Effect of Long-Term Administration of Cross-Sex Hormone Therapy on Serum and Urinary Uric Acid in Transsexual Persons

• Published in: The journal of clinical endocrinology and metabolism 2008-06, Vol.93 (6), p.2230-2233
• Main Authors: Yahyaoui, R., Esteva, I., Haro-Mora, J. J., Almaraz, M. C., Morcillo, S., Rojo-Martínez, G., Martínez, J., Gómez-Zumaquero, J. M., González, I., Hernando, V., Soriguer, F.
• Format: Article
• Language: English
• Subjects: Adult; Biological and medical sciences; Blood Glucose - analysis; Dose-Response Relationship, Drug; Endocrinopathies; Estradiol - blood; Feeding. Feeding behavior; Female; Follow-Up Studies; Fundamental and applied biological sciences. Psychology; Gonadal Steroid Hormones - administration & dosage; Gonadal Steroid Hormones - therapeutic use; Humans; Insulin - blood; Insulin Resistance; Male; Medical sciences; Time Factors; Transsexualism - blood; Transsexualism - drug therapy; Transsexualism - urine; Uric Acid - blood; Uric Acid - urine; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Vertebrates: endocrinology
• ISSN: 0021-972X; 1945-7197
• DOI: 10.1210/jc.2007-2467

Background: Transsexual persons afford a very suitable model to study the effect of sex steroids on uric acid metabolism. Design: This was a prospective study to evaluate the uric acid levels and fractional excretion of uric acid (FEUA) in a cohort of 69 healthy transsexual persons, 22 male-to-female transsexuals (MFTs) and 47 female-to-male transsexuals (FMTs). The subjects were studied at baseline and 1 and 2 yr after starting cross-sex hormone treatment. Results: The baseline levels of uric acid were higher in the MFT group. Compared with baseline, uric acid levels had fallen significantly after 1 yr of hormone therapy in the MFT group and had risen significantly in the FMT group. The baseline FEUA was greater in the FMT group. After 2 yr of cross-sex hormone therapy, the FEUA had increased in MFTs (P = 0.001) and fallen in FMTs (P = 0.004). In MFTs, the levels of uric acid at 2 yr were lower in those who had received higher doses of estrogens (P = 0.03), and the FEUA was higher (P = 0.04). The FEUA at 2 yr was associated with both the estrogen dose (P = 0.02) and the serum levels of estradiol-17β (P =0.03). In MFTs, a correlation was found after 2 yr of therapy between the homeostasis model assessment of insulin resistance and the serum uric acid (r = 0.59; P = 0.01). Conclusions: Serum levels of uric acid and the FEUA are altered in transsexuals as a result of cross-sex hormone therapy. The results concerning the MFT group support the hypothesis that the lower levels of uric acid in women are due to estrogen-induced increases in FEUA.