title: Exogenous thyrotropin improves renal function in euthyroid patients, while serum creatinine levels are increased in hypothyroidism.
abstract: BACKGROUND
  There is evidence showing that the hypothyroid state results in increased serum creatinine levels. However, whether this is only due to the peripheral thyroid hormones or if thyroid-stimulating hormone (TSH) is also involved is not known.
  
  
  METHODS
  Serum creatinine levels and estimated glomerular filtration rate (eGFR) were assessed in thyroidectomized patients with varying thyroid hormones and TSH levels. Blood samples from Group 1 (21 patients) were obtained 1 month after complete thyroidectomy, while under a hypothyroid state (t1) and a sufficient time after thyroid hormones initiation (euthyroid state, t2). Group 2 (20 euthyroid patients) were sampled after recombinant human thyrotropin injections (rhTSH, t1) and later after rhTSH extinction (t2).
  
  
  RESULTS
  In Group 1, serum creatinine levels decreased after correction of hypothyroidism (85.3 ± 4.3 versus 78.0 ± 3.9 µmol/L; P = 0.04). In Group 2, serum creatinine levels increased after rhTSH withdrawal (70.6 ± 5.7 µmol/L versus 76.5 ± 5.8 µmol/L; P = 0.007). Between t1 and t2, eGFR varied accordingly [Group 1, 71.7 ± 3.5 versus 81.2 ± 4.5 mL/min/1.73 m² (P = 0.02); Group 2, 97.7 ± 7.4 versus 87.5 ± 5.9 (P = 0.007)]. The changes in TSH and eGFR following supplementation with thyroxine were significantly correlated (r = -0.6, P = 0.0041).
  
  
  CONCLUSIONS
  Iatrogenic hypothyroidism significantly increases serum creatinine and reversibly impairs eGFR, while treatment with rhTSH enhances renal function in euthyroid patients, supporting the existence of an influence of TSH level on renal function. The mechanisms by which peripheral thyroid hormones and TSH influence GFR need to be identified in physiology-orientated studies.
authors.affiliation: SAS RD - Néphrologie, Montpellier , France.
authors.forename: Flore
authors.initials: F
authors.lastname: Duranton
authors.affiliation: Service de Néphrologie, Dialyse et Transplantation, Hôpital Lapeyronie, Université de Montpellier, Montpellier , France.
authors.forename: Anouchka
authors.initials: A
authors.lastname: Lacoste
authors.affiliation: Institut Régional du Cancer (ICM) , Montpellier , France.
authors.forename: Patrick
authors.initials: P
authors.lastname: Faurous
authors.affiliation: Institut Régional du Cancer (ICM) , Montpellier , France.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Deshayes
authors.affiliation: Service de Médecine Interne , Hôpital Lapeyronie, Université de Montpellier, Montpellier , France.
authors.forename: Jean
authors.initials: J
authors.lastname: Ribstein
authors.affiliation: Service de Nutrition-Diabète, Hôpital Lapeyronie, Université de Montpellier, Montpellier , France.
authors.forename: Antoine
authors.initials: A
authors.lastname: Avignon
authors.affiliation: Service de Néphrologie, Dialyse et Transplantation, Hôpital Lapeyronie, Université de Montpellier, Montpellier , France.
authors.forename: Georges
authors.initials: G
authors.lastname: Mourad
authors.affiliation: SAS RD - Néphrologie, Montpellier , France ; Service de Néphrologie, Dialyse et Transplantation, Hôpital Lapeyronie, Université de Montpellier, Montpellier , France ; Néphrologie Dialyse St Guilhem, Sète , France.
authors.forename: Àngel
authors.initials: À
authors.lastname: Argilés
keywords: Creatinine; Glomerular Filtration Rate; Hypothyroidism; Thyrotropin; Thyroxine