gms | German Medical Science

Background: Immunocompromised patients are at risk for invasive fungal infections (IFI) like invasive pulmonary aspergillosis. Invasive diagnostic procedures are difficult to perform in hematologic patients because of contraindications like cytopenia or coagulation disorders. Determination of serum galactomannan (GM) levels has been found to be a valid surrogate parameter for early detection of IFI. However, various clinical factors may influence serum GM levels.

Clinical case: A 68-year old male patient suffering from angioimmunoblastic T cell lymphoma was admitted for high-dose chemotherapy with consecutive autologous hematopoetic stem cell transplantation. On admission, the patient was well and free of symptoms. Initial laboratory tests did not show any significant abnormalities. A high-dose chemotherapy regimen (containing rituximab, thiotepa, etoposide, cytarabine, and melphalane – R-TEAM) was administered and autologous stem cells were retransfused without any problems. Consecutively, the patient developed severe mucositis, presenting as persisting diarrhea (CTC-grade 3) and reduced appetite during the treatment-induced neutropenic phase. Simultaneously with the onset of neutropenia (day 1 after stem cell transplantation), an increase of C-reactive protein was documented. Due to a moderate weight loss he consumed several energy drinks per day as nutritional supplements. On day 6 after retransfusion a routinely performed serum test showed a GM level of 1.5 (indicated as index, cut off 0.5). Due to this finding a lung CT scan was performed which showed no signs of invasive pulmonary aspergillosis. Similarly, an ultrasound examination did not show any abnormalities. Still, because of persistent neutropenia a calculated antifungal therapy was initiated. However, during the course of neutropenia and after engraftment the GM levels increased gradually up to 2.1 without any signs of IFI. On closer examination, the list of ingredients of the energy drinks indicated ‘galacto-oligosaccharides’ and the standard test for galactomannan showed a high positive result in the drink. Hence, the patient was advised to stop consuming these drinks and a couple of days later the GM level decreased to 1.1 and eventually normalised. We assumed a disturbed intestinal mucosal barrier because of the treatment-induced diarrhea leading to false positive GM results. In order to test our hypothesis, two healthy subjects consumed the same energy drinks and serum GM levels were determined prior to and 6 hours after ingestion. No increase in serum GM could be detected.

Conclusion: This case report indicates a potential source of false positive results for serum GM tests. High caloric drinks can be an important support in the diet of hematologic patients. A disturbed intestinal mucosal barrier may lead to the transfer of ingested sugar-molecules into the patients’ blood and thereby affect serum GM levels.