title: Effect of posture on creatinine clearance in late pregnancy  and after pregnancy.
abstract: OBJECTIVE
  To assess creatinine clearance that indicates glomerular filtration rate (GFR) and to demonstrate the effect of posture on creatinine clearance in late pregnancy compared to the non-pregnant state.
  
  
  METHODS
  Twenty-six healthy pregnant women aged 19-30 years were studied for two sessions, first in their third trimester of pregnancy and then in a non-pregnant state at 6-12 weeks after delivery. In both sessions, creatinine clearance was assessed at three periods: the 24-h baseline, and at the end of 2-h sitting and 2-h lying (in left lateral decubitus position) periods. Urine and blood samples were collected for creatinine clearance measurement.
  
  
  RESULTS
  The results showed that the 24-h creatinine clearance in late pregnancy was 28.3% higher than that in the non-pregnant state (122.6 +/- 26.2 vs 95.3 +/- 15.1 mL/min per 1.73 m2, P < 0.001). In late pregnancy, after 2-h sitting, creatinine clearance decreased significantly (10%) compared to the 24-h baseline (122.6 +/- 26.2 vs 110.4 +/- 28.6 mL/min per 1.73 m2, P < 0.001). Creatinine clearance rose back to the high baseline level after the pregnant woman laid in left lateral decubitus for 2 h. The decrease in creatinine clearance during prolonged sitting was not seen in the non-pregnant state. At any posture, the creatinine clearance was always higher in the pregnant state than in the non-pregnant.
  
  
  CONCLUSIONS
  This study showed that creatinine clearance in late pregnancy was much higher than in the non-pregnant state, and was affected by sitting for up to 2 h. It might be wise for women to lay down in the left lateral decubitus position for a while after many hours of sitting when pregnancy is approaching its term.
authors.affiliation: Department of Physiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand. sislr@mahidol.ac.th
authors.forename: Supatra
authors.initials: S
authors.lastname: Lohsiriwat
authors.forename: Nathi
authors.initials: N
authors.lastname: Imrittha
mesh_terms: D000328:Adult; D003404:Creatinine / Q000097:blood / Q000493:pharmacokinetics* / Q000652:urine; D005260:Female; D005865:Gestational Age; D005919:Glomerular Filtration Rate; D006801:Humans; D008657:Metabolic Clearance Rate; D049590:Postpartum Period / Q000378:metabolism*; D011187:Posture / Q000502:physiology*; D011247:Pregnancy; D011263:Pregnancy Trimester, Third
chemical_list: D003404:Creatinine