A low serum alkaline phosphatase (ALP) level is an uncommon finding in patients with chronic liver disease (CLD). The prevalence of this finding and whether low ALP expression influences CLD remain to be determined. The objectives of this study were: (1) to document the prevalence of low serum ALP levels in adult CLD patients and (2) compare features of CLD in patients with low versus normal or elevated serum ALP levels.

An adult, outpatient liver disease database was searched for patients with low serum ALP levels (<40 IU/L). Hepatic inflammation, function, fibrosis and disease severity were determined by serum aminotransferases, albumin, bilirubin and INR levels, Fib-4 calculations and MELD scores respectively.

Of 19,037 patients entered into the database, 47 (0.25%) had consistently low serum ALP levels, 51 (0.27%) low levels on the majority and 469 (2.44%) on the minority of determinations. Patients with consistently low levels were matched (1:2) by age, gender and nature of the underlying liver disease to patients with normal or elevated serum ALP levels. Matched patients with consistently low ALP levels had significantly lower serum aminotransferase and bilirubin levels at their initial visit and throughout the follow-up period (p < 0.05 respectively) while Fib-4 levels and MELD scores were similar at the initial and last follow-up visit.

These results establish the prevalence of low serum ALP levels in adult CLD patients and describe a hitherto unreported association between low serum ALP levels and less biochemical evidence of active disease.