Document Detail

Urea kinetics in healthy women during normal pregnancy.
MedLine Citation:
PMID:  9135365     Owner:  NLM     Status:  MEDLINE    
Urea kinetics were measured in normal women aged 22-34 years at weeks 16, 24 and 32 on either their habitual protein intake (HABIT) or a controlled intake of 60 g protein/d (CONTROL), using primed-intermittent oral doses of [15N15N]urea and measurement of plateau enrichment in urinary urea over 18 h (ID) or a single oral dose of [15N15N]urea and measurement of enrichment of urea in urine over the following 48 h (SD). The intake of protein during HABIT-ID (80 g/d) was greater than that on HABIT-SD (71 g/d); urea production as a percentage of intake was significantly greater at week 16 for HABIT-ID than HABIT-SD, whereas urea hydrolysis at week 16 was greater for HABIT-SD than HABIT-ID and urea excretion at week 32 was greater for HABIT-ID than HABIT-SD. The combined results for HABIT-ID and HABIT-SD showed a significant reduction in urea production at week 32 compared with week 24. Urea excretion decreased significantly from week 16 to week 24 with no further decrease to week 32 and urea hydrolysis was significantly greater at week 24 than either week 16 or week 32. Compared with HABIT, on CONTROL there was a decrease in urea production at week 16, and urea excretion was significantly reduced at week 16. For all time periods urea production was closely related to the sum of intake plus hydrolysis. Hydrolysis was greatest at week 24 and closely related to urea production. There was a significant inverse linear relationship overall for hydrolysis as a proportion of production and excretion as a proportion of intake. The results show that on HABIT N is more effectively conserved in mid-pregnancy through an increase in urea hydrolysis and salvage, and during late pregnancy through a reduction in urea formation. Lowering protein intake at any stage of pregnancy increased the hydrolysis and salvage of urea. The staging of these changes was later than that in pregnancy in Jamaica.
I S McClelland; C Persaud; A A Jackson
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The British journal of nutrition     Volume:  77     ISSN:  0007-1145     ISO Abbreviation:  Br. J. Nutr.     Publication Date:  1997 Feb 
Date Detail:
Created Date:  1997-05-15     Completed Date:  1997-05-15     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0372547     Medline TA:  Br J Nutr     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  165-81     Citation Subset:  IM    
Department of Human Nutrition, University of Southampton.
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MeSH Terms
Diet, Protein-Restricted
Dietary Proteins / metabolism*
Longitudinal Studies
Nitrogen Isotopes
Nutritional Requirements
Pregnancy / metabolism*
Pregnancy Trimester, Second
Pregnancy Trimester, Third
Urea / pharmacokinetics*,  urine
Reg. No./Substance:
0/Dietary Proteins; 0/Nitrogen Isotopes; 57-13-6/Urea

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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