Newly established LC-MS/MS method for measurement of plasma BH4 as a predictive biomarker for kidney injury in diabetes

The clinical research on BH4 is limited because of the difficulties on its measurement. In this study, we used our own established LC-MS/MS method to examine the plasma BH4 levels in diabetes to determine whether it could be used as a biomarker for the prediction of kidney injury in those patients.Hospitalized diabetes patients in Renmin Hospital of Wuhan University from Jan to Aug 2021 were recruited. To assess the association between plasma BH4 with ACR or eGFR in diabetes, a total of 142 patients with type 2 diabetes (T2DM) were enrolled. They were divided into three groups by albuminuria levels: normoalbuminuria (n = 68), microalbuminuria (n = 48), and macroalbuminuria (n = 26) according to ACR; or into two groups by eGFR: eGFR≥90 or eGFR90 ml/min for correlation and logistic regression analysis. Plasma BH4 level was measured by LC-MS/MS along with other biochemical indices.Plasma BH4 concentrations were decreased as ACR progressed. BH4 (r = -0.55, P 0.001) and 2h C-Peptide (CP-2h) (r = -0.248, P = 0.003) levels were negatively correlated with ACR. Moreover, multivariable logistic regression analysis showed BH4 concentrations (B = -0.468, P 0.001) and CP-2h (B = -0.257, P = 0.028) were independently associated with ACR progression. ROC curve showed that BH4 level has a predictive value on ACR (95%CI 0.686-0.841, sensitivity 69.1%, specificity 73%). Moreover, in diabetes patients with eGFR≥90 ml/min, plasma BH4 level (P = 0.008) is higher than those in diabetes with eGFR90 ml/min and BH4 was remained independently associated with eGFR after multivariable logistic regression analysis (B = -0.193, P = 0.048).Our established LC-MS/MS method could be used on human plasma BH4 measurements and our data suggested that BH4 level can be used as a biomarker for kidney injury in diabetes indicated by its association with ACR progression and early renal function decline.