Table 4.

Multivariate regressions on plasma concentrations (micromoles per liter), plasma ratios (no unit), and urinary excretion (micromoles per mole creatinine) of amino acids and amines in nondialyzed CKD patients

Dependent VariablesExplanatory VariableChange for 1 Unit Increase95% Confidence IntervalP ValueModel P Value
Plasma concentration
 Citrullinelog(eGFR)−27.2−42.4 to −12.10.0010.002
Diabetes (yes)16.83.1 to 30.40.02
 PhenylalanineHCO3−2.0−3.7 to −0.20.030.01
log(CRP)6.10.5 to 11.60.04
Weight0.320.03 to 0.610.04
 TryptophaneGFR0.310.04 to 0.580.030.02
 ADMAlog(eGFR)−0.47−0.69 to −0.24<0.001<0.001
Na+0.050.01 to 0.090.03
 Hydroxykynureninelog(eGFR)−1.7−2.3 to −1.2<0.001<0.001
Na+0.140.05 to 0.220.01
Plasma ratios
 EAA/NEAAeGFR0.0050.002 to 0.010.0010.01
Weight0.0030.0004 to 0.010.03
 Arg/CiteGFR0.040.02 to 0.06<0.0010.001
 Cit/OrneGFR−0.01−0.01 to −0.0010.020.01
 Val/GlyeGFR0.020.01 to 0.030.0020.004
Weight0.020.01 to 0.030.01
HCO3−0.07−0.13 to −0.010.03
 Arg/ADMAeGFR2.20.1 to 4.30.040.03
 ADMA/SDMAlog(eGFR)−0.76−1.29 to −0.230.010.002
Na+0.100.01 to 0.190.04
 OH-Kyn/Trplog(eGFR)−0.59−0.93 to −0.250.0020.003
Urinary excretion (logtransformed)
 Total EAAAge−0.02−0.05 to −0.0010.050.01
 Alaninelog(proteinuria)0.220.08 to 0.360.0040.04
 Asparaginelog(proteinuria)0.170.05 to 0.300.01<0.001
 Citrullinelog(eGFR)−1.0−1.7 to −0.40.01<0.001
log(proteinuria)0.250.02 to 0.480.04
 Lysinelog(CRP)−0.6−0.99 to −0.210.010.003
Albumin−0.18−0.30 to −0.060.01
 Phenylalaninelog(proteinuria)0.20.08 to 0.330.0040.003
 Prolinelog(eGFR)−1.0−1.6 to −0.40.004<0.001
log(proteinuria)0.310.1 to 0.510.01
 Tyrosinelog(proteinuria)0.180.05 to 0.310.010.02
 Valinelog(proteinuria)0.320.12 to 0.520.010.04
Na+−0.13−0.24 to −0.020.04
  • All models included age, sex, diabetes, weight, eGFR, proteinuria, serum HCO3, serum Na+, serum albumin, and serum CRP as covariates. eGFR, estimated GFR; CRP, C-reactive protein; ADMA, asymmetric dimethylarginine; EAA, sum of essential amino acids; NEAA, sum of nonessential amino acids; Arg, arginine; Cit, citrulline; Orn, ornithine; Val, valine; Gly, glycine; SDMA, symmetric dimethylarginine; OH-Kyn, hydroxykynurenine; Trp, tryptophan.