title: Determining the enzymatic activities of iodothyronine 5'-deiodinases in renal medulla and cortex.
abstract: BACKGROUND
  Thyroid hormone disorders in patients with chronic kidney disease (CKD) are a result of impaired conversion of T4 to T3. The importance of kidneys in thyroid hormones conversion is not fully understood. The activities of different types of iodothyronine deiodinases in the kidney structures have not been determined yet. The aim of this study was to determine the activity of deiodinase type 1 (D1) and type 2 (D2) in renal cortex and medulla in renal cancer patients.
  
  
  METHODS
  Samples of renal cortex and medulla (ten patients) or renal cortex alone (13 patients) were taken from kidneys resected because of malignant cancer, from a site opposite to the cancer. Resections were performed in the 23 patients (seven female and 16 male) who were 52-82 years old. The material was stored at -72 oC.
  
  
  RESULTS
  Activity of D1 in renal cortex was 3.785 ± 2.041 fmol 125I/mg protein/minute and activity of D2 was 0.236 ± 0.125 fmol 125I/mg protein/minute. There was a strong positive correlation between D1 and D2 activities in renal cortex (r = 0.890, p 〈 0.001). Activity of D1 in renal medulla was 2.157 ± 2.176 fmol 125I/mg protein/minute, and activity of D2 was 0.168 ± 0.095 fmol 125I/mg protein/minute. A positive correlation between D1 and D2 in renal medulla (r = 0.661, p = 0.038) was observed as well. Activities of D1 in cortex and medulla were strongly and positively associated (r = 0.794, p = 0.006), whereas there was no correlation between the activities of D2 in cortex and medulla (r = 0.224, p = 0.553).
  
  
  CONCLUSIONS
  Results presented in this study suggest that both cortical and medullary D1 and D2 may be involved in thyroid hormone metabolism. This finding could be of clinical relevance in patients with impaired renal function.
authors.affiliation: Department of Internal Medicine, Nephrology and Dialysotherapy, Military Institute of Medicine, Warsaw, Poland. snemczyk@wim.mil.pl
authors.forename: Stanisław
authors.initials: S
authors.lastname: Niemczyk
authors.forename: Marta
authors.initials: M
authors.lastname: Dudek
authors.forename: Zbigniew
authors.initials: Z
authors.lastname: Bartoszewicz
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Szamotulska
authors.forename: Lukasz
authors.initials: L
authors.lastname: Woźniacki
authors.forename: Dorota
authors.initials: D
authors.lastname: Brodowska-Kania
authors.forename: Longin
authors.initials: L
authors.lastname: Niemczyk
authors.forename: Władysław
authors.initials: W
authors.lastname: Małek
authors.forename: Joanna
authors.initials: J
authors.lastname: Matuszkiewicz-Rowińska
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007453:Iodide Peroxidase / Q000378:metabolism*; D007672:Kidney Cortex / Q000201:enzymology*; D007679:Kidney Medulla / Q000201:enzymology*; D007680:Kidney Neoplasms / Q000201:enzymology*; D008297:Male; D008875:Middle Aged; D013223:Statistics as Topic
chemical_list: D007453:Iodide Peroxidase