From the Guidelines
The most appropriate study for this patient is option E: No further evaluation is indicated. The patient presents with isolated indirect hyperbilirubinemia (total bilirubin 2.8 mg/dL with indirect bilirubin 2.6 mg/dL) with normal complete blood count, normal liver function tests, normal lactate dehydrogenase, and normal haptoglobin. These findings are consistent with Gilbert syndrome, a benign hereditary condition characterized by mild unconjugated hyperbilirubinemia due to reduced activity of the enzyme UDP-glucuronosyltransferase. Gilbert syndrome affects approximately 5-10% of the population and typically presents with mild jaundice during periods of stress, fasting, or illness (such as during this asthma exacerbation) 1. The normal hematologic parameters and absence of hemolysis markers rule out hemolytic causes, making options A, B, and C unnecessary. Abdominal ultrasonography (option D) would not be helpful since liver function tests are normal and the hyperbilirubinemia is indirect (unconjugated), indicating a pre-hepatic or hepatic processing issue rather than biliary obstruction. Gilbert syndrome requires no treatment or further evaluation as it has no clinical consequences beyond occasional mild jaundice. According to the American College of Radiology, in asymptomatic patients with mild laboratory abnormalities and intact hepatic function, a reasonable approach may include an initial evaluation for common hepatic diseases, with close clinical follow-up if the initial studies are unrevealing 1. In this case, the patient's presentation and laboratory results are consistent with Gilbert syndrome, and no further evaluation is necessary.
From the Research
Laboratory Findings
The patient's laboratory studies reveal an elevated serum indirect bilirubin level, with a total bilirubin of 2.8 and indirect bilirubin of 2.6. Other liver biochemical studies are normal, and serum lactate dehydrogenase and haptoglobin are also normal.
Possible Causes
Given the patient's elevated indirect bilirubin level and normal other liver biochemical studies, the possible causes of this condition include:
- Hemolytic anemia, which can be caused by various factors such as glucose-6-phosphate dehydrogenase (G6PD) deficiency, hereditary spherocytosis, or other enzymopathies.
- Gilbert syndrome, a mild genetic disorder that affects the liver's ability to process bilirubin.
Appropriate Studies
Based on the patient's laboratory findings and possible causes, the most appropriate study to order would be:
- A peripheral blood film, as it can help identify abnormalities in red blood cell morphology, such as spherocytes or Heinz bodies, which can be indicative of hemolytic anemia 2.
- Other studies, such as direct and indirect antiglobulin (Coombs) test, hemoglobin electrophoresis, or ultrasonography of the abdomen, may not be directly relevant to the patient's condition at this time.
Rationale
The patient's elevated indirect bilirubin level and normal other liver biochemical studies suggest a hemolytic process, and a peripheral blood film can help identify the underlying cause. The study by 3 highlights the importance of searching for additional erythrocyte hereditary diseases in patients with G6PD deficiency, and a peripheral blood film can be a useful tool in this regard. Additionally, the study by 4 illustrates the importance of clinico-pathological correlation and judicious extended testing for various contributing factors that may modify the clinical course of patients with hereditary spherocytosis.
Further Evaluation
Further evaluation may include testing for G6PD deficiency, as it is a common cause of hemolytic anemia, especially in patients with elevated indirect bilirubin levels 5. However, at this time, a peripheral blood film is the most appropriate initial study to order.