Urinary Excretion of Ten Amino Acids by Women During the Reproductive Cycle

Following Healthy Pregnancy by Nuclear Magnetic Resonance (NMR) Metabolic Profiling of Human Urine

“…Notably, the changes listed in Table include some detected for the first time to our knowledge in maternal urine, in a pregnancy context, namely those regarding: choline, creatinine, 4-DEA and 4-DTA, furoylglycine, GAA, 3-HBA, and lactate (noted as f in Table ). Furthermore, an increase was found here for leucine, contrary to other reports indicating decreased excretion late in pregnancy; , however, our observation is actually in agreement with an earlier report . In addition, the four still unassigned resonances (U1 to U4) play an important role in defining the compositional profile of maternal urine throughout pregnancy, particularly U1 and U2, which have significant variation between NP and f1st T ( p -value ≈ 10 –6 ), and between 2nd and 3rd T ( p -value ≈ 10 –7 ).…”

“…In this context, previous reports , have indicated that (a) excretion of alanine, glycine, histidine, serine, and threonine increases during pregnancy; (b) excretion of cysteine, leucine, lysine, phenylalanine, taurine, tyrosine, and valine increases early on and decreases later in gestation and (c) excretion of arginine, asparagine, glutamate, isoleucine, methionine, and ornithine is not expected to significantly change. In this work, results have shown that (a) alanine, glycine, histidine, and threonine were confirmed to increase in urine; (b) changes in excreted taurine and tyrosine were confirmed, while leucine varied differently than expected (↑ in 3rd T); and (c) out of the amino acids not expected to change significantly, isoleucine presented a marked increase in the third trimester, consistently however with an earlier report . In relation to the remaining amino acids, arginine, asparagine, cysteine, glutamate, methionine, phenylalanine, and ornithine were not detected (probably due to their too low concentrations for NMR observation: up to tens of μmol/L), whereas no significant changes could be measured for lysine, serine, and valine.…”

“…In this work, results have shown that (a) alanine, glycine, histidine, and threonine were confirmed to increase in urine; (b) changes in excreted taurine and tyrosine were confirmed, while leucine varied differently than expected (↑ in 3rd T); and (c) out of the amino acids not expected to change significantly, isoleucine presented a marked increase in the third trimester, consistently however with an earlier report. 40 In relation to the remaining amino acids, arginine, asparagine, cysteine, glutamate, methionine, phenylalanine, and ornithine were not detected (probably due to their too low concentrations for NMR observation: up to tens of μmol/L), whereas no significant changes could be measured for lysine, serine, and valine.…”

“…Furthermore, an increase was found here for leucine, contrary to other reports indicating decreased excretion late in pregnancy; 28,29 however, our observation is actually in agreement with an earlier report. 40 In addition, the four still unassigned resonances (U1 to U4) play an important role in defining the compositional profile of maternal urine throughout pregnancy, particularly U1 and U2, which have significant variation between NP and f1st T (pvalue ≈ 10 −6 ), and between 2nd and 3rd T (p-value ≈ 10 −7 ). The identification of additional resonances belonging to U1 and U2 spin systems was attempted by 2D NMR and STOCSY analysis (Table 2), however, no further compound assignments were achieved.…”

Exploring the impact of maternal nutritional status on the compositional profile of mid-trimester biofluids

“…Urine is the biofluid most frequently used to study nutrient intake (Gibney et al, 2005;Walsh et al, 2006;Playdon et al, 2016;), since it is the body's liquid waste repository (Wishart, 2008). At this point it is worth mentioning that during pregnancy the urine metabolome is also influenced by the remarkable physiological forces set in motion by conception (Miller et al, 1954). Within this frame, the excretion of alanine increases rapidly in early pregnancy and continues to increase as pregnancy proceeds (Hytten and Cheyne, 1972).…”