What is the eGFR of a 73-year-old male with a weight of 64 kg and serum creatinine of 1.1 mg/dL?

Calculation of eGFR for a 73-year-old Indian Male

For a 73-year-old Indian male weighing 64 kg with serum creatinine of 1.1 mg/dL, the estimated glomerular filtration rate (eGFR) using the Cockcroft-Gault equation is 54.5 mL/min.

Calculation Method

The most appropriate formula to use for this patient is the Cockcroft-Gault equation, which is widely recommended for drug dosing purposes and takes into account age, weight, gender, and serum creatinine 1.

Cockcroft-Gault Formula:

CrCl (mL/min) = [(140 - age) × weight (kg) × (0.85 if female)] / [72 × serum creatinine (mg/dL)]

For this 73-year-old male patient:

CrCl = [(140 - 73) × 64] / [72 × 1.1]
CrCl = [67 × 64] / 79.2
CrCl = 4288 / 79.2
CrCl = 54.5 mL/min

Alternative eGFR Calculation Methods

While Cockcroft-Gault is preferred for drug dosing, other formulas could be considered:

MDRD (Modification of Diet in Renal Disease) Formula:

eGFR (mL/min/1.73m²) = 186 × [serum creatinine (mg/dL)]^-1.154 × [age (years)]^-0.203 × [0.742 if female] × [1.212 if Black]

For Indian ethnicity, no specific multiplier is established in most guidelines 1.

CKD-EPI Formula:

This newer equation may provide more accurate estimates, especially at higher GFR values 2.

Clinical Implications

With an eGFR of 54.5 mL/min, this patient falls into Stage 3a CKD (eGFR 45-59 mL/min/1.73m²) according to the KDIGO classification 1, 3. This represents a mild to moderate decrease in kidney function.

Important considerations:

• This level of kidney function requires monitoring every 3-6 months 3
• Medication dosages may need adjustment for drugs cleared by the kidneys 1
• Screening for albuminuria is necessary to complete CKD staging 1, 3
• Blood pressure control is essential, with target <130/80 mmHg 3

Potential Limitations

Several factors may affect the accuracy of eGFR calculations:

• The Cockcroft-Gault formula may be less accurate in elderly patients 1
• Different laboratory methods for measuring serum creatinine can affect results 1
• Muscle mass variations can influence serum creatinine levels independent of kidney function 4
• For drug dosing purposes, Cockcroft-Gault remains preferred over MDRD 5

Conclusion

The patient's eGFR of 54.5 mL/min using the Cockcroft-Gault formula indicates Stage 3a CKD. This requires regular monitoring of kidney function and appropriate medication adjustments. For comprehensive assessment, albuminuria testing should be performed to complete CKD staging.