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Measurements of serum thyroglobulin (hTg) were performed using a specific radioimmunoassay. Sera with detectable anti-thyroglobulin (anti-Tg) antibody titers (> or = 1:10) as assessed by passive hemagglutination were discarded. Assays were carried out under conditions in which anti-Tg titers less than 1:10 produced no interference. The assay sensitivity was 1.25 ng/ml and the mean +/- SE concentration of serum hTg in 58 control subjects was 9.5 +/- 0.9 ng/ml (range < 1.25-27 ng/ml). A slight but significant (p < 0.025) increase in the mean hTg level was observed in 12 pregnant women at delivery (25.7 +/- 5.2 ng/ml). Moderate to marked elevations of serum hTg were observed in patients with nontoxic goiter (61.4 +/- 15 ng/ml; n = 23), subacute thyroiditis (138 +/- 67 ng/ml; n = 5), toxic adenoma (129 +/- 47 ng/ml; n = 13), untreated (424 +/- 101 ng/ml; n = 35) or treated (328 +/- 222 ng/ml; n = 14) toxic diffuse goiter. 88 patients with thyroid carcinoma and 10 with nonthyroidal malignancies were studied. The mean level of serum hTg was increased in untreated differentiated thyroid carcinoma (89.5 +/- 19 ng/ml; n = 13) but not in undifferentiated (10 +/- 2.9 ng/ml; n = 6) or medullary (0.8 +/- 0.2 ng/ml; = 3) carcinoma. In treated differentiated thyroid carcinoma the mean hTg levels were normal (8.2 +/- 0.2 ng/ml) in patients (n = 24) with no evidence of either a thyroid residue or metastatic disease, moderately increased (56.6 +/- 16 ng/ml) in patients (n = 27) with residual thyroid tissue, markedly elevated in patients with lymph node metastases (199 +/- 50 ng/ml; n = 5) and extremely elevated in those with bone (4004 +/- 982 ng/ml; n = 8) or lung (2520 +/- 620 ng/ml; n = 5) metastases. There was no significant difference in serum hTg between functioning (n = 23) and nonfunctioning (n = 5) metastases as assessed by 131I whole body scan. A slight but significant (p < 0.0005) increase in the mean concentration of hTg was observed in nonthyroidal malignancies (21.7 +/- 4.5 ng/ml; n = 10). Serial measurements showed a transient increase of serum hTg after 131I therapy of differentiated thyroid carcinoma, toxic diffuse goiter or toxic adenoma, with peak values usually occurring within the first three days. A fall of serum hTg after administration of suppressive doses of thyroid hormone to patients with nontoxic goiter and a rise after discontinuation of thyroid suppressive therapy in patients with metastatic differentiated thyroid carcinoma was observed.(ABSTRACT TRUNCATED AT 400 WORDS)

It is now well accepted that serum thyroglobulin (Tg) determination is a specific marker of disease activity in well-differentiated thyroid cancer after total thyroidectomy. In this study we examined 15 thyroidectomized patients with metastases from medullary thyroid cancer and 10 patients with metastases from undifferentiated thyroid cancer, to determine whether serum Tg measurement could be useful also in these types of thyroid tumors. In contrast with differentiated thyroid cancer, which had high levels of circulating serum Tg, patients with medullary and undifferentiated thyroid cancer had undetectable or low levels of serum Tg. Thus, serum Tg measurements are not useful in the diagnosis of metastatic disease in these patients.

Serum thyroglobulin (Tg) was measured in the cord blood of 635 newborns and serum thyroxine (T4) reverse triiodothyronine (rT3), TSH and T3 were measured in about 200 of them. Cord Tg was detectable in all newborns with a mean +/- SE value (50 +/- 1.3 ng/ml) higher than that found in the serum of adult subjects (n = 144; Tg = 13 +/- 1.1; p less than 0.0001). Cord Tg had a log-normal distribution. A low, but positive correlation was found between cord Tg and cord TSH (n = 242; r = 0.17; p less than 0.05) but not with cord T4 or cord rT3. Gestational age was negatively correlated with cord Tg or cord rT3 (rS = 0.97; p less than 0.01; rS = -0.89; p less than 0.02, respectively) while was positively correlated with cord T4 or cord TSH (rS = 0.85; p less than 0.05; rS = 0.86; p less than 0.01, respectively). Birth weight, maternal diabetes, induction of labor with oxitocin, cesarian section and newborns' illness showed no influence on cord Tg levels when considered alone, but decreased cord Tg levels were found in ill newborns delivered by cesarian section. On the contrary, increased cord Tg levels were present in cord blood of newborns who developed hypoglycemia soon after birth and in small for gestational age newborns. In 24 newborns studied daily for the first 6 days of life, serum Tg was always detectable with mean values not different from those found in the cord blood.(ABSTRACT TRUNCATED AT 250 WORDS)

Measurements of circulating thyroglobulin (hTg) and 131I whole body scan were performed in 101 patients with differentiated thyroid carcinoma who had been subjected to surgical thyroidectomy and 131I ablation of remaining thyroid tissue. All 45 patients with positive scans (i.e. functioning metastases) had elevated hTg concentrations. Of fifty-six patients with negative scans forty-two had undetectable or very low hTg levels and were considered to be free of metastatic thyroid tissue, whereas fourteen showed the presence of non-functioning metastases in the clinical and/or radiological examination. In this group of patients, eleven had elevated serum hTg levels while the other three patients had detectable hTg concentrations within the normal range. These results indicate that serum hTg measurements correlate very well with scan findings and have the added advantage of detecting non-functioning metastases which would not be detected by scanning. We concluded that measurement of serum hTg may be used together with scanning, as the first step in the follow-up of thyroidectomized patients with differentiated thyroid carcinoma.

Subjects living in iodine deficient areas were reported to have elevated serum thyroglobulin (Tg) concentrations. This finding was interpreted as related to thyroid stimulation. Discrepant results, however, were found when serum Tg concentrations were correlated either with serum TSH or with goitre size. In this study we investigated the relationships between goitre size, serum Tg and serum TSH in 488 unselected adult subjects living in an endemic area of North-Western Tuscany (Garfagnana district). The control group comprised 352 subjects residing in a non-endemic area. In the endemic area a high prevalence of goitre was found (80.1%), thyroid enlargement being slight to moderate in the majority of cases and very large only in six subjects. Serum Tg concentrations increased and serum TSH levels decreased with the size of goitre. Statistical analysis by the chi-square cross correlation test showed that the converse changes of serum Tg and serum TSH in relation to goitre size were highly significant. These findings indicate that the increase of serum Tg occurring in endemic goitrous subjects may be related to factors other than TSH stimulation. Functional autonomy of the thyroid may account for the finding of low serum TSH and elevated serum Tg values in patients with large goitres. The present data do not exclude the possibility that the release of Tg is influenced by TSH stimulation, but indicate that other factors may be responsible for the increased levels of Tg found in endemic goitre.

The value of serum thyroglobulin (Tg) determination in the differential diagnosis of congenital hypothyroidism was assessed by serum Tg measurements in 14 patients with proven congenital hypothyroidism, in 3 subjects with transient perinatal hypothyroidism, in 3 newborns with congenital thyroxine binding globulin (TBG) deficiency and in 34 normal controls. Serum Tg was undetectable in all 6 cases with thyroid agenesis, normal or moderately elevated in the 4 cases with ectopic thyroid, markedly increased in the 4 cases with dyshormonogenic goiter and normal in the 3 cases with transient hypothyroidism and in the 3 with TBG deficiency. The present data indicate that serum Tg measurements may be useful in the differentiation of athyreotic hypothyroidism from other conditions of congenital hypothyroidism.

We investigated the usefulness and limits of serum thyroglobulin, serum calcitonin, and serum tissue polypeptide antigen as humoral markers for thyroid carcinoma in 364 patients with papillary, follicular, medullary, and undifferentiated types of thyroid cancer. In agreement with other studies we found that serum thyroglobulin was a specific and sensitive marker for well-differentiated thyroid cancer after total thyroidectomy. Lymph node, lung, and bone metastases were associated with high serum thyroglobulin concentrations, both during and after thyroid-suppressive therapy with L-thyroxine. Serum thyroglobulin determination was superior to whole body scanning in predicting the presence of differentiated metastases, because patients with nonfunctioning metastases and negative whole body scan also had high levels of serum thyroglobulin. Serum calcitonin levels were increased in all patients with active medullary thyroid cancer, confirming the specificity of this marker in detecting tumors arising from parafollicular C-cells. Furthermore, in medullary thyroid cancer serum tissue polypeptide antigen levels were also increased in most patients. This last substance was found to be increased also in undifferentiated thyroid cancer. Of particular interest was the finding of increased serum tissue polypeptide antigen levels in 15 cases of differentiated thyroid cancer, whose metastases underwent a progressive process of "dedifferentiation."