title: Isotopic renal function studies in severe hypothyroidism and after thyroid hormone replacement therapy.
abstract: OBJECTIVE
  To investigate the possible changes in the renal tubular function in severe short-term hypothyroidism using (99m)Tc-MAG(3) renography.
  
  
  METHODS
  27 consecutive thyroidectomized patients (7 males and 20 females) aged 19-79 (mean 53) years were included in the present study. (99m)Tc-MAG(3) renography was performed in all patients before and after thyroid hormone replacement therapy. In addition, (51)Cr-EDTA clearance and serum creatinine concentrations were determined.
  
  
  RESULTS
  The serum creatinine concentrations were significantly increased in hypothyroidism as compared with the concentrations after thyroxine substitution (1.30 +/- 0.44 vs. 1.04 +/- 0.32 mg/dl, p < 0.05). According to the (51)Cr-EDTA clearance, the glomerular filtration rate was significantly lower in hypothyroidism than after treatment (61 +/- 18 vs. 75 +/- 23 ml/min). In contrast, we did not find any significant change in the renographic parameters for (99m)Tc-MAG(3) before and after treatment (total excreted activity 20 min after administration 51 +/- 12 vs. 54 +/- 14%; T(max) left:right 4.2 +/- 1.77 : 3.91 +/- 1.06 min vs. 4.1 +/- 1.66 : 4.4 +/- 1.96 min).
  
  
  CONCLUSIONS
  We did not find any influence of thyroid hormones on the outcome of (99m )Tc-MAG(3) renography. As (99m)Tc-MAG(3) reflects the tubular function, it seems that the renal hemodynamic changes in severe hypothyroidism mainly affect the glomerular function. In general, the glomerular filtration rate reduction seems to be reversible after hormone substitution therapy; however, care has to be taken in patients with renal insufficiency.
authors.affiliation: Department of Nuclear Medicine, University of Vienna, Vienna, Austria. georg.karanikas@akh-wie.ac.at
authors.forename: Georgios
authors.initials: G
authors.lastname: Karanikas
authors.forename: Matthias
authors.initials: M
authors.lastname: Schütz
authors.forename: Monica
authors.initials: M
authors.lastname: Szabo
authors.forename: Alexander
authors.initials: A
authors.lastname: Becherer
authors.forename: Karoline
authors.initials: K
authors.lastname: Wiesner
authors.forename: Robert
authors.initials: R
authors.lastname: Dudczak
authors.forename: Kurt
authors.initials: K
authors.lastname: Kletter
mesh_terms: D000328:Adult; D000368:Aged; D003404:Creatinine / Q000097:blood; D004492:Edetic Acid; D005260:Female; D005919:Glomerular Filtration Rate / Q000187:drug effects; D020249:Hormone Replacement Therapy; D006801:Humans; D007037:Hypothyroidism / Q000188:drug therapy / Q000503:physiopathology*; D007668:Kidney / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011866:Radioisotope Renography; D019275:Radiopharmaceuticals; D017263:Technetium Tc 99m Mertiatide; D013965:Thyroidectomy; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood / Q000627:therapeutic use*; D016896:Treatment Outcome; D014284:Triiodothyronine / Q000097:blood
chemical_list: D019275:Radiopharmaceuticals; D014284:Triiodothyronine; D017263:Technetium Tc 99m Mertiatide; D013972:Thyrotropin; D004492:Edetic Acid; D003404:Creatinine; D013974:Thyroxine