2230 Benign Intermittent Intestinal Alkaline Phosphatase Elevation

Abstract

INTRODUCTION: Liver function tests (LFTs) are commonly checked during routine clinical encounters without specific signs or symptoms. An elevated alkaline phosphatase (AP) level is followed by investigative algorithms to identify the etiology. Total AP comprises liver, bone and intestinal fractions. Elevated intestinal alkaline phosphatase (IAP) can occur as a rare benign condition or due to intestinal pathologies. Unlike previously published reports of benign persistent IAP elevation, our patient had intermittent elevation of IAP. CASE DESCRIPTION/METHODS: A 48-year-old obese female was seen in liver clinic for evaluation of elevated AP for the last two years. She had undergone work-up for elevated AP on several occasions but the exact etiology was not found. She did not report any prior history of jaundice, pruritis, nausea, vomiting, diarrhea, abdominal pain, arthralgias or arthritis. She denied any family history of elevated IAP. She was found to have elevated total AP on 6 separate occasions over the last 18 months ranging from 186 to 239 U/l (normal < 117). Her fasting isozyme fractionation was checked 4 times. She had elevated total AP and normal liver/bone fractions on all occasions but twice had elevated IAP of 62 and 93 U/l (normal < 15 U/l), 26-33% of total AP (normal < 14%). Her other LFTs, TFT, PTH, Ca, CBC, BMP, GGT, viral hepatitis serologies, AMA and Vit D were unremarkable. Abdominal imaging revealed a fatty liver while a bone scan was normal. Our patient remained asymptomatic and did not require any treatment. DISCUSSION: Elevated AP can be physiological during rapid bone growth and pregnancy or pathological due to hepatobiliary disease or abnormal bone metabolism. Non-hepatic causes of elevated AP include heart failure, renal failure, hyperthyroidism, hyperparathyroidism and certain malignancies. IAP normally accounts for up to 14% of total AP. IAP can be elevated in conditions such as intestinal perforation, intestinal ischemia, extensive erosions/ulceration in GI tract, liver cirrhosis, familial benign elevation of IAP or post-prandial rise after a fatty meal particularly in patients with blood group B or O. Our patient did not have any of the above-listed conditions. Although she was blood group B, the blood draws were done after an overnight fast. While investigating elevated AP clinicians should be aware of pathological and benign causes of IAP elevation including benign intermittent IAP elevation which may require repeated testing of AP isozymes.