About L-FABP

FAQs

About L-FABP

Samples, measurement

RENISCHEM® L-FABP ELISA Kit

RENISCHEM® L-FABP POC Kit

Product performance/operation

RENISCHEM® L-FABP ELISA Kit

RENISCHEM® L-FABP POC Kit

Research use

About L-FABP

Q1. What is L-FABP?
A1. L-FABP is an abbreviation for “L-type Fatty Acid Binding Protein”, and is a low molecular weight soluble protein (14 kDa) that is specifically expressed in the liver and renal proximal tubules. Because L-FABP is a substance derived from the cytoplasm of the renal proximal tubules and is excreted in urine due to renal tubular ischemia and oxidative stress on renal tubules, urinary L-FABP is useful for early diagnosis of renal disease accompanying tubular dysfunction.
Q2. Is liver-derived L-FABP excreted in urine?
A2. L-FABP excreted from the liver is reabsorbed by the normal kidneys, so liver-derived L-FABP hardly appears at all in urine. On the other hand, liver-derived
L-FABP is no longer reabsorbed by the disordered kidneys, and is excreted in urine. In the case of fulminant hepatitis or hepatorenal syndrome, approximately 12% of urinary L-FABP originates in the liver, but liver-derived L-FABP can be easily discerned from kidney-derived L-FABP through joint use with other biomarkers.
Q3. How is L-FABP different from urinary albumin?

A3. Urinary albumin is a glomerular injury marker that indicates the result of filtration failure. The quantity excreted in the urine increases as the glomerular injury progresses. In contrast, L-FABP is a marker reflecting tubular dysfunction, and is excreted in the urine in response to ischemia and oxidative stress.

Q4. What is the clinical utility of L-FABP?

If you are interested in the clinical utility of L-FABP, please click here. Clinical Utilities

Samples, measurement

RENISCHEM® L-FABP ELISA Kit

Q1. Is it necessary to dilute samples before measurement?
A1. Dilution is not always required. For samples with L-FABP concentration in excess of 400 ng/mL, please dilute with a Standard Diluent (0 ng/mL), and then re-measure.
Q2. Is it necessary to adjust urinary L-FABP concentration with urinary creatinine correction?
What is the conversion formula for creatinine correction?
A2. In principle, urinary creatinine correction is necessary to prevent errors in urinary concentration. However, the values for urinary creatinine itself may fluctuate greatly in acute kidney injury (AKI). Therefore both of urinary L-FABP values with or without creatinine correction are reported to physicians, and doctors use their judgment as to whether to use actual values or creatinine corrected values.
Conversion Formula
L-FABP (ug/g・Cr) = L-FABP (ng/mL) ÷ Cr (mg/dL) × 100
Q3. When is the optimal time for taking urine samples for measurement?
A3. Urinary L-FABP can be measured in early morning urine, spot urine and pooled urine. However, it is desirable to prepare samples under the same conditions in monitoring L-FABP levels.
Q4. What are the methods for storing and stabilizing samples?
A4. Please store samples either by refrigeration (4 degrees Celsius) or freezing (-20 to -30 degrees Celsius, -80 degrees Celsius). Stability has been confirmed for up to 48 hours (2 days) when storing by refrigeration (4 degrees Celsius), and up to one (1) year when storing by freezing (-80 degrees Celsius). When storing samples by refrigeration, please make your measurements within 48 hours.
*If refrigeration is difficult, please use a coolant or similar.
Q5. Is there anything to be careful about in the freezing and thawing of samples?
A5. Thawing a sample saved by freezing (-80 degrees Celsius) and then taking measurements will have no effect on the measured values. However, please avoid repeated freezing and thawing.
*Where possible, storage after splitting samples into smaller portions is recommended. Also, samples may be cloudy after thawing, but measurement is still possible. Dispersing cloudiness in samples by centrifugal separation and then taking measurements will have no effect on the measured values.
Q6. Is there any influence on measurement when preservative is added to accumulated urine (samples)?
A6. Adding hydrochloric acid can sometimes have an effect (values tend to be lower than original L-FABP values) on measurements. The addition of sodium azide or toluene has no effect on measurements.
Q7. Are there diurnal rhythm variations in urinary L-FABP levels?
A7. Variations may be observed within the normal range of L-FABP levels.
Q8. Are there any effects on interference substances?
A8. Yes. Bilirubin, hemoglobin, glucose or ascorbic acid in sample can affect with the performance of ELISA Kit. However, the following levels can be present in the urine with no effect on measurement value:
1. Free bilirubin up to 19.7 mg/dL.
2. Conjugated bilirubin up to 21.8 mg/dL.
3. Hemolytic hemoglobin up to 24.4 mg/dL.
4. Glucose up to 45.0 mg/mL.
5. Ascorbic acid up to 12.5 mg/mL.
Q9. Does the contrast media for angiography have any effect on measurements?
A9. No. When the contrast media appears in urine, the baseline and measurement values of the urinary L-FABP are not affected by the contrast media. Urinary L-FABP is not affected by the contrast media itself. After angiography, urinary L-FABP is increased by renal microvascular flow reduction (cause by the renal vascular spasm) occurs due to the contrast media.

RENISCHEM® L-FABP POC Kit

Q1. Is it necessary to dilute samples before measurement?
A1. Dilution of samples is not needed.
Q2. When is the optimal time for taking urine samples for measurement?
A2. Urinary L-FABP can be measured in early morning urine, spot urine and pooled urine, except for acid pooled urine. However, it is desirable to prepare samples under the same conditions in monitoring L-FABP levels.
Q3. Which is the optimal sample condition for measurement?
A3. Urinary L-FABP can be measured fresh urine and stored urine in refrigerator and freezer.
Q4. How is urine sample stability at room temperature?
A4. Up to 8 hours at room temperature, we confirm the effect on measurement results should be minor. However, we recommend in the instruction for use that you measure urinary L-FABP immediately after urine collection especially in case that you measure high L-FABP concentration samples (such as a few hundred of L-FABP concentration (ng/mL)) as these high concentration samples rarely tend to increase the L-FABP values continuously.
Q5. Does the foreign substance in the sample have any effect on measurement systems?
A5. Yes. When the sample appears cloudy or contains the foreign substances such as red blood cells (bloody urine) and cell debris due to infectious diseases and inflammatory disorder, you are unable to take correct test results. Before you mix the sample with the Pre-treatment reagent, you should centrifuge the sample or stand the sample in the dark at room temperature for approximately more than 30 minutes. And then you can gently collect 100 μL of the supernatant as the sample.
Q6. Can viscous sample be measured?
A6. No. Even if you can take viscous sample using dropper, you could be unable to take correct test results due to clogging of viscous sample in the membrane and/or stagnating flow of the sample on the test strip. For these cases, we recommend that you measure urinary L-FABP in viscous sample using quantitative L-FABP Kit.
Q7. Are there any effects on interference substances?
A7. Yes. Bilirubin, hemoglobin, glucose or ascorbic acid in sample can affect with the performance of POC Kit. However, the following levels can be present in the urine with no effect on measurement value:
1. Free bilirubin up to 19.7 mg/dL.
2. Conjugated bilirubin up to 21.8 mg/dL.
3. Hemolytic hemoglobin up to 97.4 mg/dL.
4. Glucose up to 1000 mg/dL.
5. Ascorbic acid up to 1.6 mg/mL.
Q8. Can colored sample be measured?
A8. When the urine color is dark, you are unable to take correct test results.
Q9. Can the sample of patient with end stage renal failure (stage 4 of diabetic nephropathy or end stage kidney disease) be measured?
A9. Yes. Because previous report showed that urinary L-FABP levels were associated with the progression of diabetic nephropathy (stage 1 to 4), you can measure the sample of patient with end stage renal failure (Diabetes Care 34:691-696, 2011. PubMed▶).

Product performance/operation

RENISCHEM® L-FABP ELISA Kit

Q1. What are the details of Human L-FABP ELISA Kit?
A1. Human L-FABP ELISA Kit is quantitative assay of manual testing. This assay needs 96 well microplate reader for measuring absorbance.
Q2. What is measurement principle of ELISA method?
A2. You can browse from the following Measurement principle (ELISA method).
Q3. How is the component of the Human L-FABP ELISA Kit?
A3. You can browse from the following Product composition.
Q4. What is the recommended storage condition and shelf-life for Human
L-FABP ELISA Kit?
A4. Storage condition: between 2-8°C (avoid freezing)
Shelf-life: 24 months (expiry date is written on outer case)
Q5. Is it possible to obtain instruction for use?
A5. You can browse from the following Instruction.
Q6. How much does the product cost?
A6. About product cost, please Contact us.
Q7. Is this product returnable?
A7. We will not accept your return request due to the nature of product.

RENISCHEM® L-FABP POC Kit

Q1. What is RENISCHEM® L-FABP POC Kit?
A1. RENISCHEM® L-FABP POC Kit is semi-quantitative assay of manual testing. This assay is used at bedside without any reader devices.
Q2. What is the meaning of POC and the measurement principle?
A2. POC is an abbreviation for “Point of Care”, and can be performed at the bedside. This test is the rapid test which uses immunoadsorbent chromatography measurement method, similar to the flu kits. About measurement principle, you can browse from the following Measurement principle (POC).
Q3. What is the recommended storage condition and shelf-life for RENISCHEM® L-FABP POC Kit?
A3. Storage condition: between 1-30°C (avoid freezing)
Shelf-life: 18 months (expiry date is written on outer case)
Q4. Is it possible to obtain instruction for use?
A4. You can browse from the following Instruction.
Q5. Is there correlation between semi-quantitative POC Kit and quantitative ELISA Kit?
A5. High concordance rate over 90% is calculated from the measurement values of POC Kit and ELISA Kit.

Distribution chart of ELISA assay and POC results
Q6. What is product cost and distributor?
A6. About product cost and distributor, please Contact us.
Q7. Is this product returnable?
A7. We will not accept your return request due to the nature of product.

Research use

Q1. Are there any recommendations of renal injury markers to be compared with L-FABP?
A1. In case that you measure glomerular injury marker in combination with L-FABP as a tubular injury marker, the renal injury level can be evaluated.
Q2. Can we use human renal biopsy as the sample?
A2. If you collect the supernatant from appropriate amount of tissue homogenate, you can use the supernatant with pretreatment as the sample for ELISA Kit. However, we will not be able to guarantee the performance of our product because the original purpose of the product is to measure urinary L-FABP.
Q3. Can we measure blood L-FABP level?
A3. You can measure L-FABP level within the blood. However, we will not be able to guarantee the performance of our product because the original purpose of the product is to measure urinary L-FABP. In addition, we do not have information about the stability and the cut-off value of L-FABP in blood.

Download product leaflet

How to use RENISCHEM® L-FABP POC kit

For nonclinical safety evaluation

Urinary L-FABP kits for Rat, Dog, Cat, Monkey and Pig are available for the purpose of monitoring drug nephrotoxicity and drug effectiveness.
Top ▲ Home ▶