The applicability of acid steatocrit in cystic fibrosis infants

Abstract

Background: Steatorrhea, which is a consequence of pancreatic insufficiency, occurs in 85% of patients with cystic fibrosis. In clinical practice, fecal fat concentration is used to diagnose and monitor fecal fat losses. Because compliance with this method is insufficient, new tests are needed. One of the alternatives may be the acid steatocrit. Aim: This study aimed to investigate the value of acid steatocrit in the assessment of fecal fat excretion in pancreatic-insufficient infants with cystic fibrosis: before and after the initiation of pancreatic enzyme supplementation. Patients and methods: The study included 10 infants with cystic fibrosis diagnosed through the newborn screening program and 16 healthy control infants. In all the children, fecal elastase-1, fecal fat concentration (%) and acid steatocrit were measured. Results: Fecal fat concentration in cystic fibrosis infants (range: 14.5%–32,1%) was significantly higher (p<0.0001) compared with control subjects (1.7%–15.1%). Acid steatocrit in cystic fibrosis (19.8%–68.7%) was also greater (p<0.0001) than in the control group (10.7%–22.7%). The area under the receiver operating characteristic curve (ROC) for the 95th percentile of normal values was 0.981 (95% confidence interval: 0.941–1.0) indicating high diagnostic accuracy of acid steatocrit. When acid steatocrit and fecal fat concentration cut-offs were set at 90th and 95th percentile for healthy infants, the specificity of acid steatocrit in detecting elevated fecal fat concentration was 100%, and the sensitivity 80% and 100%, respectively. Conclusions: Compared with the assessment of fecal fat concentration, sensitivity/specificity of acid steatocrit in steatorrhea detection in infants are potentially lower, but still satisfactory. The measurement of acid steatocrit may constitute a useful method of fecal fat concentration assessment in infants identified by the newborn screening program in whom the replacement enzyme therapy has not yet been commenced.

Keywords

• faecal fat concentration
• faecal fat excretion
• enzymatic supplementation
• exocrine pancreatic function