Effect of oral glucose feeding on thyroid hormone action in human mononuclear blood cells

The effect of glucose feeding on serum concentrations of thyroid hormones, nuclear T3 binding and thyroid hormone stimulated oxygen consumption and glucose uptake was evaluated. Six persons without thyroid diseases were fed exclusively glucose (2500 kcal/day) for two days. Glucose feeding resulted in the following serum hormone levels (before vs after glucose feeding) T3: 1.07 vs 1.16 nmol/l (p less than 0.05); FT4I: 76 vs 102 a.u. (p less than 0.05) and TSH: 1.48 vs 1.14 mU/l (n.s.). Nuclear T3 binding decreased after glucose feeding; before: maximal binding capacity (MBC) 1.3 +/- 0.5 fmol/100 ug DNA, MBC after glucose feeding: 0.8 +/- 0.2 fmol/100 ug DNA (p less than 0.05). The Ka's were identical in both groups before glucose, Ka: 4.2 +/- 1.2 x 10A10 l/mol, after glucose, Ka: 3.5 +/- 1.2 x 10(10) l/mol. Conversely did glucose feeding increase thyroid hormone stimulated oxygen consumption by approximately 100% and thyroid hormone stimulated glucose uptake by approximately 200%. In conclusion, our results show that glucose feeding 1) increases serum T3 levels, 2) decreases nuclear T3 binding, 3) enhances thyroid hormone stimulated oxygen consumption and glucose uptake.

Observer variation in the scintigraphic diagnosis of solitary cold thyroid lesions

In order to evaluate the reproducibility of the diagnosis of solitary cold thyroid lesions, two specialists in nuclear medicine and two specialists in endocrinology independently twice read 240 thyroid 99mTc pertechnetate scintigrams. No significant difference or interaction between the results obtained from the right and the left lobe was found. A solitary cold lesion was diagnosed in 100 of the 480 lobes; however, in only 30 did all four observers agree upon the diagnosis. Interobserver variation was determined by pairwise comparison of observers. The observed agreement was between 0.91 and 0.94. After adjusting for expected chance agreement, kappa values between 0.57 and 0.70 were found. Intraobserver variation was smaller than interobserver variation, revealing agreement rates of 0.93-0.96 and kappa values between 0.71 and 0.77. Agreement was related to large lesions, lesions located centrally in the lobe, and ovoid-shaped lesions. Clinicians should be aware to what extent they can rely on the information they use in their decisions. The considerable inconsistency in the evaluation of cold lesions on thyroid scintigrams should be taken into consideration, and calls in question the value of using thyroid scintigrams for deciding whether a patient should be referred for operation or biopsy.

Renal tubular reabsorption of sodium and water during infusion of low-dose dopamine in normal man

1. Using the renal clearance of lithium (CLi) as an index of proximal tubular outflow of sodium and water, together with simultaneous measurements of effective renal plasma flow, glomerular filtration rate (GFR) and sodium clearance (CNa), renal function and the tubular segmental reabsorption rates of sodium and water during dopamine infusion (3 micrograms min-1 kg-1) were estimated in 12 normal volunteers. 2. CNa increased by 128% (P less than 0.001). Effective renal plasma flow and GFR increased by 43% (P less than 0.001) and 9% (P less than 0.01), respectively. CLi increased in all subjects by, on average, 44% (P less than 0.001). Fractional proximal reabsorption [1-(CLi/GFR)] decreased by 13% after dopamine infusion (P less than 0.001), and estimated absolute proximal reabsorption rate (GFR-CLi) decreased by 8% (P less than 0.01). Absolute distal sodium reabsorption rate [(CLi-CNa) x PNa, where PNa is plasma sodium concentration] increased (P less than 0.001), and fractional distal sodium reabsorption [(CLi-CNa)/CLi] decreased (P less than 0.001). 3. It is concluded that natriuresis during low-dose dopamine infusion is caused by an increased outflow of sodium from the proximal tubules that is not fully compensated for in the distal tubules.

Overall renal and tubular function during infusion of amino acids in normal man

1. Amino acids have been used to test renal reserve filtration capacity. Previous studies suggest that amino acids increase glomerular filtration rate (GFR) by reducing distal tubular flow and tubuloglomerular feedback activity. 2. Glomerular function and the renal tubular handling of sodium during infusion of amino acids was studied in 12 normal volunteers. 3. Clearance of sodium (CNa) was unchanged. Effective renal plasma flow increased slightly, but significantly, by 9% (P less than 0.05). GFR was increased by 13% (P less than 0.001). Clearance of lithium (CLi) (used as an index of proximal tubular outflow) increased by 38% (P less than 0.001). Calculated absolute proximal reabsorption (GFR-CLi) remained unchanged. Fractional proximal reabsorption [1-(CLi/GFR)] was decreased by 10% (P less than 0.001). Calculated absolute distal sodium reabsorption [(CLi-CNa) x PNa, where PNa is plasma sodium concentration] increased by 40% (P less than 0.001). Plasma renin concentration did not change significantly. 4. The results suggest that amino acids increase GFR by a primary effect on renal haemodynamics or, less likely, by reducing the signal to the tubuloglomerular feedback mechanism. The increase in proximal tubular outflow was compensated for in the distal tubules, so that the sodium excretion rate remained unchanged.

Observer variation in the assessment of scintigraphy of the thyroid gland

In order to determine observer variation in the assessment of thyroid scintigrams two specialists in nuclear medicine and two specialists in endocrinology independently evaluated 240 thyroid pertechnetate scintigrams twice, and assessed a number of variables concerning size and isotope uptake. The observed agreement between pairs of observers for the variables ranged from 0.70 to 0.98. By the use of the kappa coefficient the observed agreement was adjusted for change agreement. Kappa can variate from -1 (total disagreement) to +1 (perfect agreement). Kappa values between 0.29 and 0.86 were found. In the intraobserver study the observed agreement ranged from 0.83 to 0.99 resulting in kappa coefficients between 0.53 and 0.96. Thus the level of agreement in the present study was "fair to substantial" for agreement in the interobserver part and "substantial to almost perfect" for agreement in the intraobserver part. No difference was found in the level of agreement between the nuclear specialists and the endocrinologists. Although the treatment of patients is based on knowledge of the case histories and clinical and laboratory findings the high degree of observer variation may lead to misclassification of a number of patients with thyroid disease and subsequently a less optimal choice of treatment.

Frequency of thyroiditis and postpartum thyroiditis in a 10-year consecutive hyperthyroid Danish population

In a retrospective study 716 consecutive newly diagnosed and untreated hyperthyroid patients were examined in regard to the frequency of silent thyroiditis and postpartum thyroiditis. Six patients (0.8%) had possible silent thyroiditis (24-hour radioiodine uptake less than or equal to 5% and hyperthyroidism without anterior neck pain). None occurred within one year postpartum. We conclude that silent thyroiditis is a rare cause of hyperthyroidism in our thyroid clinic. The fact that none occurred postpartum suggests that postpartum thyroiditis is oligosymptomatic and that screening programmes are needed if one wants to diagnose the earliest phases of this condition.

Relationship between serum thyroglobulin, thyroid volume and serum TSH in healthy non-goitrous subjects and the relationship to seasonal variations in iodine intake

In order to investigate the interrelationship between serum thyroglobulin (Tg), thyroid volume and serum TSH by a sensitive method, 176 healthy euthyroid non-goitrous subjects were studied. Furthermore the seasonal influence, assuming seasonal differences in iodine intake in Denmark, was studied in 13 healthy male volunteers. A weak correlation between serum Tg and thyroid volume was found only in female non-goitrous subjects. No correlations between serum Tg, thyroid volume, free T4 and free T3 indices, T3/T4 ratio, serum TSH by sensitive method or age were seen. Thyroid volume was increased (P less than 0.01) during the winter without any change in thyroid function or TSH level, whereas serum Tg level in these subjects was significantly lower (P less than 0.02) during the winter compared with the summer. In conclusion, serum Tg showed no correlation with either thyroid volume, super-sensitive TSH or thyroid function in a population of non-goitrous subjects in Denmark. The lack of correlation between increased thyroid volume and decreased serum Tg during the winter compared with the summer is unexplained. It might be hypothesised that short-term changes in iodine intake induce only colloid accumulation (i.e. increased thyroid volume) without changes in the glandular secretion of Tg or thyroid hormones.

Differential effect of continuous administration of beta-adrenoceptor antagonists on antipyrine and phenytoin clearance

1. Antipyrine (1000 mg orally) clearance was studied 3 days before treatment with either atenolol (50 mg twice daily), metoprolol (100 mg twice daily), propranolol (80 mg twice daily) or placebo, and at day 5 and 18 during treatment. Phenytoin (100 mg intravenously) clearance was measured on days 0, 7 and 21 during treatment. 2. Antipyrine clearance was decreased by about 20% after 5 days of treatment with either propranolol or atenolol and this decrease persisted after 18 days of treatment. Antipyrine clearance did not change during treatment with either metoprolol or placebo. Phenytoin clearance did not change during any of the treatments.

Influence of rifampicin on thyroid gland volume, thyroid hormones, and antipyrine metabolism

The influence of rifampicin (450 mg/day for 28 days) on the hepatic microsomal enzymes and thyroid function variables were investigated in 13 healthy male volunteers. After 14 and 28 days of treatment a significant increase in median thyroid volume (determined ultrasonically) was demonstrated (20 ml, range 13-28 before; 26 ml, range 18-48 at day 14, and 24 ml, range 17-40 at day 28) (p less than 0.01). A significant decrease in median serum free T4 index levels was seen (94.1 arbitrary units, range 80.1-123.4 before treatment; 86.8, range 71.7-102.0 at day 14, and 85.3, range 65.5-131.3 at day 28) (p less than 0.01). Serum T4, T3, T3 resin uptake, free T3 index and TSH levels were not significantly altered. Hepatic microsomal enzyme activity assessed by antipyrine clearance was significantly increased (approximately by 85%) at day 14 and 28, whereafter it normalized. The study supports the hypothesis that the increase in thyroid volume after treatment with rifampicin and other hepatic enzyme system inducers (e.g. phenytoin and carbamazepine) is a compensatory mechanism caused by an increased hepatic degradation of thyroid hormones.

Crossover comparison of cibenzoline and quinidine in ambulatory patients with chronic ventricular arrhythmias

This study was designed to compare the efficacy and safety of cibenzoline and quinidine in ambulatory patients with ventricular arrhythmias. Following washout of previous antiarrhythmic treatment, a 48-h ambulatory electrocardiographic (ECG) recording was obtained. Twenty-seven patients were screened, of whom 20 met the entry criteria of greater than or equal to 30 ventricular premature beats (VPBs)/h. Cibenzoline was started at 130 mg every 12 h and was increased to 160 mg every 12 h if necessary. Quinidine was started at 300 mg every 6 h and was increased to 400 mg every 6 h if necessary. Treatment was assessed by 24-h ambulatory ECG recording. Efficacy was defined as greater than 75% reduction in single VPBs, greater than 90% reduction in paired VPBs, and total abolition of ventricular tachycardia events. A 7-day washout with repeat 24-h ambulatory ECG recording to document return of ventricular arrhythmias was required prior to crossover. Efficacy was documented in 9 of 20 (45%) patients receiving cibenzoline and in 9 of 20 (45%) patients receiving quinidine. Response to cibenzoline 130 mg every 12 h was documented in 8 of 20 (40%) patients and in 1 of 11 (9%) patients receiving cibenzoline 160 mg every 12 h. Response to quinidine 300 mg every 6 h was documented in 8 of 20 (40%) patients and in 2 of 6 (33%) patients receiving 400 mg every 6 h. Dose-limiting side effects occurred in 1 of 20 (5%) patients receiving cibenzoline and in 7 of 20 (35%) patients receiving quinidine. Cibenzoline and quinidine are equal in efficacy, but cibenzoline is significantly better tolerated.

Pituitary-cell autoantibody diversity in sera from patients with untreated Graves' disease

Sera from 22 untreated patients with recently diagnosed Graves' disease (GD) were screened in an immunocytochemical tissue assay for presumptive pituitary IgG autoantibodies, as defined by the presence of immunoreaction with rat and swine pituitary cell types. Forty four patients with Hashimoto's thyroiditis (HT) and 97 healthy subjects were also studied. Anti-pituitary antibodies were found in 14 of the 22 GD sera (64%). Of these, 6 sera reacted with cytoplasmic components of growth hormone (GH) cells, 3 with prolactin (PRL) cells, and 5 with both GH and PRL cells. Yet, none of the immunoreactive sera reacted with human GH, bovine PRL or TSH in dot-blot assays and absorption studies. Anti-pituitary antibodies also occurred in 4 of the 44 HT patients (9.1%) and in 9 of the 97 healthy subjects (9.2%). The frequency of sera revealing anti-pituitary antibodies was significantly higher in patients with GD compared to the groups of HT patients (P less than 0.00005), and healthy subjects (P less than 0.00005). Healthy subjects and patients with HT had a similar frequency of anti-pituitary antibodies (P = 1.0000). These data demonstrate that in thyroid autoimmune conditions antibodies reactive with cytoplasmic components of pituitary GH/PRL cells, may be present in sera from patients with GD. The pathological importance of this observation is at present unknown.

Suppressed natural killer cell activity in patients with euthyroid Graves' ophthalmopathy

The purpose of the present study was to determine whether patients with euthyroid Graves' exophthalmopathy have an impaired NK cell function compared to patients with Graves' hyperthyroidism and healthy controls. The NK cell activity measured against K562 target cells was significantly suppressed (p less than 0.01) in patients with euthyroid Graves' ophthalmopathy, whereas the NK cell activity of patients with Graves' hyperthyroidism was not. Although interferon-alpha, interleukin-2 and indomethacin significantly enhanced (p less than 0.01) the NK cell activity in all three groups, none of these agents fully restored the defective NK cell activity in euthyroid Graves' ophthalmopathy. The concentrations in the blood of large granular lymphocytes and CD16 positive cells did not differ between the three groups, furthermore an immunosuppressive serum factor was not detected. The number of effector/target cell conjugates did not differ between patients and controls, whereas the interferon-alpha induced production of a soluble natural killer cytotoxic factor (NKCF) with specificity for NK sensitive target cells was suppressed in patients with Graves' euthyroid ophthalmopathy. We conclude that one of the mechanisms underlying the defective NK cell activity in patients with euthyroid ophthalmopathy may be an impairment of the release of NKCF from the NK cells.

Tetracycline for sclerosis of thyroid cysts. A randomized study

In a prospective study, 53 consecutive patients with solitary thyroid cysts were randomized to ultrasonically guided cyst aspiration and subsequent flushing with isotonic saline (n = 30) or tetracycline hydrochloride (n = 23). The patients were followed up clinically and ultrasonically 1, 3, 6, and 12 months after treatment. If the cyst recurred, a repeated treatment was offered. Cure was defined as the absence of any residual nodule and an ultrasonic cyst volume of less than 1 mL 12 months after the last treatment. During follow-up, two patients without recurrence after saline treatment and six patients without recurrence after tetracycline treatment developed solid cold nodules. Fourteen (47%) of 30 patients in the saline group and ten (43%) of 23 patients in the tetracycline group were cured (not statistically significant). Tetracycline does not seem to offer any advantage over isotonic saline in the treatment of thyroid cysts, and some of these patients still need thyroid surgery.

Stroke in thyrotoxicosis with atrial fibrillation

Chronic atrial fibrillation is associated with an increased risk of stroke. In elderly patients with thyrotoxicosis, atrial fibrillation is frequently encountered, and the true risk of cerebrovascular events in these patients is controversial. We retrospectively studied 610 patients with initially untreated thyrotoxicosis, 91 (14.9%) of whom had atrial fibrillation, with the highest frequency in the elderly patients. The risk of cerebrovascular events, with special attention to the first year after the diagnosis of thyrotoxicosis, was calculated using logistic regression methods with age, sex, and atrial fibrillation as independent variables. Only age was an important risk factor (p less than 0.005), whereas sex and atrial fibrillation were not significant (p = 0.09 and p = 0.17, respectively) as independent risk factors. This is contrary to other studies of patients with thyrotoxic atrial fibrillation, and the need for further clarification of this issue is clear. From our study the indication for prophylactic treatment with anticoagulants for prevention of stroke in thyrotoxic atrial fibrillation seems doubtful, especially as no controlled studies of such treatment in patients with atrial fibrillation are currently available.

The relationships between serum T3 index, thyroid volume, and thyroid stimulating, TSH receptor binding and thyroid growth stimulating antibodies in untreated Graves' disease

This study represents an international double-blind collaborative study of abnormal immunoglobulin activity in untreated Graves' disease. Laboratories in two countries participated in a comparison of thyrotrophin binding inhibiting (TBII), thyroid stimulating (TSAb), and growth stimulating (TGI) immunoglobulins with clinical data, including ultrasonically measured thyroid size. The correlation between TGI and thyroid volume (n = 25, Rs = 0.54, P less than 0.05) and the fact that 9 of 10 patients with high range TGI values had large goitres establish the relationship between TGI and goitre, confirming that the in-vitro activity of these antibodies is related to an in-vivo action. In addition, both TBII and TSAb correlated with serum free T3 indices (TBII: n = 60, Rs = 0.46, P less than 0.001, and TSAb: n = 60, Rs = 0.64, P less than 0.001). Moreover, both TBII and TSAb correlated with thyroid volume (TBII: n = 60, Rs = 0.37, P less than 0.01, and TSAb: n = 60, Rs = 0.41, P less than 0.01) suggesting that these antibodies are also important in development of goitre in Graves' disease. Finally, some correlation between the antibodies was observed. TBII correlated with TSAb (n = 60, Rs = 0.47, P less than 0.001), and in the 16 patients with positive TGI results, this activity correlated with TBII (Rs = 0.54, P less than 0.05), but not with TSAb. Also some cases were found with corresponding high range TBII and TGI, while negative for TSAb, suggesting a close relationship between the in-vitro measurement of TSH binding and TGI.

Does prophylactic thyroxine treatment after operation for non-toxic goitre influence thyroid size?

In order to evaluate the influence of thyroxine treatment on thyroid volume after thyroidectomy for non-toxic goitre 110 consecutive patients were randomised to receive thyroxine (150 micrograms daily) or no treatment three months after operation. Thyroid volume determined by ultrasonography did not differ significantly between the two groups one year after operation. Nevertheless, a similar decrease in volume was seen from three to 12 months postoperatively in the thyroxine treated and no treatment groups (median 18 (range 8-70) ml to 16 (range 7-57) ml, and median 20 (range 9-72) ml to 17 (range 8-58) ml, respectively). Three patients (two given thyroxine) had recurrence of goitre within the observation period of one year. In this series thyroid volume decreased during the first postoperative year independently of thyroxine treatment. Hence it seems questionable whether postoperative thyroid function studies can identify patients at risk of recurrence of goitre after operation for non-toxic goitre and whether routine postoperative treatment with thyroxine is justifiable.

Serum thyroglobulin in chronic renal failure--effects of haemodialysis

The influence of chronic renal failure (CRF) on serum thyroglobulin concentration (Tg) was investigated in 37 patients (29 on haemodialysis) and compared with results obtained from matched controls. Serum Tg did not differ significantly between CRF patients not on haemodialysis: median 24.1 micrograms/l, (range 2.5-47.0) and controls: median 23.6 micrograms/l, (range 2.1-53.0). Patients on haemodialysis had a significantly lower serum Tg level: median 11.4 micrograms/l (range 2.1-54.0) compared to controls (p less than 0.01) but no change in serum Tg level could be demonstrated after a single haemodialysis. A possible explanation for the low serum Tg level in patients with CRF on haemodialysis is decreased production parallelling the decreased production rate of T4 and T3. Since CRF patients not on haemodialysis had an unchanged serum Tg level compared to controls, haemodialysis was associated with small changes in serum Tg level, and since none of the patients had a serum Tg value above the upper reference limit we conclude that these changes were not of a magnitude likely to cause misinterpretation of results in routine clinical situations.

Micturition pattern in hyperthyroidism and hypothyroidism

Micturition pattern was investigated in 61 consecutive patients with thyroid disease. The patients were divided into three groups: hyperthyroid, hypothyroid, and euthyroid. Micturition pattern was examined after the first visit to the hospital and again six months later, when thyroid function had been restored to normal. Hyperthyroid patients had significantly increased micturition frequency as well as nocturia compared with their own control group when euthyroid (p less than 0.01). Hypothyroid patients had reduced micturition frequency compared with their own control group (p = 0.05). No significant changes were found in the euthyroid group. Which mechanisms might be responsible for the relationship between thyroid function and micturition pattern is debatable, and calls for further urodynamic and electrophysiologic studies. One conclusion is that thyroid disease should be borne in mind when patients present with unexplained urinary frequency or retention.

Compensated 131I-therapy of solitary autonomous thyroid nodules: effect on thyroid size and early hypothyroidism

Thyroid function and thyroid gland volume, ultrasonically determined, were investigated in 27 hyperthyroid patients with solitary autonomous thyroid nodules before and during one year after 131I-treatment. Total thyroid volume decreased gradually from 40.9 +/- 3.5 ml (mean +/- SEM) before treatment to 23.9 +/- 1.8 ml (P less than 0.001) at 3 months after 131I-treatment. No further change was observed. All but two patients received only one dose of 131I, and in spite of a significant decrease also of the non-adenoma side of the gland, none became hypothyroid. We conclude that 131I-therapy has an important place in the treatment of solitary autonomous thyroid nodules since all our patients became euthyroid within 3 months, only 2 of 27 patients needed more than one dose of 131I, no cases of hypothyroidism occurred, and thyroid volume was substantially decreased.

Intellectual impairment after hyperthyroidism

Electroencephalography (EEG) and neuropsychological tests empirically shown to be sensitive to diffuse cerebral damage were performed in 26 patients 10 years after successful treatment of hyperthyroidism and in a control group with non-toxic goitre. In the hyperthyroid state 81% had abnormal EEG before treatment, and 10 years after treatment 68% still had abnormal EEG compared with 41% in the control group (P less than 0.05). In 7 out of 11 neuropsychological tests the previously hyperthyroid patients showed significant impairment compared with the control group. Twenty-three per cent of the patients displayed marked to severe intellectual impairment, 31% moderate and 41% slight or no impairment compared with 0%, 31% and 69%, respectively, in the control group (P less than 0.05). Four patients had been granted disability pension on the basis of the intellectual dysfunction. Signs of intellectual impairment indicating irreversible brain dysfunction after thyrotoxicosis thus seem to be a frequent, although hitherto not generally recognized, finding.

Audiological and temporal bone findings in myxedema

Fifteen patients with confirmed myxedema at a median age of 48 years (range 32 to 60 years) were referred for audiological evaluation before and after treatment with levothyroxine. The median interval between the pretreatment and posttreatment investigations was 18 months (range 9 to 27 months). In addition, 13 patients at a median age of 78 years (range 64 to 95 years) were audiologically reexamined after long-standing levothyroxine treatment. The observation period upon treatment with levothyroxine was 40 months (range 32 to 46 months). No improvement in hearing sensitivity could be demonstrated either in the younger patients or in the elderly. When compared to an age- and sex-matched unscreened population, the myxedematous patients did not demonstrate any different degree of hearing loss. Histological investigation of the temporal bones from an 83-year-old woman with myxedema, however, showed no morphological changes or deposition of glycosaminoglycans, changes which are compatible with true age-related hearing loss. It is concluded that no association exists between myxedema and hearing impairment and that no morphological or structural changes due to myxedema can be demonstrated in the temporal bones.

Increased frequency of goitre in epileptic patients on long-term phenytoin or carbamazepine treatment

Thyroid function, the clinical occurrence of goitre and ultrasonically determined thyroid gland volume were investigated in 23 patients with phenytoin- and 28 patients with carbamazepine-treated convulsive disorders and compared with matched healthy controls. In the phenytoin treated group median thyroid volume was 26 ml (range 14-57 ml) compared to 17 ml (range 8-41 ml) in the controls (P less than 0.01). Ten patients and four controls had a goitre (NS). Median serum T4 and FT4I levels were reduced, serum TSH level increased and serum T3, T3RU, FT3I and thyroglobulin levels unaltered compared with the controls. In the carbamazepine treated group median thyroid volume was 25 ml (range 13-66 ml) compared to 16 ml (range 9-44 ml) in the controls (P less than 0.01). Thirteen patients and three controls had a goitre (P less than 0.02). Median serum T4, FT4I and FT3I levels were reduced, serum thyroglobulin increased and serum T3, T3RU and TSH levels unaltered compared with the controls. The increase in thyroid size is probably a compensatory mechanism due to the low free thyroid hormones in serum caused by an increased hepatic degradation of thyroid hormones by phenytoin and carbamazepine.