A Case of Persistently Elevated Intestinal Alkaline Phosphatase Levels in Benign Hyperphosphatasemia

An increase in intestinal alkaline phosphatase (ALP) levels may explain elevated serum ALP levels observed, albeit without clinical significance.A 56-year-old Korean woman consistently presented with elevated intestinal ALP levels, ranging from 215 U/L to 599 U/L since 2018.Despite undergoing multiple esophagogastroduodenoscopies and colonoscopies, as well as additional imaging studies, no significant abnormalities were detected.Other liver function markers, such as aminotransferases, gamma-glutamyl transferase, and bilirubin, have consistently remained within reference intervals.The patient has not been on any medication except for thyroxine, which was prescribed following surgery for a thyroid nodule 20 years ago.Despite a B blood type, which is often associated with higher levels of intestinal ALP, previous studies have indicated that increases in intestinal ALP levels usually fall within reference intervals.Additionally, it has been noted that ALP levels can rise postprandially.However, the ALP levels in this patient have continued to increase irrespective of her fasting status.Given the lack of serological, pathological, or radiological anomalies, the diagnosis of benign familial hyperphosphatasemia should be considered.This case may represent the first documented instance of benign familial hyperphosphatasemia in Korea.Confirming the diagnosis may require evaluating ALP levels in the patient's relatives.It is crucial for physicians to recognize this benign condition to reassure patients and their families experiencing hyperphosphatasemia, thus preventing unnecessary investigations.