Use of Serum Vitamin B12 Level as a Marker to Differentiate Idiopathic Noncirrhotic Intrahepatic Portal Hypertension from Cryptogenic Cirrhosis

Abstract

Idiopathic non-cirrhotic intrahepatic portal hypertension (NCIPH) is often mis-diagnosed as cryptogenic cirrhosis. Serum vitamin B12 levels can be raised in cirrhosis, probably because of excess release or reduced clearance. Because NCIPH is characterised by long periods of preserved liver function, we examined whether serum B12 level could be used as a marker to differentiate NCIPH from cryptogenic cirrhosis. We analysed serum B12 levels in 45 NCIPH and 43 cryptogenic cirrhosis patients from January 2009 to September 2011. Serum B12 levels were significantly lower in NCIPH patients than in cryptogenic cirrhosis patients (p < 0.001) and were useful in differentiating the two disorders (area under ROC: 0.84; 95% C.I: 0.76-0.93). Low serum B12 level (≤250 pg/ml) was noted in 25/72 (35%) healthy controls, 14/42 (33%) NCIPH patients, and 1/38 (3 %) cryptogenic cirrhosis patients. In patients with intrahepatic portal hypertension of unknown cause, serum B12 level ≤ 250 pg/ml was useful for diagnosing NCIPH (positive predictive value: 93 %, positive likelihood ratio 12.7), and serum B12 level >1,000 pg/ml was useful in ruling out NCIPH (negative predictive value: 86 %, negative likelihood ratio: 6.67). Low serum B12 levels (≤250 pg/ml) correlated with diagnosis of NCIPH after adjusting for possible confounders (O.R: 13.6; 95% C.I:1.5-126.2). Among patients in Child's class A, serum B12 level was ≤250 pg/ml in 14/35 NCIPH patients compared with 1/21 cryptogenic cirrhosis patients (O.R: 13.3; 95% C.I: 1.6-111). Serum vitamin B12 level seems to be a useful non-invasive marker for differentiation of NCIPH from cryptogenic cirrhosis.