["Occult" renal insufficiency due to evaluating renal function using only serum creatinine].

Area of Science:

• Nephrology
• Clinical Chemistry

Background:

• Accurate assessment of renal function is crucial for timely referral to nephrologists.
• Serum creatinine is the standard but has limitations in reflecting true glomerular filtration rate (GFR).
• Creatinine clearance via 24-hour urine collection is cumbersome and prone to errors.

Purpose of the Study:

• To compare the accuracy of serum creatinine and the Cockcroft-Gault (C-G) equation in estimating GFR.
• To identify patients with reduced GFR despite normal serum creatinine levels.

Main Methods:

• A study of 1,053 outpatients with serum creatinine < 2.5 mg/dl.
• GFR was determined using the Cockcroft-Gault formula.
• Patients were categorized by serum creatinine levels: normal (< 1.3 mg/dl) and "incipient" abnormal (1.3-2.5 mg/dl).

Main Results:

• Significant GFR reduction (< 50 ml/min) was observed in older females and males with normal serum creatinine.
• A substantial proportion of patients with "incipient" renal failure (serum creatinine 1.3-2.5 mg/dl) exhibited severe renal insufficiency (GFR < 30 ml/min).
• Prevalence of reduced GFR increased with age in both sexes, particularly in females.

Conclusions:

• Serum creatinine alone is insufficient for accurately assessing renal function, especially in elderly populations.
• The Cockcroft-Gault equation is a more reliable tool for estimating GFR and detecting early renal impairment.
• Emphasizing alternative renal function measurements beyond serum creatinine is vital for improved patient management and prevention of kidney disease progression.