CTSB and fetal growth restriction: They found that cathepsin B activity in the urine was statistically significantly increased in preterm children, and even more increased in neonates with IUGR, when compared to the control group (median, (Q1–Q3)): 2.303, (1.7–2.582); 3.633, (2.146–4.848); 1.044, (0.8335–1.372) IU/min mmol, respectively.