Urinary urobilinogen in biliary atresia: A missed, simple and cheap diagnostic test

Early diagnosis of biliary atresia (BA) is of utmost importance for good outcome; however, it is sometimes difficult due to the overlapping diagnostic test results with other causes of neonatal cholestasis. Moreover, many diagnostic tests are costly, invasive and not available in all centers, especially in developing countries. So, we aimed to investigate the diagnostic performance of urinary urobilinogen; an easy, cheap test that was not tested before in BA.

Seventy-five infants divided into three age- and sex-matched groups (BA, non-BA cholestasis and healthy control group) were recruited for the study. Each group comprised 25 infants. Urinary urobilinogen was measured for all infants using the modified Ehrlich's method.

Urinary urobilinogen was significantly lower in the BA group (0.31 ± 0.25 mg/dL) than both of the non-BA cholestasis (2.08 ± 3.48 mg/dL) and healthy control (0.53 ± 0.64 mg/dL) groups at P < 0.0001 and P < 0.001, respectively. Urinary urobilinogen at a cut-off value of 0.32 mg/dL or less can differentiate BA from other non-BA cholestasis with a sensitivity of 88% and a specificity of 72%. When this cut-off value was combined with γ-glutamyltransferase (γ-GT) at a cut-off value of 363 U/L or more, BA could be differentiated from other cholestatic disorders with a sensitivity of 80% and specificity of 100%. On the other hand, dipstick test could not differentiate between BA and non-BA cholestasis (P = 0.396).

Urinary urobilinogen is a simple, non-invasive, cheap, sensitive and specific marker, especially if combined with γ-GT, which can be used in diagnosis of BA, especially in developing countries.