title: [A comparative study of the sodium, potassium, urea, creatinine, and uric acid concentrations in the human amniotic fluid between weeks 15-20 and 38-42].
abstract: The amniotic fluid physiology is a dynamic process involving maternal and fetal compartments and depends on gestational age.
  
  
  OBJECTIVE
  To analyze the concentration of sodium, potassium, urea, creatinine, and uric acid in the amniotic fluid of normal pregnant women in the second and third trimester. Also, to evaluate the influence of maternal age, race, parity, and fetal sex on those elements.
  
  
  METHODS
  Fifty samples obtained by genetic amniocentesis (15-20 weeks, group I) and fifty obtained by elective cesarean section (38-42 weeks, group II) were analyzed. According to the variables we used the following statistical tests: Analysis of variance; Test t Student: Chi-square test; Mann-Whitney test (a 0.05 pounds).
  
  
  RESULTS
  In group II, urea, creatinine and uric acid levels were significantly higher than in group I. The sodium level was significantly lower in group II compared with group I. The potassium concentration did not show any significant difference in both groups. There was no significant interference of maternal age, race, parity and fetal sex in any of the five studied variables.
  
  
  CONCLUSIONS
  These findings were emphasized for prenatal diagnosis purposes and analysis of renal function. The authors suggest future comparisons of obtained "normal" data with pathological situations.
authors.affiliation: Departamento de Tocoginegologia, Universidade Federal de São Paulo, SP.
authors.forename: F A
authors.initials: FA
authors.lastname: Bauk
authors.forename: A F
authors.initials: AF
authors.lastname: Moron
authors.forename: N F
authors.initials: NF
authors.lastname: Novo
authors.forename: Y
authors.initials: Y
authors.lastname: Juliano
authors.forename: E B
authors.initials: EB
authors.lastname: Rodrigues
authors.forename: L
authors.initials: L
authors.lastname: Kulay
mesh_terms: D000649:Amniocentesis; D000653:Amniotic Fluid / Q000737:chemistry*; D000704:Analysis of Variance; D003404:Creatinine / Q000032:analysis*; D005260:Female; D006801:Humans; D008423:Maternal Age; D010298:Parity; D011188:Potassium / Q000032:analysis*; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D011263:Pregnancy Trimester, Third; D012964:Sodium / Q000032:analysis*; D014508:Urea / Q000032:analysis*; D014527:Uric Acid / Q000032:analysis*
chemical_list: D014527:Uric Acid; D014508:Urea; D012964:Sodium; D003404:Creatinine; D011188:Potassium