Interference of fluorescein with creatinine assays

Systemic reaction to and interference with urine protein measurements after intravenous fluorescein injection

Background

Fluorescein angiography is an important and frequently used diagnostic tool in ophthalmological practice. In this case report we describe a patient who experienced an anaphylactic reaction after the injection of fluorescein. Furthermore, we report an interference with laboratory testing by fluorescein in this patient and summarize the literature on this topic.

Case presentation

An 86-year old Caucasian woman undergoing fluorescein angiography due to suspected peripapillary neovascularizations collapsed after the injection of fluorescein. The patient developed an anaphylactic reaction. With fluid resuscitation and oxygen therapy, the patient regained consciousness after a few minutes. The patient was admitted to the geriatric ward for observation, and routine blood and urine tests were performed. Urine protein concentration appeared to be falsely increased as a consequence of disturbance of the laboratory analysis by the presence of fluorescein.

Conclusions

Serious complications can occur with fluorescein angiography, such as an anaphylactic reaction. In the case of anaphylaxis appropriate supportive measures including the use of oxygen and epinephrine (e.g. EpiPen), should be available to prevent morbidity and mortality from this test. Furthermore, these potential complications should be taken into consideration when choosing the healthcare setting for fluorescein angiography, such as the immediate availability of an acute medical team.

Several studies have demonstrated the interference of laboratory analyses by fluorescein. The majority of these studies were published 10 to 30 years ago. By presenting this case, the authors hope to bring renewed attention to this phenomenon among clinicians, as falsely increased or decreased laboratory values can result in unnecessary diagnostics and/or therapy.

Biochemical evaluation of kidney disease

Different biochemical markers exist in both blood and urine for assessing renal function. Most of these biomarkers have advantages and limitations associated with their use, which is important to consider when ordering and utilising them in the clinical setting. The ideal marker should be able to detect acute kidney injury (AKI) at the onset and be used for the diagnosis and ongoing monitoring and management of kidney disease. The search for such a marker is ongoing, as all potential candidates thus far are associated with certain limitations. This article will attempt to compare and contrast established and emerging kidney disease markers.