Device and method for obtaining clinically significant analyte ratios

• US 6,436,721 B1
• Filed: 07/25/1997
• Issued: 08/20/2002
• Est. Priority Date: 07/25/1997
• Status: Expired due to Term

• Current Assignee: Siemens Healthcare Diagnostics Incorporated (Siemens AG)
• Original Assignee: Bayer Corporation (Bayer AG)
• Inventors: Zimmerle, Chris T., Miller, Carol A., Wijesuriya, Dayaweera, Kuo, Hai-Hang, Yip, Meitak Teresa
• Primary Examiner(s): Swartz, Rodney P
• Application Number:
  US08/900,586
• Time in Patent Office: 1,852 Days
• Field of Search: 435/7.1, 435/973, 436/98, 436/514, 436/518, 436/534, 436/909
• US Class Current: 436/514
• CPC Class Codes: G01N 33/54388 based on lateral flow
• CPC Class Codes: G01N 33/558 using diffusion or migration of antigen or antibody immunochromatographic test strips G01N33/54387
• CPC Class Codes: Y10S 435/973 Simultaneous determination of more than one analyte
• CPC Class Codes: Y10S 436/909 Nephelometry
• CPC Class Codes: Y10T 436/147777 Plural nitrogen in the same ring [e.g., barbituates, creatinine, etc.]

Abstract

Disclosed is a method for determining the concentration of an analyte in a sample of body fluid. The method involves contacting the body fluid sample with a test strip containing mobile, labeled specific binding partner for the analyte, through which strip the test fluid, analyte and any complex formed by interaction of the analyte and labeled specific binding partner therefore can flow by capillarity. The strip contains at least one zone for capture of the labeled specific binding partner and at least one separate zone for retention of the analyte/labeled specific binding partner complex. By determining the magnitude of the signal from the detectable label in the capture zone(s) and retention zone(s) and determining a final response signal by correlating signals using an algorithm and number of zones chosen in a manner that provides a final response signal best suited for the particular assay, the concentration of the analyte can be determined with greater precision.

Claims

1. A method for determining the concentration of an analyte in a sample of body fluid which comprises the steps of:

a) providing a test matrix in the form of a strip through which the fluid sample can flow by capillarity, said strip having a first region which contains mobile specific binding partner for the analyte which binding partner bears a visually detectable label and can react with the analyte to form an analyte/labeled binding partner complex, at least one second region which contains immobilized analyte or an immobilized binding partner which is specific for an epitope of the analyte different than that to which the labeled binding partner is specific, at least one third region which contains means for capturing the analyte/labeled specific binding partner complex which is not bound in the second region and a fourth region which contains means for calorimetrically producing a visually detectable signal the intensity of which corresponds to the level of a second analyte in the sample of body fluid whose concentration is clinically related to that of the first analyte whose concentration is being determined;

b) developing the matrix by applying a sample of a body fluid suspected of containing the first and second analytes thereto thereby allowing it to contact the labeled specific binding partner so that analyte present in the fluid sample binds to the labeled specific binding partner to form a complex while leaving excess, unreacted labeled binding partner free to further react whereby the fluid sample carries the analyte/labeled binding partner complex and unreacted labeled binding partner along the matrix by capillarity to the second region containing the immobilized analyte in which region unreacted labeled binding partner is bound to the immobilized analyte in inverse relationship to the concentration of the first analyte in the fluid tests sample or the analyte/labeled specific binding partner complex is bound to the immobilized specific binding partner in a direct relationship to the concentration of first analyte in the fluid test sample; and

the labeled specific binding partner which did not bind to the second region is carried by capillarity to the third region where it is immobilized by the immobilization means;

c) reading the second region of the developed matrix on a reflectance meter having a detector capable of measuring the visible signal from the visually detectable label to determine the concentration of the visually labeled binding partner in the second zone and reading the third zone of the developed strip in a similar manner to determine a signal from the labeled binding partner in the third zone of the matrix;

d) determining the final response signal by ratioing the signals from the labeled binding partner captured in the second region and the labeled binding partner immobilized in the third region;

e) determining the concentration of the first analyte in the fluid sample by comparing the final response signal determined in step d with final response signals determined in a similar manner for fluid samples containing known concentrations of the first analyte; and

f) correcting the concentration of the first analyte as determined in step e by determining the concentration of the second analyte in the fluid test sample by measuring the intensity of the signal in the fourth region of the strip using a reflectance meter and then determining the ratio of the second analyte to the first analyte whose quantitative concentration is being sought.

2. The method of claim 1 wherein the body fluid is urine, whole blood, plasma, serum, sweat or saliva.

3. The method of claim 2 wherein the body fluid is whole blood, the first analyte is HbA_1c and the second analyte is total hemoglobin.

4. The method of claim 2 wherein the body fluid is serum, the first analyte is transferrin and the second analyte is transferrin-iron binding capacity.

5. The method of claim 2 wherein the body fluid is urine, the first analyte is a urine born substance and the second analyte is a material whose concentration is a measure of renal clearance.

6. The method of claim 5 wherein the second analyte is creatinine or inulin.

7. The method of claim 6 wherein the first analyte is deoxypyridinoline, human serum albumin, amphetamines, barbituates, cocaine, prostate specific antigen, lactate dehydrogenase, N-acetyl-B-D-glucosamindase, human chorionic gonadotropin, follicle stimulating hormone, lutenizing hormone, Tamm-Horsfall protein, lipopolysaccharide, beta-2-microglobulin, amylase and chlamydial LPS.

8. The method of claim 2 wherein the body fluid is whole blood or serum, the first analyte is total prostate specific antigen and the second analyte is free prostate specific antigen.

9. The method of claim 1 wherein the first analyte is alanine aminotransferase and the second analyte is aspartate aminotransferase.

10. The method of claim 1 wherein the matrix is in the form of a strip through which the fluid sample flows horizontally.

11. The method of claim 1 wherein the second region of the test matrix is divided into 3 discrete bands, the third region is a single band and the final response signal is determined by solving the equation:

12. The method of claim 1 wherein the second and third regions of the test matrix are divided into multiple capture and detection bands respectively and the final response signal is determined by solving the equation:

13. The method of claim 1 wherein the strip is read by use of a reflectance meter which is equipped with software which is pre-programmed with the appropriate algorithm for the determination of the final response signal from reflectance signals received from the first and second regions and for the determination of the concentration of the second analyte from the reflectance signal received from the fourth region and for the determination of the ratio of the concentration of the second analyte in the sample of body fluid to the concentration of the first analyte to determine the corrected concentration of the first analyte.