In Reply

Hormone Replacement After Thyroid and Parathyroid Surgery by Prof. Dr. med. Andreas Schäffler in volume 47/2010

We thank Dr Otto for his remarks, which do not contradict our own recommendations. The TSH target ranges recommended by specialty societies for hormone replacement therapy for primary hypothyroidism cited the “lower standard value for TSH,” which can obviously be interpreted in various ways. Since all sources agree with regard to the upper threshold of 2.0 mU/L, the values vary only with regard to the lower limit by source (country, type of assay) from 0.5 mU/L (1) to 0.4 mU/L (2) and to 0.3 mU/L (3). There are no systematic data about which range is more appropriate within the lower threshold (0.5–1 mU/L or 1–2 mU/L). Rather, the factors mentioned by Dr Otto, which relate to the individual patient and are based on his or her individual situation, are important for the selected target range. In the article, 1–2 mU/L was recommended, since a primary target value of 0.5 mU/L entails a risk of subclinical hypothyroidism, which has been proved to be associated with complications including atrial fibrillation, osteoporosis, and diastolic cardiac dysfunction. If more than 6 ml of functional tissue remains this may be sufficient in some patients to maintain autochthonous euthyroidism. This residual tissue is susceptible to recurrent development of goiter, so iodine supplementation is a given in this setting (1). There is no reason to assume that, if additional L-thyroxine substitution is required (especially in patients at risk of iodine deficiency and in young patients), the residual tissue is not at all times, even for several decades, subject to recurrent goiter development. However, controlled data to refute or confirm this do not exist.

We thank Professor Goretzki and his colleagues for their correct additional points. Owing to reasons of space and the topical focus on hormone replacement therapy we were not able to discuss intraoperative surgical aspects, such as autotransplantation or cryopreservation. We cannot recommend treating every postoperative patient with hypoparathyroidism identically, with high doses of calcium and calcitriol, since hypercalcemia and overdosage of the Ca× phosphate product should be avoided and since individual patients respond to very different degrees. In such a scenario, close monitoring by the treating physician is recommended postoperatively.

We thank Hannemann, Nauck, and Wallaschofski for their comments, which we can only underline. For reasons of space we were not able to discuss the cited references any further.

DOI: 10.3238/arztebl.2011.0134b

Prof. Dr. med. Andreas Schäffler

Klinik und Poliklinik für Innere Medizin I

Universität Regensburg

93042 Regensburg, Germany

Conflict of interest statement
The authors of all contributionsr declare that no conflict of interest exists according to the guidelines of the International Committee of Medical Journal Editors.

References

1. DGE-Empfehlung, in: Gärtner, R., Reincke, M.: Internist, 2008; 49: 538–544.

2. Wiersinga WM: Thyroid hormone replacement therapy. Horm Res 2001; 56(Suppl 1): 74–81.

3. Cooper DS, Doherty GM, Haugen BR: Management guidelines for patients with thyroid nodules and differentiated thyroid cancer. Thyroid 2006; 16(2): 109–42.

4. Schäffler A: Hormone replacement after thyroid and parathyroid surgery. Dtsch Arztebl Int 2010; 107(47): 827–34.