Urine Test Strips Show Promise and Limits in Rapid CSF Analysis

When a patient arrives with a suspected brain infection, hemorrhage, or inflammatory neurological disease, cerebrospinal fluid (CSF) drawn by lumbar puncture is often the decisive diagnostic sample. Yet full laboratory analysis of that fluid takes time, specialized equipment, and trained personnel, resources that are not always available when minutes matter. A new prospective study from Hannover Medical School in Germany, published in Frontiers in Neurology, examined whether simple, inexpensive urine test strips, the dipsticks familiar from routine urinalysis, could serve as a rapid bedside tool for CSF assessment, and the results reveal a strikingly uneven picture of what these strips can and cannot do.

The research team, led by Lina Marie Albers and Philipp Schwenkenbecher, analyzed 285 CSF samples from patients with a range of neurological diseases. Each sample was tested with urine test strips from five different manufacturers, allowing the investigators to compare strip results for leukocytes, erythrocytes, protein, and glucose both across brands and against standard laboratory measurements. The study then assessed how well the strips performed at three clinically meaningful tasks: detecting blood in the CSF, identifying pleocytosis, an elevated white cell count that signals inflammation, and helping to distinguish infectious from non-infectious neurological conditions.

The clearest success story involved blood detection. For identifying erythrocytes, red blood cells, in the CSF, the strips achieved sensitivity values between 86 and 95 percent, meaning they correctly flagged the vast majority of samples that actually contained blood. Just as importantly, the negative predictive value ranged from 92 to 97 percent, so when a strip came back negative for blood, that result was highly trustworthy.

The picture changed dramatically when the researchers turned to pleocytosis. Here the strips showed perfect specificity and a positive predictive value of 100 percent, meaning that whenever a strip did indicate elevated leukocytes, the sample truly was inflamed. But the sensitivity was only 11 percent, which means the strips missed nearly nine out of ten samples with genuine pleocytosis.

The underlying problem, the authors note, is that the strips systematically underestimated low leukocyte counts, precisely the range in which early or subtle inflammatory disease presents. A negative strip result for white cells therefore provides almost no reassurance that inflammation is absent. Protein detection showed variable performance across the sample set, without the consistent strengths or weaknesses seen for the cellular parameters.

Glucose and leukocyte readings, however, proved informative in a different way: when the goal was to differentiate infectious from non-infectious neurological conditions, both parameters demonstrated high specificity and high positive predictive value. In other words, abnormal strip findings pointing toward infection were usually correct, even though the strips again could not be relied upon to exclude infection when the results appeared normal. The investigators also tested whether combining parameters could improve diagnostic power.

Using a rule in which at least two of three positive findings among leukocytes, protein, and glucose counted as a positive overall result, the combined approach delivered consistently high specificity of 98 percent and a positive predictive value between 80 and 85 percent. The trade-off, however, was severe: sensitivity fell to just 13 to 15 percent, and the negative predictive value was only 63 percent. One practical question the study addressed directly was whether the choice of manufacturer mattered.

Across the five brands tested, no relevant differences in performance were observed, suggesting that the findings are not an artifact of a single product line and that clinicians in different settings could expect broadly similar behavior from commonly available strips. This cross-manufacturer consistency strengthens the generalizability of the results, which the authors note had previously been limited to evidence from single manufacturers. Taken together, the study positions urine test strips as a rapid, low-cost bedside adjunct rather than a replacement for standard laboratory diagnostics.

Their particular strength lies in reliably excluding blood contamination of the CSF, where high sensitivity and high negative predictive value make a negative strip result genuinely actionable. Their weakness lies in inflammation and infection, where low sensitivity undermines any attempt to rule disease out, even though positive findings are highly specific and should prompt immediate conventional workup. The authors conclude that urine test strips may support early bedside decision-making, particularly in time-critical situations or resource-limited settings where full laboratory CSF analysis is delayed or unavailable, but that they cannot substitute for thorough laboratory testing.

For clinicians, the message is one of calibrated expectations: the humble dipstick can quickly and cheaply answer one important question, whether blood is present in the spinal fluid, while leaving the far more consequential questions about infection and inflammation to the laboratory methods that remain indispensable for definitive diagnosis.

Subject of Research: Diagnostic accuracy of urine test strips for rapid bedside cerebrospinal fluid analysis

Article Title: Diagnostic accuracy of urine test strips for CSF analysis: high sensitivity in detecting blood, low sensitivity but high specificity in detecting inflammation

Article References: Albers, L. M., Konen, F. F., Atakan, E., Jendretzky, K. F., Nay, S., Grote-Levi, L., Sühs, K.-W., Skripuletz, T., & Schwenkenbecher, P. (2026). Diagnostic accuracy of urine test strips for CSF analysis: high sensitivity in detecting blood, low sensitivity but high specificity in detecting inflammation. Frontiers in Neurology, 17, Article 1893760. https://doi.org/10.3389/fneur.2026.1893760

Image Credits: AI Generated

DOI: 10.3389/fneur.2026.1893760

Keywords: cerebrospinal fluid, urine test strips, diagnostic accuracy, pleocytosis, erythrocytes, leukocytes, sensitivity and specificity, neuroinfectious diseases, bedside diagnostics, lumbar puncture, CSF analysis, point-of-care testing