Related Experiment Video

Updated: Jul 19, 2026

The Importance of Correct Protein Concentration for Kinetics and Affinity Determination in Structure-function Analysis
19:16

The Importance of Correct Protein Concentration for Kinetics and Affinity Determination in Structure-function Analysis

Published on: March 17, 2010

GFR estimation using cystatin C is not independent of body composition

Jamie Macdonald1, Samuele Marcora, Mahdi Jibani

  • 1School of Sport, Health and Exercise Sciences, University of Wales-Bangor, Gwynedd, LL57 2PZ, UK. j.h.macdonald@bangor.ac.uk

American Journal of Kidney Diseases : the Official Journal of the National Kidney Foundation
|October 25, 2006
PubMed

Insights

Lean mass significantly impacts cystatin C levels, a marker for kidney function. Including lean mass in equations improves glomerular filtration rate (GFR) estimation, challenging the assumption that cystatin C is independent of body composition.

Area of Science:

  • Nephrology
  • Biochemistry
  • Clinical Chemistry

Background:

  • Cystatin C (CysC) is an endogenous marker used to estimate glomerular filtration rate (GFR).
  • It has been widely assumed that CysC levels are independent of body composition.
  • This study investigates the influence of body composition on CysC levels and GFR estimation.

Purpose of the Study:

  • To test the assumption that cystatin C (CysC) is unaffected by body composition.
  • To evaluate the impact of lean mass (LM) on CysC levels and GFR estimation.
  • To develop and compare GFR prediction equations based on CysC alone versus CysC with LM.

Main Methods:

  • In 77 chronic kidney disease patients, GFR was measured using inulin clearance.
  • CysC levels were quantified using a particle-enhanced turbidimetric immunoassay.
  • Dual-energy x-ray absorptiometry measured total lean mass (LM) and fat mass. Multiple regression analysis explored relationships between GFR, body composition, and CysC.

Main Results:

  • Both absolute GFR and LM were significant predictors of CysC levels.
  • An equation incorporating LM explained more GFR variance than one using CysC alone.
  • The LM-inclusive equation demonstrated superior performance, especially in patients with extreme body composition, showing improved accuracy (71.4% vs. 51.4% within 30% of true GFR).

Conclusions:

  • Lean mass (LM) is a significant, previously unrecognized factor influencing cystatin C (CysC) levels.
  • Incorporating LM into GFR estimation equations improves accuracy.
  • CysC is not independent of body composition, and accounting for it enhances GFR estimation accuracy.
Abstract

More Related Videos

Segmentation and Linear Measurement for Body Composition Analysis using Slice-O-Matic and Horos13:35

Segmentation and Linear Measurement for Body Composition Analysis using Slice-O-Matic and Horos

Published on: March 21, 2021

Related Concept Videos

Drug Dosing in Renal Diseases: Estimation of Glomerular Filtration Rate Based on Serum Creatinine Concentration01:28

Drug Dosing in Renal Diseases: Estimation of Glomerular Filtration Rate Based on Serum Creatinine Concentration

Glomerular filtration rate (GFR) can be estimated from serum creatinine using the modification of diet in renal disease (MDRD) formula or the chronic kidney disease–epidemiology collaboration (CKD–EPI) equation. Both methods are widely used in clinical practice to assess kidney function and guide treatment decisions.The MDRD equation does not require weight or height measurements and is normalized to the body surface area of 1.73 m², considered the average adult surface area. This equation is...
Drug Dosing in Renal Diseases: Measurement of Glomerular Filtration Rate01:25

Drug Dosing in Renal Diseases: Measurement of Glomerular Filtration Rate

The glomerular filtration rate (GFR) is a critical indicator of kidney health, reflecting how well the kidneys filter blood. Changes in GFR can signal potential kidney impairment, necessitating accurate measurement methods to monitor kidney function effectively.Various molecules can serve as markers for GFR measurement, with the ideal marker meeting several specific criteria. It must freely filter at the glomerulus, avoid reabsorption or secretion by the renal tubules, remain unmetabolized, not...
Drug Dosing in Renal Diseases: Measurement of Serum Creatinine Concentration and Clearance01:25

Drug Dosing in Renal Diseases: Measurement of Serum Creatinine Concentration and Clearance

In healthy individuals, serum creatinine levels remain stable due to a balance between its constant production—primarily from muscle metabolism—and renal excretion. Creatinine is freely filtered by the glomeruli, making it a valuable marker for estimating renal function. When the glomerular filtration rate (GFR) decreases, the kidneys can only eliminate less creatinine, causing serum levels to rise.Serum creatinine concentration is widely used to estimate creatinine clearance (Clcr), a...
Renal Clearance01:23

Renal Clearance

The glomerular filtration rate (GFR) is a critical marker of kidney function, reflecting the efficiency of filtration by the glomeruli. Renal clearance of specific substances, such as inulin or creatinine, is commonly used to measure GFR.
Renal clearance refers to the volume of plasma cleared of a specific substance, such as creatinine, per unit of time. To measure clearance, urine samples are collected over a 24-hour period during each bladder voiding, followed by a single blood sample at the...
Serum Studies: Renal Function Tests01:24

Serum Studies: Renal Function Tests

Renal function tests are crucial for assessing kidney health, monitoring disease progression, and evaluating the kidneys' efficiency in waste elimination, fluid balance, and electrolyte regulation. These tests offer critical insights into kidney function, even though routine measurements may appear normal until there is a significant decline in the glomerular filtration rate or GFR. Typically, signs of kidney impairment only become evident when the GFR falls to about 50% of its normal level.
Factors Affecting Renal Clearance: Renal Impairment01:17

Factors Affecting Renal Clearance: Renal Impairment

Renal dysfunction significantly impairs the renal clearance of drugs, leading to potential complications in drug therapy. Renal failure, which can be caused by various factors, poses a significant challenge in the elimination of drugs from the body.
One condition associated with renal failure is uremia. Uremia is characterized by impaired glomerular filtration and fluid accumulation in the body. This condition hinders the renal clearance of drugs, resulting in drug accumulation and potential...