Comparative analysis of fecal fat quantitation via nuclear magnetic resonance spectroscopy (1H NMR) and gravimetry

BackgroundFecal-fat is typically measured by extracting lipid from homogenized feces with subsequent gravimetric/titrimetric analyses that are time-consuming and involve toxic solvents. Accordingly, an efficient and more safe method to quantitate fecal-fat is needed. The present objective was to adapt CEM SmartTrac® technology (i.e. 1H NMR) to rapidly (< 5 min) quantitate fecal-fat and compare 1H NMR and gravimetric performance characteristics.Methods1H NMR and gravimetric measurements of stool-fat were conducted using excess stool samples (72 h collection; n = 107) homogenized to semi-liquid consistency prior to analyses.ResultsThe 1H NMR method demonstrated acceptable linearity (R2 = 0.9999) and recovery (mean = 105%) with imprecision (intra-assay CV = 1.2–6.5%; inter-assay CV = 1.8–5.8%) comparable to or better than gravimetry (intra-assay CV = 1.0–17.2%; inter-assay CV = 3.8–6.5%). Excellent correlation between fecal-fat quantitation by 1H NMR and gravimetry (n = 107; R2 = 0.983; y = 1.0173x − 0.6859) was exhibited; moreover, 1H NMR demonstrated good sensitivity (92.3%), specificity (94.5%), negative-predictive value (92.9%) and positive-predictive value (94.1%) for malabsorption using the reference cut-off of ≤ 7 g fat/24 h.ConclusionsThese data demonstrate that 1H NMR permits rapid and safe quantitation of fecal-fat while maintaining acceptable performance characteristics, thereby supporting the utility of 1H NMR as an alternative method to gravimetry for fecal-fat quantitation.