Diffuse transmitted spectroscopy in conjunction with spectral peak averaging as a potential tool for noninvasive creatinine screening

Creatinine(Cr)is a biochemical waste molecule generated from muscle metabolism and primarily cleared from the bloodstream by the kidneys.If kidney function declines,Cr levels in the blood tend to increase.Therefore,Cr serves as an indicator of kidney function.In this work,we present a simple method for the rapid screening for impaired renal function based on the subject's Cr concentration.In our setup,broadband white light is delivered to a finger clamp through a fiber-optic cable to illuminate the patient's finger.The light is transmitted through the finger and collected by a second optical fiber coupled to a visible-near-infrared(VisNIR)spectrometer which covers the spectral range from 400nm to 1100nm.During the calibration process,the transmitted spectra acquired from 60 patients were measured.An average was calculated using the peak level of the transmitted,diffused intensity at three different wavelengths to create a"Cr intensity index".Patients were divided into five groups according to their Cr concentration levels,ranging from 1 mg/dL to 13 mg/dL.Our observations indicated that each group featured a unique spectral fingerprint.Next,we tested the index on 20 patients not included in the cali-bration procedure(unknown samples).We were able to classify patients into groups according to their Cr level with moderate prediction accuracy(R^(2)=0.55)and mean screening error of up to 16%.Future efforts will evaluate the accuracy of this approach with larger patient populations representing a broad range of Cr concentration.Still,this preliminary work is an essential step toward developing this useful noninvasive Cr screening platform using NIR light spectroscopy.

Determination of creatinine level in patient blood samples by Fourier NIR spectroscopy and multivariate analysis in comparison with biochemical assay

In this paper,in vivo spectra from 23 patients'blood samples with various Creatinine(Cr)concentration levels ranging from 0.96 to 12.5 mg/dL were measured using Fourier transform near-infrared spectrometer(FT-NIRS)and spectrum quantitative analysis method.Since Cr undergoes passive filtration,it serves as a key biomarker of kidneys function via the estimation of glomerular filtration rate.Thus,increased blood Cr concentration reflects impaired renal func-tion.After spectra pre processing and outlier exclusion,a spectral model was developed based on partial least squares regression(PLSR)method,wherein Cr concentrations correlated with filtered NIR spectra across several peaks,where Cr is know n to absorb NIR light.Several statistical metrics were applied to estimate the model efficiency during data analysis.Comparison of spectra-derived concentrations to reference Cr measurements by the current gold-standard Jaffe's method held in hospital lab revealed a Cr prediction accuracy of 1.64 mg/dL with good corre-lation of R=0.9.Bland-Altman plots were used to compare between our calculations and ref-erence lab values and reveal minimal bias between the two.The finding presented the potential of FT-NIRS coupled with PLSR technique for Cr determination.