Impact of the serum thyroglobulin concentration on the diagnosis of benignand malignant thyroid diseases

Aim of this study is to evaluate new and controversially discussed indicati ons for determining the thyroglobulin (Tg) level in different thyroid disea ses to support routine diagnostics. Methods: The following groups were incl uded: 250 healthy subjects without goiter, 50 persons with diffuse goiter, 161 patients with multinodulor goiter devoid of functional disorder (108 of them underwent surgery, in 17 cases carcinomas were detected), 60 hyperthy roid patients with autonomously functioning nodular goiter, 150 patients wi th Hashimoto's thyroiditis and 30 hyperthyroid patients with Groves' diseas e. Results: The upper limit of the normal range of the Tg level was calcula ted as 30 ng Tg/ml. The evaluation of the collective with diffuse goiter sh owed that the figure of the Tg level con be expected in a similar magnitude as the thyroid volume in milliliters. Nodular tissue led to for higher Tg values then presumed when considering the respective thyroid volume, with a rather high variance. A formula for a rough prediction of the Tg levels in nodular goiters is described. In ten out of 17 cases with thyroid carcinom a, the Tg was lower than estimated with thyroid and nodular volumes, but tw o patients showed a Tg exceeding 1000 ng/ml. The collective with functional autonomy had a significantly higher overage Tg level than a matched euthyr oid group being under suppressive levothyroxine substitution. However, due to the high variance of the Tg values, the autonomy could not consistently be predicted with the Tg level in individual cases. The patients with Hashi moto's thyroiditis showed slightly decreased Tg levels. In Groves' disease, a significantly higher overage Tg level was observed compared with a match ed group with diffuse goiter, but 47% of all Tg valves were still in the no rmal range (< 30 ng/ml). Conclusion: Elevated Tg levels indicate a high pro bability of thyroid diseases, such as malignancy, autonomy or Groves' disea se. However, as low Tg concentrations cannot exclude the respective disorde r, a routine Tg determination seems not to be justified in benign thyroid d iseases.