Knowing your lab test well: Expanding the differential for elevated alkaline phosphatase

Abstract

Introduction: It is known that increased alkaline phosphatase with a distended gallbladder increases the suspicion of pancreatic malignancy. But benign etiology can be present, including a fasting state. Case Report: Our patient, a 58­year­old African–American female with a history of recurrent UTI presented to the emergency room with nausea and vomiting and loss of appetite for last five days. Physical exam was unremarkable except for dehydration. Initial laboratory test were normal including liver function tests, except for alkaline phosphatase level which was elevated to 216 (normal 35–120). She was started on intravenous fluids and antibiotics. Her symptoms improved and she tolerated a high protein and carbohydrate diet. She underwent an abdominal ultrasound of the right upper quadrant (2nd day of admission). It showed distended gallbladder and dilated common bile duct. No stones were seen and the liver was homogenous without masses. Gastroenterologist performed the EGD (3rd day of admission) which was benign. Her initial alkaline phosphatase trended down but started to rise again. The 5’ Nucleotidase was normal. An abdominal CT scan was performed (5th day of admission) showed no pancreatic mass, a contracted gallbladder and normal common bile duct. She was discharged home on oral antibiotics and a food supplement. Her follow up alkaline phosphatase was normal. Conclusion: Believe that our patient’s generalized weakness, weight loss, as well as her increased alkaline phosphatase, distended gallbladder and common bile duct dilation can be attributed to her fasting state. During this, alkaline phosphatase activity is increased. It is a component of regulatory mechanisms, by increased delivery of the enzyme to the blood and respective decrease and increase of the maximal velocities of the enzyme reactions. Studies done on rats and elephant seals showed that not only with fasting, but also with refeeding, alkaline phosphatase activity increases. Some studies have shown that fasting can cause phases of dilatation and phases of contraction of gallbladder which phases of maxima dilatation at 12 a.m. and 4 p.m., and maxima contraction at 8 a.m. and 4 p.m. Thus, we are inclined to conclude that starvation and refeeding have played role in our patient’s presentation timing is the key.