Diagnostic Approach to Suspected Gallbladder Disease

Essential Initial Blood Tests

The American Gastroenterological Association recommends obtaining liver function tests (LFTs) including alkaline phosphatase (ALP), gamma-glutamyl transpeptidase (GGT), bilirubin (total and direct), AST, and ALT, along with a complete blood count (FBC) and coagulation studies (INR/PT) if intervention is anticipated in patients with suspected gallbladder disease 1, 2
Alkaline phosphatase (ALP) is the most sensitive marker for biliary obstruction, with 92% sensitivity at cut-off >125 IU/L 5, 6
Gamma-glutamyl transpeptidase (GGT) is the most reliable LFT for common bile duct stones (CBDS) with 80.6% sensitivity and 75.3% specificity at cut-off of 224 IU/L 3
Total and direct bilirubin are elevated in 60-77% of patients with CBDS; at cut-off >22.23 μmol/L has 84% sensitivity and 91% specificity 3, 5, 6
Elevated ALT is a predictor of CBDS with 90% of CBDS patients showing elevation 3, 6
Serum albumin assesses hepatic synthetic function and chronic disease 4, 7
A complete blood count (FBC) is required before any biliary intervention; leucocytosis combined with elevated bilirubin may predict gangrenous cholecystitis 1, 2, 6
INR/PT is mandatory prior to ERCP or biliary sphincterotomy 1, 2

Elevated LFTs alone are insufficient to diagnose common bile duct stones and should not be used as the sole method to identify CBDS 3, 6
Normal LFTs have 97% negative predictive value but abnormal LFTs have only 15% positive predictive value for CBDS 3, 6
In acute cholecystitis, 15-50% of patients show elevated LFTs without CBDS due to inflammatory processes rather than obstruction 3, 6

When intrahepatic ducts are dilated without extrahepatic dilation, CA 19-9 is elevated in up to 85% of cholangiocarcinoma; >100 U/ml has 75% sensitivity and 80% specificity 8, 9
For chronic cholestasis with elevated ALP/GGT, anti-mitochondrial antibodies (AMA) are diagnostic for primary biliary cholangitis with >95% specificity 10, 11
In cases of suspected sepsis or cholangitis, C-reactive protein (CRP) evaluates severity of inflammation, procalcitonin (PCT) predicts fatal progression in septic patients, and serum lactate is associated with poor outcomes and increased mortality 4, 7