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

BACKGROUND Fecal-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. (1)H NMR) to rapidly (< 5 min) quantitate fecal-fat and compare (1)H NMR and gravimetric performance characteristics. METHODS (1)H 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. RESULTS The (1)H NMR method demonstrated acceptable linearity (R(2)=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 (1)H NMR and gravimetry (n=107; R(2)=0.983; y=1.0173x-0.6859) was exhibited; moreover, (1)H 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 < or = 7 g fat/24 h. CONCLUSIONS These data demonstrate that (1)H NMR permits rapid and safe quantitation of fecal-fat while maintaining acceptable performance characteristics, thereby supporting the utility of (1)H NMR as an alternative method to gravimetry for fecal-fat quantitation.