title: Renal function improves with the treatment of hypothyroidism.
abstract: BACKGROUND
  It has been known that thyroid hormones may affect renal function. In this study, we aimed to investigate the effect of levothyroxine replacement on renal function in hypothyroid patients before and after treatment.
  
  
  METHODS
  We retrospectively investigated free T3 (fT3), free T4 (fT4), TSH, creatinine, and eGFR measurements during both hypothyroid and euthyroid states of hypothyroid patients. The eGFR was calculated using the simplified Modification of Diet in Renal Disease formula.
  
  
  RESULTS
  fT3, fT4, and eGFR measurements increased, meanwhile creatinine and TSH levels decreased significantly after euthyroidism was achieved with levothyroxine treatment (p < 0.0001 for all). The correlation analyses revealed that ∆creatinine and ∆TSH levels were significantly correlated before and after levothyroxine treatment (r: 0.288, p < 0.0001). ∆eGFR and ∆TSH levels were significantly correlated before and after LT4 treatment (r: -0.272, p < 0.0001).
  
  
  CONCLUSIONS
  In this study, we evaluated creatinine and eGFR levels in patients with hypothyroidism and found out that renal function improved in most patients after euthyroidism was achieved. In some patients, above-normal creatinine levels completely returned to normal once the patients became euthyroid.
authors.affiliation: a Department of Internal Medicine , Kecioren Teaching and Research Hospital , Kecioren , Ankara , Turkey.
authors.forename: Oktay
authors.initials: O
authors.lastname: Bulur
authors.affiliation: a Department of Internal Medicine , Kecioren Teaching and Research Hospital , Kecioren , Ankara , Turkey.
authors.forename: Kursat
authors.initials: K
authors.lastname: Dal
authors.affiliation: b Department of Endocrinology and Metabolism , Kecioren Teaching and Research Hospital , Kecioren , Ankara , Turkey.
authors.forename: Derun Taner
authors.initials: DT
authors.lastname: Ertugrul
authors.affiliation: a Department of Internal Medicine , Kecioren Teaching and Research Hospital , Kecioren , Ankara , Turkey.
authors.forename: Murat
authors.initials: M
authors.lastname: Eser
authors.affiliation: a Department of Internal Medicine , Kecioren Teaching and Research Hospital , Kecioren , Ankara , Turkey.
authors.forename: Fatma
authors.initials: F
authors.lastname: Kaplan Efe
authors.affiliation: a Department of Internal Medicine , Kecioren Teaching and Research Hospital , Kecioren , Ankara , Turkey.
authors.forename: Serdar
authors.initials: S
authors.lastname: Karakaya
authors.affiliation: c Department of Rheumatology , Kecioren Teaching and Research Hospital , Kecioren , Ankara , Turkey.
authors.forename: Kubilay
authors.initials: K
authors.lastname: Şahin
authors.affiliation: a Department of Internal Medicine , Kecioren Teaching and Research Hospital , Kecioren , Ankara , Turkey.
authors.forename: Salih
authors.initials: S
authors.lastname: Baser
authors.affiliation: a Department of Internal Medicine , Kecioren Teaching and Research Hospital , Kecioren , Ankara , Turkey.
authors.forename: Naim
authors.initials: N
authors.lastname: Ata
authors.affiliation: d Department of Nephrology , Kecioren Teaching and Research , Kecioren , Ankara , Turkey ; Hospital.
authors.forename: Aysun
authors.initials: A
authors.lastname: Aybal Kutlugun
authors.affiliation: a Department of Internal Medicine , Kecioren Teaching and Research Hospital , Kecioren , Ankara , Turkey.
authors.forename: Esin
authors.initials: E
authors.lastname: Beyan
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003404:Creatinine / Q000652:urine*; D005260:Female; D005919:Glomerular Filtration Rate / Q000187:drug effects*; D006801:Humans; D007037:Hypothyroidism / Q000097:blood* / Q000188:drug therapy*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013974:Thyroxine / Q000008:administration & dosage / Q000494:pharmacology*; D055815:Young Adult
chemical_list: D003404:Creatinine; D013974:Thyroxine
keywords: creatinine; eGFR; hypothyroidism