Evaluation of blood levels of nitric oxide as a means of differentiation between neonatal hepatitis and extrahepatic biliary atresia: A pilot study

Aim: The differentiation between neonatal hepatitis (NH) and extrahepatic biliary atresia (EHBA) is not always possible despite all the currently available diagnostic modalities. In this study, an attempt has been made to evaluate the role of nitric oxide (NO) levels in the peripheral blood to differentiate between the two conditions, one requiring early surgical intervention (EHBA) and the other amenable to conservative medical management (NH).

Patients and methods: Twenty patients who presented to the pediatric surgical service, over a 2 years period, with features of neonatal cholestasis were enrolled in the study. The diagnostic workup included documentation of history and clinical examination, biochemical liver function tests, ultrasonography, hepatobiliary scintigraphy (HS), and magnetic resonance cholangio-pancreaticography (MRCP). These patients did not show excretion on HS and intrahepatic ducts on MRCP. Hence, they were subjected to mini-laparotomy and operative cholangiography (OC). The EHBA patients were treated with the Kasai's portoenterostomy procedure, and the extrahepatic ducts were flushed with normal saline in NH patients. All patients were evaluated preoperatively for levels of NO in the peripheral blood by the Greiss reaction spectrophotometrically at 540 nm. Normal values were determined from a cohort of controls. The median (range) levels of NO in patients with EHBA and NH were compared, and the statistical significance of the difference was calculated by applying the Wilcox Rank Sum test. A P = 0.05 was considered as significant.

Results: Of the 20 patients enrolled in the study, 17 patients were treated for EHBA (Group I) and the remaining 3 patients had patent ducts on OC and were thus diagnosed as NH (Group II). The mean age of the patients in Groups I and II was comparable: 2.79 ± 0.75 and 2.67 ± 0.58 months, respectively (P = 0.866). The median NO levels were significantly elevated in each of the two groups as compared to the controls (5.6 μmol/l, range 1.26-11.34 μmol/l); when compared among themselves, the NO levels were significantly higher in Group I, 64.05 μmol/l (range 24.11-89.43 μmol/l), when compared with Group II, 41.72 μmol/l (range 23.53-45.63 μmol/l) (P = 0.022).

Conclusion: The serum levels of NO were found to be significantly higher in patients with EHBA as compared to those with NH. Hence, this may be a useful biochemical marker for the preoperative differentiation of EHBA from NH. However, a larger study is required for establishing the validity of the statistical significance.