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Clearance Formula:
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Clearance calculation measures the renal clearance rate, which represents the volume of plasma completely cleared of a substance per unit time. It's a fundamental concept in pharmacokinetics and renal physiology.
The calculator uses the clearance formula:
Where:
Explanation: This formula calculates the renal clearance rate by determining how efficiently the kidneys remove a substance from the blood plasma.
Details: Clearance calculations are essential for assessing kidney function, determining drug elimination rates, and understanding substance handling by the kidneys. It helps in diagnosing renal impairment and adjusting medication dosages.
Tips: Enter urine concentration in mg/mL, urine flow rate in mL/min, and plasma concentration in mg/mL. All values must be positive numbers greater than zero for accurate calculation.
Q1: What is the clinical significance of clearance?
A: Clearance indicates how efficiently the kidneys remove waste products and drugs from the body, helping assess renal function and guide medication dosing.
Q2: What are normal clearance values?
A: Normal creatinine clearance is approximately 95-125 mL/min for women and 110-150 mL/min for men, but varies with age, body size, and the substance being measured.
Q3: When should clearance be measured?
A: Clearance measurements are used when assessing kidney function, evaluating drug elimination, monitoring renal disease progression, or adjusting nephrotoxic medications.
Q4: What factors affect clearance rates?
A: Age, gender, body surface area, renal blood flow, protein binding, and the specific characteristics of the substance being cleared all influence clearance rates.
Q5: How does clearance differ from GFR?
A: GFR measures filtration rate, while clearance measures the removal rate of specific substances. For substances that are freely filtered and not reabsorbed or secreted, clearance equals GFR.