title: Sex-specific differences in the concentration of tubular parameters in the amniotic fluid of second trimester fetuses.
abstract: OBJECTIVE
  Renal dysplasia and obstructive uropathy are more common in males and are associated with an increased tubular loss of electrolytes. We aimed to compare the midtrimester concentration of tubular parameters in the prenatal period between healthy male and female fetuses.
  
  
  METHODS
  Amniotic fluid was collected at 16 weeks of gestation at the time of genetic amniocentesis. The concentration of sodium, chloride, potassium, calcium, phosphate, magnesium, α1-microglobulin, creatinine and urea was determined in the amniotic fluid of 92 male and 108 female fetuses.
  
  
  RESULTS
  The concentration of sodium, chloride and calcium was not significantly higher in male than in female fetuses. In contrast, the concentration of potassium (p=0.01), phosphate (p=0.04), magnesium (p=0.04) and α1-microglobulin (p=0.04) was significantly increased in the amniotic fluid of male fetuses. The concentration of electrolytes correlated to the concentration of creatinine, urea and α1-microglobulin.
  
  
  CONCLUSIONS
  The concentration of specific tubular parameters in the amniotic fluid was higher in male compared with female fetuses. Whether this might point to sex-specific differences in tubular function in second trimester fetuses or reflect glomerular filtration or other interfering factors remains speculative.
authors.affiliation: Department of Paediatrics and Adolescent Medicine, University of Erlangen-Nuremberg, Erlangen, Germany.
authors.forename: Anja
authors.initials: A
authors.lastname: Tzschoppe
authors.forename: Manfred
authors.initials: M
authors.lastname: Rauh
authors.forename: Tamme W
authors.initials: TW
authors.lastname: Goecke
authors.forename: Britta
authors.initials: B
authors.lastname: Yazdi
authors.forename: Nicola
authors.initials: N
authors.lastname: Hart
authors.forename: Jörn
authors.initials: J
authors.lastname: Siemer
authors.forename: Ralf L
authors.initials: RL
authors.lastname: Schild
authors.forename: Jörg
authors.initials: J
authors.lastname: Dötsch
mesh_terms: D000653:Amniotic Fluid / Q000378:metabolism*; D015415:Biomarkers / Q000378:metabolism; D005260:Female; D005315:Fetal Diseases / Q000175:diagnosis; D006801:Humans; D007231:Infant, Newborn; D007684:Kidney Tubules / Q000378:metabolism*; D008297:Male; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D012016:Reference Values; D012727:Sex Characteristics; D014570:Urologic Diseases / Q000175:diagnosis
chemical_list: D015415:Biomarkers