Comparison of steatocrit and fat absorption in persons with cystic fibrosis

Abstract

BACKGROUND: Exocrine pancreatic insufficiency is a common problem in persons with cystic fibrosis causing malabsorption and poor growth. The 72-hour fecal fat study is the best qualitative measure of fat malabsorption used in clinical practice. This test has several drawbacks, which include cost and logistics. The steatocrit has been proposed as a rapid method to assess fat malabsorption.

OBJECTIVES: The objective of this study was to determine whether the steatocrit is an accurate estimation of fat malabsorption in persons with cystic fibrosis.

METHODS: Forty-nine stool samples for steatocrit processing were obtained from 72-hour fecal fat collections performed on twenty-seven persons with cystic fibrosis. Stools were weighed and homogenized with sand and water. The emulsified specimen was pipetted into heparinized capillary tubes and centrifuged for 15 minutes. The length of the fatty layer was compared to the length of the solid layer plus the fatty layer in each tube to determine the steatocrit value. Four steatocrit mixtures were evaluated: (1) standard steatocrit, (2) dilute steatocrit, (3) acid steatocrit, (4) dilute acid steatocrit. Steatocrit values were compared with the coefficient of fat absorption determined from the 72-hour fecal fat collection.

RESULTS: The correlation coefficient of the steatocrit and the coefficient of fat absorption ranged from -.045 to -.491. Only the coefficient of fat absorption and the acid steatocrit had a significant correlation ( = 0.033).

CONCLUSION: The steatocrit is an imprecise measure of fat absorption and not clinically useful in estimating steatorrhea.