How To Calculate Creatinine Clearance UK

UK MDRD or Cockcroft-Gault Adapted Formula:

\[ CrCl = \frac{(140 - Age) \times Weight \times 1.23}{SCr} \text{ (males)} \] \[ CrCl = \frac{(140 - Age) \times Weight \times 1.04}{SCr} \text{ (females)} \]

Age:

years

Weight:

Serum Creatinine (SCr):

μmol/L

Gender:

Creatinine Clearance (CrCl):

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1. What is Creatinine Clearance?

Creatinine clearance (CrCl) is a measure of kidney function that estimates the rate at which creatinine is cleared from the blood by the kidneys. The UK adapted formula combines elements from both MDRD and Cockcroft-Gault equations for clinical use in the United Kingdom.

2. How Does the Calculator Work?

The calculator uses the UK adapted formula:

\[ CrCl = \frac{(140 - Age) \times Weight \times 1.23}{SCr} \text{ (for males)} \] \[ CrCl = \frac{(140 - Age) \times Weight \times 1.04}{SCr} \text{ (for females)} \]

Where:

\( Age \) — Age in years
\( Weight \) — Body weight in kilograms
\( SCr \) — Serum creatinine in μmol/L
\( 1.23 \) — Male coefficient
\( 1.04 \) — Female coefficient

Explanation: This formula accounts for age-related decline in kidney function, body size, and gender differences in muscle mass and creatinine production.

3. Importance of CrCl Calculation

Details: Creatinine clearance is essential for assessing kidney function, guiding drug dosing (especially for renally excreted medications), and monitoring patients with kidney disease in UK clinical practice.

4. Using the Calculator

Tips: Enter age in years, weight in kg, serum creatinine in μmol/L, and select gender. Ensure all values are valid (age 1-120 years, weight > 0, SCr > 0).

5. Frequently Asked Questions (FAQ)

Q1: Why use the UK adapted formula?
A: The UK adapted formula combines the strengths of both MDRD and Cockcroft-Gault equations and is widely accepted in UK clinical practice for drug dosing and kidney function assessment.

Q2: What are normal CrCl values?
A: Normal CrCl is approximately 95-125 mL/min for young adults, decreasing with age. Values below 60 mL/min may indicate impaired kidney function.

Q3: When is this calculation most useful?
A: Particularly important for dosing medications that are renally excreted, such as antibiotics, antivirals, and some chemotherapeutic agents.

Q4: Are there limitations to this formula?
A: Less accurate in elderly patients, those with extreme body weights, muscle wasting conditions, or rapidly changing kidney function.

Q5: How does this differ from eGFR?
A: While both assess kidney function, CrCl is often preferred for drug dosing decisions, while eGFR is commonly used for CKD staging and diagnosis.