# US 11,079,397 B2 · Method and apparatus for determining a patient's filtration rate > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,079,397 B2 - Document ID: US11079397B2 - Status: Granted - Kind: B2 - Application number: 15/558,224 - Filed: 2016-03-24 - Published: 2018-03-22 - Granted: 2021-08-03 - Earliest claimed: 2015-03-24 - Assignees: Fresenius Medical Care Deutschland GmbH - Applicants: Fresenius Medical Care Deutschland GmbH - Inventors: Paul Chamney; Peter Wabel - Web page: https://patentgrep.com/patent/US11079397B2 ## CPC - G01N 33/70: involving creatine or creatinine - A61B 5/0531: Measuring skin impedance - A61B 5/0537: Measuring body composition by impedance, e.g. tissue hydration or fat content - A61P 7/10: Antioedematous agents; Diuretics - G01N 2800/347: Renal failures; Glomerular diseases; Tubulointerstitial diseases, e.g. nephritic syndrome, glomerulonephritis; Renovascular diseases, e.g. renal artery occlusion, nephropathy - G01N 2800/52: Predicting or monitoring the response to treatment, e.g. for selection of therapy based on assay results in personalised medicine; Prognosis - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) - A61P: SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS ## Abstract A method and an apparatus for determining or approximating a patient's glomerular filtration rate or a patient's creatinine clearance are disclosed. The method comprises the following steps: determining a serum creatinine concentration of the patient, determining a lean tissue mass of the patient, and determining the glomerular filtration rate of the patient or the creatinine clearance of the patient based on the serum creatinine concentration of the patient and the lean tissue mass of the patient. ## Claims ### Claim 1 Method for determining or approximating a patient's glomerular filtration rate or a patient's creatinine clearance in a patient undergoing intermittently a renal replacement treatment, the method comprising the steps of: determining a serum creatinine concentration of the patient, determining a lean tissue mass of the patient, determining the glomerular filtration rate of the patient or the creatinine clearance of the patient without using age or gender of the patient and based on the serum creatinine concentration of the patient and the lean tissue mass of the patient, determining which of chronic kidney disease (CKD) stages 1-5 the patient is in based on the determined glomerular filtration rate or creatinine clearance, and determining a criterion for applying a renal replacement therapy to the patient based on the determined glomerular filtration rate or creatinine clearance of the patient, wherein the step of determining the serum creatinine concentration includes determining a first serum creatinine concentration at a first time between treatment sessions and determining a second serum creatinine concentration at a second time between treatment sessions and wherein the step of determining the patient's glomerular filtration rate or creatinine clearance is based on the first creatinine concentration and on the second creatinine concentration. ### Claim 2 (depends on 1) Method according to claim 1, wherein the step of determining the lean tissue mass includes measuring the lean tissue mass. ### Claim 3 (depends on 2) Method according to claim 2, wherein the step of measuring the lean tissue mass includes applying a bioimpedance measurement. ### Claim 4 (depends on 1) Method according to claim 1, wherein the step of determining the serum creatinine concentration includes measuring the serum creatinine concentration from a blood sample of the patient. ### Claim 5 (depends on 1) Method according to claim 1, wherein the glomerular filtration rate Qgfr is determined by applying the formula: Q gfr = α ltm · M LT m β ts · [ Cr ] s , wherein MLTm is the lean tissue mass of the patient, [Cr]s is the serum creatinine concentration and αltm and βts are proportionality constants. ### Claim 6 (depends on 1) Method according to claim 1, further comprising the step of measuring the weight gain of the patient between the first time and the second time and wherein the step of determining the patient's glomerular filtration rate or creatinine clearance is based on the weight gain of the patient. ### Claim 7 (depends on 1) Method according to claim 1, further comprising the step of measuring a total body water of the patient by applying a bioimpedance measurement and wherein the step of determining the patient's glomerular filtration rate or creatinine clearance is based on the total body water of the patient. ### Claim 8 (depends on 1) Method according to claim 1, wherein the patient's glomerular filtration rate or creatinine clearance is determined at a plurality of times and wherein a timely average is determined of the patient's glomerular filtration rate or creatinine clearance and wherein an outlier is disregarded from the determination of the timely average. ### Claim 9 (depends on 1) Method according to claim 1, further comprising the step of determining a criterion for the prescription of a diuretic based on the determined glomerular filtration rate or creatinine clearance of the patient. ### Claim 10 Apparatus for determining or approximating a patient's glomerular filtration rate or a patient's creatinine clearance, the apparatus comprising: a first receiver configured to receive a serum creatinine concentration of the patient, a second receiver configured to include or connect to a measuring unit for measuring a lean tissue mass of the patient, and a central processing unit configured to determine (i) the glomerular filtration rate Qgfr of the patient by applying the formula Q gfr = α ltm · M LT m β ts · [ Cr ] s wherein MLTm is the lean tissue mass of the patient, [Cr]s is the serum creatinine concentration, and αltm and βts are proportionality constants, or (ii) the creatinine clearance of the patient by applying the formula K Cr_WB = α ltm · M LT_m [ Cr ] s wherein MLT_m is the lean tissue mass of the patient, [Cr]s is the serum creatinine concentration and αltm is a proportionality constant, without using age or gender of the patient. ### Claim 11 (depends on 10) Apparatus according to claim 10, wherein the measuring unit for measuring the lean tissue mass comprises a bioimpedance measuring unit. ### Claim 12 (depends on 10) Apparatus according to claim 10, wherein the central processing unit is configured to determine a criterion for the prescription of a diuretic based on the determined glomerular filtration rate or creatinine clearance of the patient. ### Claim 13 (depends on 10) Apparatus according to claim 10, wherein the central processing unit is configured to determine a criterion for applying a renal replacement therapy to the patient based on the determined glomerular filtration rate or creatinine clearance of the patient. ### Claim 14 (depends on 10) Apparatus according to claim 10, adapted for a patient undergoing a renal replacement therapy, wherein the first receiver is configured to receive a first serum creatinine concentration at a first time between treatment sessions and to receive a second serum creatinine concentration at a second time between treatment sessions and wherein the central processing unit is configured to determine the patient's glomerular filtration rate or creatinine clearance based on the first creatinine concentration and on the second creatinine concentration. ### Claim 15 (depends on 14) Apparatus according to claim 14, including a third determination unit for measurement of the weight gain of the patient between the first time and the second time and wherein the central processing unit is configured to determine the patient's glomerular filtration rate or creatinine clearance based on the weight gain of the patient. ### Claim 16 (depends on 14) Apparatus according to claim 14, including a bioimpedance measurement unit for measuring the total body water by applying a bioimpedance measurement of a patient and wherein the central processing unit is configured to determine the patient's glomerular filtration rate or creatinine clearance based on the total body water of the patient. ### Claim 17 (depends on 14) Apparatus according to claim 14, wherein each of a first and a second mode of operation is defined for the central processing unit and wherein the central processing unit is configured to determine the glomerular filtration rate Qgfr by applying the formula: Q gfr = α ltm · M LT m β ts · [ Cr ] s , wherein MLTm is the lean tissue mass of the patient, [Cr]s is the serum creatinine concentration, and αltm and βts are proportionality constants in the first mode of operation and wherein the central processing unit is configured to operate wherein the patient is undergoing intermittently a renal replacement therapy, and wherein the first receiver is configured to receive a first serum creatinine concentration at a first time between treatment sessions and to receive a second serum creatinine concentration at a second time between treatment sessions and wherein the central processing unit is configured to determine the patient's glomerular filtration rate or creatinine clearance based on the first creatinine concentration and on the second creatinine concentration in the second mode of operation. ### Claim 18 (depends on 1) Computer-readable non-transitory medium comprising instructions for the execution of a method according to claim 1 when the instructions are executed on a computer.