal control subjects (-19.39 +/- 2.21 vs. -4.20 +/- 0.31 nmol 100 g-1 leg tissue min-1, P less than 0.005, mean +/- SEM), but 3-methyl-histidine efflux was not significantly different (-0.11 +/- 0.03 nmol 100 g-1 leg tissue min-1 vs. 0.14 +/- 0.02 nmol 100 g-1 leg tissue min-1). After treatment, when the thyrotoxic patients became euthyroid, tyrosine efflux was normalized (at -4.94 +/- 0.84 nmol 100 g-1 leg tissue min-1) and 3-methylhistidine efflux was unchanged. In hypothyroid patients, neither tyrosine nor 3-methylhistidine effluxes were significantly different from those in normal subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Ten commercial kits compared for assay of thyrotropin in the normal and thyrotoxic range

I developed a standard procedure for assessing sensitivity, intra-assay precision, parallelism of sample dilutions, and assay drift, using a single trial assay kit. I used this to compare the performance of 10 commercial kits with an in-house radioimmunoassay for human thyrotropin. No one kit stood out as clearly superior overall. Differences in calibration between kits were evident in a comparison of thyrotropin concentrations measured in clinical samples, and by direct comparison of standards from different kits in a single assay. However, all kits gave clinically consistent results with respect to their published normal reference interval. Moreover, the performance of human thyrotropin assay kits has improved during the 14 months of this study.

Hypothalamic-pituitary-testicular axis in patients with hyperthyroidism

To test whether chronic thyroid hormone excess influences the hypothalamic-pituitary-testicular axis, 8 hyperthyroid men were given two identical intravenous GnRH tests. The first test was performed before any treatment had been instituted, the second 6-13 months later, when medical treatment had made the patients euthyroid. Although basal serum luteinizing hormone (LH), follicle-stimulating hormone (FSH) and testosterone (T) levels were of similar magnitudes before and after the medical treatment, LH and FSH responsiveness to gonadotropin-releasing hormone (GnRH), as reflected by the hormone incremental areas (U/l X min), were significantly larger in the thyrotoxic state compared with the euthyroid state (LH incremental areas: 3,999 +/- 665 vs. 2,640 +/- 430, p less than 0.02; FSH incremental areas: 825 +/- 193 vs. 542 +/- 98, p less than 0.05). Furthermore, serum T increased significantly in response to GnRH when the patients were hyperthyroid (T incremental area: 162 +/- 51, p less than 0.02), but failed to do so when they were euthyroid (T incremental area: 92 +/- 53, NS). These results imply that chronic thyroid hormone excess makes the pituitary gonadotrophs 'hypersensitive' to exogenous GnRH. This may in turn explain why human Leydig cells respond more powerful to exogenous GnRH in thyrotoxic patients than in euthyroid subjects.

[The role of thyroid hormones in the regulation of electric stability of erythrocyte membranes in rats]

A method of electric breakdown was used for a study of electric stability (durability) of the membranes of erythrocytes isolated from the blood of normal rats and rats with hypo-, hyperthyrosis and thyrotoxicosis. Erythrocytic membrane electric durability was shown to depend on the hormonal status. In particular, an increase in the potential of breakdown of erythrocytes of hyperthyroid rats was shown in comparison with the characteristics of erythrocytes of the other studied populations. Judging by the test thyrotoxicosis was accompanied by a decrease in a degree of physical homogeneity of erythrocytic membranes. There were no differences in electric durability between erythrocytes of normal and hyperthyroid animals.

Plasma levels of atrial natriuretic peptide in hyperthyroidism

We measured plasma atrial natriuretic peptide (ANP) levels in 17 patients with newly diagnosed thyrotoxicosis. ANP was elevated compared to a group of healthy controls and fell to normal after treatment. Plasma cyclic guanosine monophosphate was also raised in untreated patients. Elevated circulating levels of ANP may play a part in the haemodynamic changes of hyperthyroidism.