title: Are low erythropoietin and 1,25-dihydroxyvitamin D levels indicative of tubulo-interstitial dysfunction in diabetes without persistent microalbuminuria?
abstract: OBJECTIVE
  To investigate the relationship between Erythropoietin (EPO) and 1,25-dihydroxyvitamin D levels, and tubular damage in patients with diabetes mellitus (DM) without persistent microalbuminuria.
  
  
  METHODS
  We measured serum EPO and 1,25-dihydroxyvitamin D levels and tubular injury markers such as urinary N-acetyl-beta-d-glucosaminidase (NAG) and retinol binding protein (RBP) levels in 41 non-diabetic controls, 40 patients with Type 1 and 40 with Type 2 DM.
  
  
  RESULTS
  Median serum EPO levels were lower in Type 1 (2.57 mIU/ml: p<0.001) and Type 2 DM (5.69 mIU/ml: p=0.044) than in controls (8.76 mIU/ml), though haemoglobin levels did not differ. Median 1,25-dihydroxyvitamin D levels were lower in Type 1 (41.0 pmol/l: p=0.001) and Type 2 DM (41.8 pmol/l: p=0.035) than in controls (56.1 pmol/l), though serum creatinine, calcium, phosphate and PTH levels did not differ. Median RBP excretion was higher in Type 2 DM (0.35 mg/l vs. 0.23 mg/l: p=0.013) than in controls. Median NAG excretion was higher in Type 1 DM (1,079 micromol/h vs.1,030 micromol/h: p=0.048) compared to controls.
  
  
  CONCLUSIONS
  Tubulo-interstitial damage with low levels of EPO and 1,25-dihydroxyvitamin D occurs early in Type 1 and Type 2 DM before persistent microalbuminuria.
authors.affiliation: Renal Unit, East and North Herts NHS Trust, SG1 4AB UK. dsingh4@nhs.net
authors.forename: Dhruv K
authors.initials: DK
authors.lastname: Singh
authors.forename: Peter
authors.initials: P
authors.lastname: Winocour
authors.forename: Bev
authors.initials: B
authors.lastname: Summerhayes
authors.forename: Adie
authors.initials: A
authors.lastname: Viljoen
authors.forename: G
authors.initials: G
authors.lastname: Sivakumar
authors.forename: Ken
authors.initials: K
authors.lastname: Farrington
mesh_terms: D000328:Adult; D000419:Albuminuria / Q000097:blood*; D001786:Blood Glucose / Q000378:metabolism; D001794:Blood Pressure; D003404:Creatinine / Q000097:blood; D003920:Diabetes Mellitus / Q000097:blood*; D003922:Diabetes Mellitus, Type 1 / Q000097:blood* / Q000503:physiopathology; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000503:physiopathology; D003928:Diabetic Nephropathies / Q000097:blood*; D004921:Erythropoietin / Q000097:blood*; D005260:Female; D006442:Glycated Hemoglobin / Q000378:metabolism; D006801:Humans; D007684:Kidney Tubules / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D055815:Young Adult
chemical_list: D001786:Blood Glucose; D003404:Creatinine; D004921:Erythropoietin; D006442:Glycated Hemoglobin; D014807:Vitamin D; C097949:1,25-dihydroxyvitamin D