Effect of therapy on the serum thyroglobulin concentration in patients with toxic diffuse goiter, toxic nodular goiter and toxic adenoma.

Serum thyroglobulin (S-Tg) was measured in 104 patients with thyrotoxicosis, 59 of whom had toxic diffuse goiter (Graves' disease), in 30 with toxic nodular goiter and in 15 with toxic adenoma. Before treatment, most patients had increased S-Tg concentrations, regardless of what type of thyrotoxicosis they had. After therapy the course of the S-Tg varied, two major patterns being observed: the S-Tg concentration increased in some patients but decreased in others, although no relationship could be found between these patterns and the outcome of therapy, the presence or absence of thyroglobulin antibodies (Tg-ab) or changes in the Tg-ab titer. However, the median pretreatment concentrations of S-Tg were significantly higher in patients with toxic nodular goiter and toxic adenoma than in those with toxic diffuse goiter (p less than 0.001 and p less than 0.05, respectively), but did not differ significantly between patients with toxic nodular goiter and toxic adenoma. The lowest posttreatment S-Tg concentrations were found after surgery, irrespective of type of thyrotoxicosis. The median pretreatment and posttreatment S-Tg concentrations in patients with toxic diffuse goiter who relapsed, did not differ from those patients in remission. This was also true of patients with toxic nodular goiter. In both groups, however, there was a tendency towards higher pretreatment S-Tg values in patients who subsequently relapsed. Serial determinations of S-Tg, on the other hand, are of limited value in predicting the risk of recurrence, independent of which type of thyrotoxicosis is involved.

Urinary C-peptide excretion at onset of insulin dependent diabetes mellitus in children.

The 24-hour urinary excretion of C-peptide and the plasma C-peptide concentration were measured at the onset of insulin dependent diabetes mellitus (IDDM) in children. The excretion of C-peptide was twice as high as that found in normal control subjects, whereas the plasma C-peptide values were markedly lower, indicating increased urinary leakage of C-peptide in this phase of the disease. In the diabetic children under seven years of age the mean value of C-peptide excretion was clearly lower than in the older children.

Evaluation of the usefulness of a sensitive immunoradiometric assay for thyroid stimulating hormone as a first-line thyroid function test in an unselected patient population.

A new sensitive immunoradiometric assay for serum thyroid stimulating hormone (TSH) was applied to 1627 consecutive patients from four large clinics at Malmö General Hospital, in whom a thyroid function disorder was suspected. The final diagnoses were taken from the patients' charts at a follow-up 1-2 years after the primary evaluation. If only those patients without thyroid disease were used as a reference population, the 5th percentile was 0.8 mIU/l. When this cutoff limit was applied to the unselected patient population, the TSH assay had a high sensitivity for the diagnosis of hyperthyroidism (96%), a lower specificity (64%) and a very low predictive value (10%). Therefore, in the majority of the patients (72%) the sensitive TSH assay cannot be used alone to define thyroid function.

Insulin sensitivity in the initial phase of type 1 diabetes mellitus.

The blood glucose response to a brief infusion of insulin (0.012 U/kg body wt) was studied in the initial phase of Type 1 diabetes in 21 children and in 20 healthy controls. The insulin effect was impaired in most of the diabetics and the mean blood glucose decrement was 14.3 +/- 3.5% (SEM) as compared with 20.9 +/- 2.1% in the normals. Subgrouping the diabetics according to the severity of the diabetic condition revealed normal (or even supranormal) sensitivity in the diabetics with mild metabolic derangement (mean blood glucose decrement 36.2 +/- 6.0%). In children with more disturbed metabolism mean blood glucose decrement was only 5.6 +/- 0.8% indicating a marked insulin resistance. Further evidence for a relationship between the insulin sensitivity and the severity of the diabetic state was found in the correlation between the percentual blood glucose decrement and the fasting blood glucose (r = -0.79, p less than 0.01), the glucose assimilation rate (r = 0.71, p less than 0.01), as well as the blood glucose level at 120 min during the OGTT (r = -0.76, p less than 0.01). Four of the insulin-resistant patients were re-tested during remission and exhibited then normal insulin sensitivity.

A prospective critical evaluation of in vitro thyroid function tests.

A number of 2 325 serum samples from a population of in- and outpatients were collected during a six-month period in order to evaluate the usefulness of various thyroid function tests in the clinical laboratory routine. The samples were analysed with the following thyroid function tests: total triiodothyronine (T3) (TT3), total thyroxine (T4) (TT4), free T3 index (FT3I), free T4 index (FT4I) and thyrotropin (TSH). One to two years after the primary evaluation, a follow-up was performed and the final diagnoses were checked in the patients' records. The values of these parameters in the diagnosis of hyperthyroidism were: FT3I greater than FT4I greater than TT3 greater than TT4. The corresponding results in the diagnosis of hypothyroidism were: TSH greater than FT4I greater than FT3I = TT3. No single test could detect both hyper- and hypothyroidism effectively. The only one-step strategy for thyroid evaluation in patients without apparent clinical signs of hyper- or hypothyroidism would therefore be the combined determination of T3 and TSH. The study also showed distinct differences between the reference values of the healthy population and patients without thyroid disorders.

A high prevalence of thyroglobulin autoantibodies in adults with and without thyroid disease as measured with a sensitive solid-phase immunosorbent radioassay.

Sera from 228 patients with thyroid disease and 140 healthy subjects without clinical or biochemical evidence of thyroid disease, were tested using a sensitive solid-phase immunosorbent radioassay (RIA) and a passive hemagglutination test (TRC test) for thyroglobulin antibodies (Tg-ab). With the RIA technique, Tg-ab was found in 27% of the controls (36% of the women and 15% of the men), whereas only 0.7% of them were Tg-ab positive with the TRC test. All individuals with primary hypothyroidism were Tg-ab positive with the RIA, compared with only 56% with the TRC test. Tg-ab (RIA) were found in 43/53 (81%) of the patients with toxic diffuse goiter, and in 30-40% of the patients with toxic nodular goiter, toxic adenoma, atoxic goiter, and thyroid carcinoma, the TRC test being positive in 10-17% of these patients. The high prevalence of Tg-ab in the healthy population suggests that subclinical thyroiditis is more frequent than has been assumed from antibody measurements made with less sensitive methods, and is in agreement with the prevalences reported from autopsy studies.

The influence of erythrocyte age on estimations of erythrocyte insulin binding in healthy children and adults and in conditions with increased erythropoiesis.

Insulin binding to erythrocytes was shown to lack any relationship to age-related factors of the erythrocyte such as the pyruvate kinase activity and the reticulocyte count in individuals with a normal erythropoiesis. After density separation of the erythrocytes in both normal adults and children and in individuals with increased erythropoiesis, a correlation to age-factors was evident (pyruvate kinase activity/insulin binding r = 0.59, p less than 0.01, reticulocyte count/insulin binding r = 0.44, p less than 0.01). An estimate of the components of variation in the binding showed that the unexplained variance is 60%. In the density separated samples the insulin binding correlated closer to the pyruvate kinase activity than to the number of reticulocytes. During treatment of haematopoietic diseases in the 4 patients with increased erythropoiesis, the disappearance rate for the reticulocyte count was much faster (T 1/2 = 9 days) than that of the insulin binding to erythrocytes (T 1/2 = 37 days) and that of pyruvate kinase activity (T 1/2 = 36 days). In one patient studied after splenectomy, the decrease in insulin binding paralleled the disappearance curve for 51Cr-tagged erythrocytes. These results suggest that insulin binds to erythrocytes, not only during the reticulocyte stage, but throughout their life span, though the binding, which is very closely related to their pyruvate kinase activity, steadily declines as the erythrocytes age.

Insulin binding to erythrocytes in children with type I diabetes mellitus before, and after insulin treatment.

125I-insulin binding to erythrocytes was studied in 24 children with type I diabetes mellitus before institution of insulin therapy, and in 10 normals. Mean specific 125I-insulin binding in the diabetics was significantly lower than in the controls (10.2 +/- 0.4% (SEM), as against 11.6 +/- 0.5%, P less than 0.05). In 8 diabetics the study was repeated after 3-6 weeks of therapy, at which time the insulin binding had increased to normal (12.1%, range 10.7-13.6). No correlation was found between insulin binding and blood glucose, plasma insulin or plasma beta-hydroxybutyrate. We conclude that insulin binding to the receptors is altered in the early phase of type I diabetes.

Purification and storage of thyroglobulin. Two important factors influencing the radioimmunoassay for thyroglobulin.

The effect upon the assay of the quality of the thyroglobulin (Tg) used as standard and tracer was evaluated by comparison of two preparations, one purified with protease inhibitors added (Tg-PI) and the other without (Tg-O). Tg-PI proved more stable than Tg-O. After freezing in phosphate-buffered saline almost all 125I-Tg-O was found to have dissociated into 12 S Tg, while only about half the 125I-Tg-PI had done so. Storage in glycerol, 500 g/l, at -20 degrees C or freezing in goat serum improved the quality of the 125I-Tg markedly, but Tg-PI still remained more stable than Tg-O. In addition, the two antisera tested gave different results in the radioimmunoassay with Tg-PI and Tg-O. With one antiserum a gradual loss of Tg immunoreactivity occurred parallel to the dissociation of Tg, while no such effect was noted with the other antiserum. This difference is believed to depend on varying proportions of conformational antibodies in the antisera, the binding sites for the conformational antibodies being distorted by the dissociation of the Tg molecule, while the binding sites for the sequential antibodies remain intact.

A new sensitive immunosorbent radioassay for the detection of circulating antibodies to polypeptide hormones and proteins.

A solid-phase immunosorbent radioassay for the detection of circulating antibodies to protein hormones is described. The assay is based on the binding of the homologous 125I-labelled antigen to the antibodies which are then bound to anti-IgG antibodies covalently coupled to Sepharose. It can easily be applied as a complement to any radioimmunoassay for the detection of circulating antibodies to the ligand measured. The assay system avoids falsely elevated values due to interference of high serum concentrations of the antigen. The assay was applied to measure antibodies to FSH, LH, TSH, GH, prolactin, insulin and thyroglobulin (Tg). Among patients with chronic thyroiditis Tg antibodies were found in 100% of the sera. In diffuse toxic goitre 73% of the patients had detectable Tg antibodies. Insulin antibodies were present in 82% of the sera from patients with insulin treated diabetes. No antibodies were found against the other protein hormones tested.

Combination of solid-phase second antibody and internal sample attenuator counting techniques. Radioimmunoassay of thyroid-stimulating hormone.

A method is described for the quantitation of free and bound antigen in a new radioimmunoassay which does not require centrifugation or decantation steps. The method involves coupling a second antibody to agarose spheres which also contain entrapped crystals of bismuth oxide (Bi2O3) in order to attenuate the gamma-radiation from the bound fraction of the 125I-labelled antigen. The system is designed so that the samples may be measured in a gamma counter 15 min after the spheres have been added. This new method was compared to a conventional radioimmunoassay for the analysis of the thyroid-stimulating hormone (TSH). Data were obtained with the modified radioimmunoassay which showed both high sensitivity and precision and also had a good correlation (r = 0.951) with data obtained using a conventional method.

The influence of danazol on pituitary function and on the ovarian follicular hormone secretion in premenopausal women.

The purpose of this investigation was to study the influence of danazol on the basal levels of luteinizing hormone (LH) and follicle-stimulating hormone (FSH), on their response to gonadotropin-releasing hormone (GnRH), as well as the effect of different doses on the serum levels of prolactin, estradiol and progesterone. Three groups of regularly menstruating women were treated with danazol, 600, 400 and 200 mg a day, respectively. Serum samples were obtained--and in the 600 mg group a GnRH-test was performed--before, and after one, 3 and 6 months of continuous medication. LH, FSH, prolactin, estradiol and progesterone were measured by radio-immunoassay. Compared with pretreatment levels in the early follicular phase, basal serum levels of gonadotropins were unchanged during treatment with danazol 600 mg. However, compared with pretreatment levels later on in the menstrual cycle, a slight but significant decrease in LH and increase in FSH were observed. The pituitary responsiveness to GnRH was significantly higher during danazol treatment, than found during the early follicular phase. Serum prolactin levels decreased significantly during treatment with 600 and 400 mg a day, but not with 200 mg a day. The mean estradiol levels on danazol 600 mg a day varied between 153 +/- 9 (SE) and 161 +/- 17 pmol/l, corresponding to the levels in the early follicular phase (100-250 pmol/l). In the lower dose groups, the mean estradiol levels were significantly higher, varying between 265 +/- 30 and 321 +/- 57 pmol/l in the 400 mg group, and between 279 +/- 39 and 405 +/- 125 pmol/l in the 200 mg group.(ABSTRACT TRUNCATED AT 250 WORDS)

Serum thyroglobulin in differentiated thyroid carcinoma.

Serum thyroglobulin (S-Tg) concentrations were measured in 262 patients with differentiated thyroid carcinoma. Analysis of S-Tg with respect to histology showed that the follicular variety of carcinoma had the highest S-Tg values preoperatively and postoperatively when metastases were found. The S-Tg levels during thyroxine treatment accurately predicted the results of 131-I total body scan in all but two cases. In another patient both S-Tg and total body iodine scan were negative at the time when metastases were discovered at X-ray examination. All but two patients with negative scan had S-Tg less than 10 micrograms/l, whereas patients with metastases had values between 11 and greater than 5000 micrograms/l. In patients with residual thyroid bed uptake the S-Tg range was from less than 2 to 84 micrograms/l. The authors conclude that determination of the S-Tg level can replace total body iodine scan in most patients who have undergone ablative therapy for differentiated thyroid carcinoma.

Methods of reducing the effect of spontaneous dissociation of antigen-antibody interactions in radioimmunoassays with special reference to internal sample attenuator counting (ISAC).

A time dependent decrease of sample counts was observed in an adsorption radioimmunoassay with internal sample attenuator counting. The drift caused a bias in the estimate of the amount of antigen in the samples. The size of this deviation was dependent upon the length of time after the calibration curve was made that the samples were measured. This was essentially due to dissociation of the antigen-antibody complexes as the adsorber can act as a second receptor to the antigen. Addition of slowly sedimenting starch microspheres or starch particles inhibited the drift by forming a diffusion barrier on the attenuating pellet.

Radioimmunoassay of delta sleep-inducing peptide using an iodinated p-hydroxyphenylpropionic acid derivative as tracer.

A highly sensitive radioimmunoassay for delta sleep-inducing peptide (DSIP) has been developed. A p-hydroxyphenylpropionic acid conjugate of DSIP was used for radioiodination. Using reversed-phase high performance liquid chromatography the labelled DSIP derivative was isolated in a high yield and with a high specific activity. The assay allows measurement of DSIP-like material in body fluids with a minimum detectable concentration of 0.1 ng/ml standard DSIP (10 pg/tube).

Erythrocyte insulin receptors and insulin sensitivity in adrenocortical insufficiency. Report of a case of diabetes mellitus type I with superimposed Addison's disease.

Studies on erythrocyte insulin receptors were performed in a boy with type I diabetes mellitus and superimposed adrenocortical insufficiency before and during treatment with hydrocortisone and 9-alpha-fluorohydrocortisone. The development of the adrenal insufficiency was associated with a progressively increased sensitivity to insulin which reverted after therapy. The maximum specific insulin binding of the erythrocytes was low during threatening addisonian crisis (6.9%) but normalized during hydrocortisone treatment (12.0%). These findings suggest that the increased insulin sensitivity characteristic for adrenocortical insufficiency is not an effect of an increased insulin receptor concentration and that hypocortisolaemia is associated with a down-regulation of the insulin receptors.

Radioimmunoassay of pro-gamma-melanotropin, the amino-terminal fragment of proopiolipomelanocortin.

A RIA has been developed for natural porcine pro-gamma MSH, the 103-amino acid peptide that represents the amino-terminal part of proopiolipomelanocortin. Rabbits were immunized with the purified peptide polymerized with glutaraldehyde. The antiserum is directed against the amino-terminal end of the antigen and does not cross-react with corticotropin, beta-lipotropin, beta-endorphin, gamma 3MSH, or gamma 2MSH. The minimum detectable concentration is 0.15 ng/ml standard pro-gamma MSH (15 pg/tube). Pro-gamma MSH-like immunoreactivity was detected in plasma and extracts of the hypothalamus and pituitary of pigs. Gel chromatography of these extracts revealed at least three immunoreactive peaks in the anterior and neurointermediate lobes of the pituitary, whereas two immunoreactive peaks were found in extracts of the hypothalamus.

Single photon tomographic imaging of a standard heart phantom with 201T1: a gamma camera based system.

A standard heart phantom (University of Iowa design), including discrete myocardial walls, a central blood pool, and a 24-cc transmural "cold" defect, was studied with both planar and transverse tomographic imaging. The heart phantom was filled with 201T1 and placed within a cylindrical tank containing water and 201T1 to simulate nonmyocardial background activity from the thorax. The tomographic imaging system used was a commercially available, rotating, large field-of-view gamma camera. Image reconstruction from 64 sampling angles was performed in a nuclear medicine minicomputer system. The percentage activity in the region of the defect (actual activity of 0) contrasted to the normal wall was compared between planar and 1.25-cm transaxial tomographic slices. Defect activity fell to between 65% and 85% of that of the opposing normal wall in planar images, whereas it fell to between 26% and 49% of that of the normal wall in the tomographic images. In most cases, tomographic defect activity was half or less than that in the planar image. The geographic extent of the defect was seen in an appropriate number of tomographic slices; i.e., the geographic 3.2-cm defect length was predominantly seen in three 1.25-cm transverse slices. We conclude that camera-based tomographic systems show promise for improved 201T1 myocardial defect detection and quantitation over conventional planar images.

Internal sample attenuator counting (ISAC). A new technique for separating and measuring bound and free activity in radioimmunoassays.

I describe a new method for the separation and counting of bound and free activity in radioimmunoassays. Particles containing a radiation-absorbing (attenuating) material are added to the assay. They shield the radiation from either the antibody-bound or the free radioligand. This obviates such manipulations conventionally involved in the separation and counting steps of radioimmunoassays as centrifugation and decanting. Bismuth oxide is used as the attenuator. Particles with different properties are described. In one type, bismuth oxide is combined with active charcoal in an agarose matrix and serves as an adsorbant for the free radioligand. In another type bismuth oxide is trapped within a polyacrylamide matrix to which antibodies are coupled. This particle can be used with a first- or a second-antibody bound activity. Application of the technique is illustrated with radioimmunoassays for thyroxin, triiodothyronine, human choriogonadotropin, and lutropin (luteinizing hormone).