Assessment of 'nucleation time' as a predictor of cholelithiasis

In the formation of gallstones, crystal nucleation is a key step, which is followed by precipitation and gradual growth of cholesterol crystals.

A case-control study was carried out among 60 patients (30 patients, 14 males and 16 females, median age of 36 years, range 33-71 years, body mass index (BMI)=25.1+/-0.33 kg/m, who underwent laparoscopic cholecystectomy; 30 control individuals, 15 males and 15 females, median age of 38 years, range 33-70 years, BMI=24.5+/-0.23 kg/m, who underwent laparotomy and who had normal ultrasound scans of the gallbladder and no demonstrable stones). Bile aspirated from the common bile duct was ultrafiltered and anaerobically incubated at 37 degrees C. Incubated bile was examined daily by polarized light microscopy, for appearance of cholesterol crystals. Nucleation time (NT) of bile was assessed as the time taken for the first crystals to appear under polarized light microscopy.

Age and BMI of control individuals were not different to those of cases studied. The overall mean NT was significantly shorter in patients versus controls (mean NT+/-SEM: patients, 1.76+/-0.2 days; vs. controls, 12.74+/-0.4 days, P=0.001). Of control individuals, females demonstrated a shorter NT compared with males (mean NT+/-SEM: females, 11.4+/-0.36 days; vs. males, 14.1+/-0.46 days, P=0.006). In contrast, there was no sex difference in NT in patients (mean NT+/-SEM: females, 1.7+/-0.24 days; vs. males, 1.8+/-0.2 days, P=0.7).

NT in control individuals without gallstones was significantly prolonged compared with the NT in patients with established gallstone disease. Among the control individuals, females had a significantly shorter NT than males. Hence, the assessment of NT is predictor of cholelithiasis.