title: Creamatocrit analysis of human milk overestimates fat and energy content when compared to a human milk analyzer using mid-infrared spectroscopy.
abstract: OBJECTIVE
  Human milk (HM) is the preferred feeding for human infants but may be inadequate to support the rapid growth of the very-low-birth-weight infant. The creamatocrit (CMCT) has been widely used to guide health care professionals as they analyze HM fortification; however, the CMCT method is based on an equation using assumptions for protein and carbohydrate with fat as the only measured variable. The aim of the present study was to test the hypothesis that a human milk analyzer (HMA) would provide more accurate data for fat and energy content than analysis by CMCT.
  
  
  METHODS
  Fifty-one well-mixed samples of previously frozen expressed HM were obtained after thawing. Previously assayed "control" milk samples were thawed and also run with unknowns. All milk samples were prewarmed at 40°C and then analyzed by both CMCT and HMA. CMCT fat results were substituted in the CMCT equation to reach a value for energy (kcal/oz). Fat results from HMA were entered into a computer model to reach a value for energy (kcal/oz). Fat and energy results were compared by paired t test with statistical significance set at P < 0.05. An additional 10 samples were analyzed locally by both methods and then sent to a certified laboratory for quantitative analysis. Results for fat and energy were analyzed by 1-way analysis of variance with statistical significance set at P < 0.05.
  
  
  RESULTS
  Mean fat content by CMCT (5.8 ± 1.9 g/dL) was significantly higher than by HMA (3.2 ± 1.1 g/dL, P < 0.001). Mean energy by CMCT (21.8 ± 3.4 kcal/oz) was also significantly higher than by HMA (17.1 ± 2.9, P < 0.001). Comparison of biochemical analysis with HMA of the subset of milk samples showed no statistical difference for fat and energy, whereas CMCT was significantly higher than for both fat (P < 0.001) and energy (P = 0.002).
  
  
  CONCLUSIONS
  The CMCT method appears to overestimate fat and energy content of HM samples when compared with HMA and biochemical methods.
authors.affiliation: Neonatal Nutrition Research Laboratory, University of Louisville, Louisville, Kentucky 40292, USA.
authors.forename: Edward F
authors.initials: EF
authors.lastname: O'Neill
authors.forename: Paula G
authors.initials: PG
authors.lastname: Radmacher
authors.forename: Blake
authors.initials: B
authors.lastname: Sparks
authors.forename: David H
authors.initials: DH
authors.lastname: Adamkin
mesh_terms: D003198:Computer Simulation; D004040:Dietary Carbohydrates / Q000032:analysis; D004041:Dietary Fats / Q000032:analysis*; D004044:Dietary Proteins / Q000032:analysis; D002149:Energy Intake; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D019102:Infant, Very Low Birth Weight; D008895:Milk, Human / Q000737:chemistry*; D008954:Models, Biological; D015203:Reproducibility of Results; D013055:Spectrophotometry, Infrared / Q000379:methods*
chemical_list: D004040:Dietary Carbohydrates; D004041:Dietary Fats; D004044:Dietary Proteins