title: Vitamin D deficiency and insufficiency in patients with chronic kidney disease.
abstract: BACKGROUND
  Vitamin D deficiency is common among patients with chronic kidney disease (CKD). A higher level of serum vitamin D is expected in residents of the tropics in relation to inhabitants of non-tropical regions, due to greater sun exposure and increased production of vitamin D.
  
  
  OBJECTIVE
  To analyze serum levels of vitamin D, such as 25-hydroxyvitamin D - 25(OH)D, in Brazilian patients at the predialytic stage with CKD.
  
  
  METHODS
  We studied 125 patients (aged 57.4 ± 16.2 years, 78 were white and 55.2%, male), with creatinine 2.67 ± 1.73 mg/dL and creatinine clearance 43.7 ± 34.5 mL/min. Body mass index was 27.4 ± 4.7 kg/m², and waist circumference was 95.0 ± 14.0 cm. Calcium was 9.3 ± 0.6 mg/dL, intact parathormone (iPTH) 212.6 ± 221.2 pg/mL and serum albumin 4.2 ± 0.6 g/dL. The mean 25(OH)D was 23.9 ± 10.7 ng/mL.
  
  
  RESULTS
  Out of the 125 patients, we found that 92 (72.6%) had suboptimal levels of 25(OH)D < 30 ng/mL, and 65 (52%) had vitamin D insufficiency (15-29 ng/mL); 27 (21.5%) had deficiency (5-14 ng/mL) and only one patient had severe vitamin D deficiency <5 ng/mL. No differences were observed among the levels of 25 (H)D in stratified patients as to the CKD stage. Levels of 25(OH)D were higher among males (38.1 ± 20.6 versus 22.4 ± 9.7 ng/mL; p < 0.0001), and there was an inverse correlation between levels 25(OH)D and iPTH, proteinuria and abdominal circumference, and a positive correlation between 25(OH)D and calcium and serum albumin. Multivariate analysis only showed inverse correlation between serum 25(OH)D and iPTH and abdominal circumference.
  
  
  CONCLUSIONS
  Even though the Brazilian population live in a tropical region, most patients had suboptimal levels of serum vitamin D, and this pattern may play a role in the development of hyperparathyroidism.
authors.affiliation: Nefrology Service at Hospital das Clínicas at the Medical School of Universidade de São Paulo – FMUSP.
authors.forename: Herculano Ferreira
authors.initials: HF
authors.lastname: Diniz
authors.forename: Mariana Fadil
authors.initials: MF
authors.lastname: Romão
authors.forename: Rosilene Motta
authors.initials: RM
authors.lastname: Elias
authors.forename: João Egídio
authors.initials: JE
authors.lastname: Romão Júnior
mesh_terms: D001938:Brazil; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D051436:Renal Insufficiency, Chronic / Q000097:blood / Q000150:complications*; D014807:Vitamin D / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000150:complications* / Q000453:epidemiology*
chemical_list: D014807:Vitamin D