Reliable quantification of renal function from frozen blood samples

The study examined the possibility of measuring kidney function from long-term frozen blood samples, which is important for interpreting Alzheimer's disease biomarkers. The research included 134 adults aged 50-85 years with at least two vascular risk factors, of whom 23.1% had chronic kidney disease. Researchers compared creatinine measurements from rapid whole blood tests with measurements from frozen serum and plasma samples. Results showed very strong agreement between rapid tests and frozen samples (agreement coefficient 0.90-0.95). Pre-analytical factors had minimal impact on differences in kidney function measurements. The study conclusion confirms that kidney function can be reliably determined from frozen blood samples, which is useful for proper interpretation of Alzheimer's disease biomarkers in older people and patients with vascular problems.