Abstract
Serum free thyroxine (FT4) and free triiodothyronine (FT3) concentrations were measured in a group of 52 patients with subclinical hypothyroidism (SH) and in an equal group of age and sex-matched normal controls. SH was defined by normal total T4 (TT4) and total T3 (TT3) concentrations, normal FT4 and FT3 indices, raised TSH levels, in the absence of signs and symptoms of hypothyroidism. Serum FT4 levels averaged 6.1 ± 1.6 pg/ml (mean ± SD, p < 0.001 vs controls), with values below lower normal limits in 33/52 patients; mean FT3 concentrations averaged 3.1 ± 0.7 pg/ml (p < 0.001 vs controls), with values below lower normal limits in 8/52 patients. The analysis of results by the Galen and Gambino predictive value model demonstrated a higher sensitivity, but a lower specificity of FT4 as compared to FT3 in the diagnosis of SH. These results indicate that FT4 should be measured in addition to TSH for the diagnosis of impending thyroid failure, thus showing that in many cases patients with so-called subclinical hypothyroidism are actually already mild hypothyroid.
Similar content being viewed by others
References
Evered D.C., Ormston B.J., Smith P.A., Hall R., Bird T. Grades of hypothyroidism. Br. Med. J. 1: 657, 1973.
Ingbar S.H. The thyroid gland. In: Wilson J.D., Foster D.W. (Eds.), Textbook of Endocrinology. Saunders Co., Philadelphia, 1985, p. 682.
Tunbridge W.M.G., Brewis M., French J.M., Appleton D., Bird T., Clark F., Evered D.C., Grimley Evans J., Hall R., Smith P., Stephenson J., Young E. Natural history of autoimmune thyroiditis. Br. Med. J. 1: 258, 1981.
Ridgway E.C., Cooper D.S., Walker H., Rodbard D., Maloof F. Peripheral responses to thyroid hormones before and after L-thyroxine therapy in patients with subclinical hypothyroidism. J. Clin. Endocrinol. Metab. 53: 1238, 1981.
Bastenie P.A., Golstein J., Vanhaelst L., Smets P., Keys A., Karvonen M.J., Pursar S. Asymptomatic autoimmune thyroiditis and coronary heart disease. Lancet 2: 155, 1977.
Staub J.J., Noelpp B., Grani R., Gemsenjager E., Hauenstein M., Girard J. The relationship of serum thyrotropin (TSH) to the thyroid hormones after oral TSH-releasing hormone in patients with preclinical hypothyroidism. J. Clin. Endocrinol. Metab. 56: 1449, 1983.
Franklyn J.A., Sheppard M.C., Ramsden D.B., Hoffenberg R. Measurement of free thyroxine and free triiodothyronine in asymptomatic subjects with high concentrations of serum TSH and a history of radioiodine therapy. Clin. Endocrinol. (Oxf.) 20: 527, 1984.
Romelli P.B., Pennisi F., Vancheri L. Measurement of free thyroid hormones in serum by column adsorption chromatography and radioimmunoassay. J. Endocrinol. Invest. 2: 25, 1979.
Galen R.S., Gambino S.L. Beyond normality: the predictive value and efficiency of medical diagnoses. John Wiley & Sons, New York, 1980.
Pinchera A., Martino E., Bartalena L., Aghini-Lombardi F., Bambini G. Radioimmunoassay utilization in the assessment of thyroid function. In: Albertini A., Ekins R.P., Galen R.S. (Eds.), Cost/Benefit and Predictive Value of Radioimmunoassay. Elsevier Science Publishers, Amsterdam, 1984, p. 151.
Martino E., Pacchiarotti A., Aghini-Lombardi F., Grasso L., Bambini G., Baschieri L., Pinchera A. Serum free thyroxine in patients with T3-toxicosis. Acta Endocrinol. (Kbh.) 110: 354, 1985.
Wartofsky L., Burman K.D. Alteration in thyroid function in patients with systemic illness: the “euthyroid sick syndrome”. Endocr. Rev. 3: 164, 1982.
Larsen P.R. Thyroid-pituitary interaction. Feedback regulation of thyrotropin secretion by thyroid hormones. N. Engl. J. Med. 306: 23, 1982.
Patel Y.C., Pharoah P.O.D., Hornabrook R.W., Hetzel B.S. Serum triiodothyronine, thyroxine and thyroid-stimulating hormone in endemic goiter: a comparison of goitrous and nongoitrous subjects in New Guinea. J. Clin. Endocrinol. Metab. 37: 783, 1973.
Fenzi G.F., Ceccarelli C., Macchia E., Monzani F., Bartalena L., Giani C., Ceccarelli P., Lippi F., Baschieri L., Pinchera A. Reciprocal changes of serum thyroglobulin and TSH in residents of a moderate endemic goitre area. Clin. Endocrinol. (Oxf.) 23: 115, 1985.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Pacchiarotti, A., Martino, E., Bartalena, L. et al. Serum free thyroid hormones in subclinical hypothyroidism. J Endocrinol Invest 9, 315–319 (1986). https://doi.org/10.1007/BF03346934
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/BF03346934