Growth hormone (GH) treatment reduces peripheral thyroid hormone action in girls with Turner syndrome

• Published in: Clinical endocrinology (Oxford) Vol. 67; no. 4; pp. 629 - 636
• Main Authors: Susperreguy, S., Miras, M. B., Montesinos, M. M., Mascanfroni, I. D., Muñoz, L., Sobrero, G., Silvano, L., Masini-Repiso, A. M., Coleoni, A. H., Targovnik, H. M., Pellizas, C. G.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.10.2007; Blackwell
• Subjects: Actins - genetics; Analysis of Variance; Biological and medical sciences; Biomarkers - blood; Case-Control Studies; Child; Collagen - blood; Depression, Chemical; Endocrinopathies; Female; Follow-Up Studies; Fundamental and applied biological sciences. Psychology; Growth Hormone - therapeutic use; Gynecology. Andrology. Obstetrics; Humans; Insulin-Like Growth Factor I - analysis; Male and female genital diseases. Gonadal dysgenesis. Hermaphroditism. Sex hormones resistance; Medical sciences; Osteocalcin - blood; Peptide Fragments - blood; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - analysis; Sex Hormone-Binding Globulin - analysis; Thyroid Hormone Receptors alpha - genetics; Thyroid Hormone Receptors beta - genetics; Thyroid Hormones - blood; Thyrotropin - blood; Triiodothyronine - blood; Turner Syndrome - blood; Turner Syndrome - drug therapy; Vertebrates: endocrinology; Chromosomal aberration; Human; Dysgenesia; Hormone therapy; Genital system; Somatotropin hormone; Sexual differentiation disorder; Turner syndrome; Female genital diseases; Adenohypophyseal hormone; Malformation; Gonad; Female; Thyroid hormone; Child; Endocrinology
• ISSN: 0300-0664; 1365-2265
• DOI: 10.1111/j.1365-2265.2007.02936.x

Summary Objective  Turner syndrome (TS) is an indication for GH therapy in spite of the modest growth response. Somatic growth depends not only on GH insulin‐like growth factor I (IGF‐I) axis but also on thyroid hormone (TH) status. We have previously reported that supraphysiological IGF‐I levels diminished TH actions in rat tissues by reducing the nuclear TH receptor (TR). GH treatment to TS patients induces high IGF‐I levels and therefore a reduction of TH action in tissues may be expected. We aimed at evaluating the effect of GH therapy in TS girls on peripheral TH action. Design and patients  We set up a reverse transcription‐polymerase chain reaction (RT‐PCR) for TR mRNA estimation in peripheral blood mononuclear cells (PBMC) and compared TR mRNA levels from 10 normal, 10 TS and 10 TS girls under GH therapy (0·33 mg/kg/week for 0·5–2 years). Measurements  After RNA extraction from PBMC, TR and β‐actin mRNAs were coamplified by RT‐PCR. In addition serum biochemical markers of TH action were measured: thyrotropin (TSH), sex hormone binding globulin (SHBG), osteocalcin (OC), β‐crosslaps (β‐CL), iodothyronines by electrochemiluminescency and IGF‐I by immunoradiometric assay (IRMA) with extraction. Results  TR mRNAs from PBMC were reduced in TS patients under GH treatment. In turn, serum TSH, OC, β‐CL and IGF‐I were increased while SHBG was reduced by GH treatment in TS patients. Conclusions  GH treatment reduced TR expression in PBMC and biochemical serum markers of TH action. These results suggest that GH treatment in TS patients impair peripheral TH action at tissue level and prompt a role in the reduced growth response to the therapy.