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The Importance of Correct Protein Concentration for Kinetics and Affinity Determination in Structure-function Analysis
Published on: March 17, 2010
Plasma cystatin C determinations in a healthy elderly population
H Finney1, C J Bates, C P Price
1Department of Clinical Biochemistry, St Bartholomew's and the Royal London School of Medicine and Dentistry, Turner Street, London E1 2AD, UK. h.finney@mds.qmw.ac.uk <h.finney@mds.qmw.ac.uk>
Archives of Gerontology and Geriatrics
|September 18, 2004
Summary
Plasma cystatin C is a better indicator of kidney function than creatinine in older adults. This study established new reference ranges for cystatin C and creatinine, showing decreased kidney function with age.
Area of Science:
- Gerontology
- Nephrology
- Clinical Chemistry
Background:
- Plasma cystatin C is a more sensitive marker of glomerular filtration rate (GFR) changes than plasma creatinine.
- Existing reference intervals for cystatin C are limited to pediatric and adult populations up to 60 years.
- There is a need to establish reference ranges for cystatin C in the elderly population.
Purpose of the Study:
- To determine elderly reference ranges for plasma cystatin C and creatinine.
- To assess the relationship between age, gender, and GFR in individuals over 65 years.
- To evaluate cystatin C as a marker for age-related decline in kidney function.
Main Methods:
- Blood samples were collected from 401 subjects aged 65-101 years.
- Plasma cystatin C and creatinine concentrations were measured using commercial assays.
- Predicted creatinine clearance was calculated using the Cockcroft and Gault formulae.
Main Results:
- Plasma cystatin C concentrations increased with age (1.39 mg/l for 60-79 years, 1.70 mg/l for >80 years) but showed no significant gender difference.
- Plasma creatinine showed a significant gender difference (female, 99 micromol/l; male, 120 micromol/l) but not between age groups.
- Predicted GFR significantly decreased by 20% per decade, with established age- and sex-related reference intervals for creatinine, cystatin C, and predicted creatinine clearance.
Conclusions:
- Plasma cystatin C is a sensitive screening assay for early GFR changes in the elderly.
- Age-related decline in GFR is reflected by increasing cystatin C levels.
- New reference intervals for cystatin C and creatinine in the elderly population were established.
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