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New Formula for Assessing Kidney Function with Age

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Within the framework of a Berlin cohort study, scientists from Charité – Universitätsmedizin Berlin have succeeded in developing new mathematical formulas that dependently assess kidney function with age. The kidney function of 600 participants 70 years and older were measured in several blood samples with the help of small amounts of contrast agents. Based on the results, two new formulas were developed that provide more exact estimates than other standard formulas. The study has been published in the current issue of Annals of Internal Medicine*.

The ability of kidneys to free the blood from toxins slowly decreases with increasing age. This gradual reduction in kidney function is fundamentally normal, must however, be taken seriously. For example, medication doses must be adjusted and the administration of x-ray contrast agents must be reassessed. Furthermore, reliable information about kidney function is decisive for determining when a patient must begin dialysis (blood washing), or in deciding to be a living donor for kidney transplantation. As a result of the population’s increasing age, more and more people are affected by a reduction of kidney function. Thus the correct assessment of kidney performance is of great relevance.

In daily clinic life, kidney function is estimated with the help of mathematical formulas. This is usually done by calculating the patient’s age, gender, and the concentration of a particular metabolic product: creatinine. Creatinine is filtered out through urine, is however a very sensitive indicating marker especially with age. That is why formulas that only take into consideration the concentration of creatinine are not always reliable for older people. “Besides creatinine, the formula applied in the current study also includes blood values from the protein cystatin C which appears to be more appropriate than creatinine for assessing kidney function, especially with age,” states Dr. Elke Schaeffner, primary author of the study and physician at the Department of Nephrology and Internal Intensive Care Medicine at Charité.

* Elke S. Schaeffner et al: Two Novel Equations to Estimate Kidney Function in Persons Aged 70 Years or Older. In: Annals of Internal Medicine, Volume 157, Issue 7, 471-481.


Article in Annals of Internal Medicine


PD Dr. Elke Schaeffner
Medizinische Klinik mit Schwerpunkt Nephrologie und Internistische Intensivmedizin
Campus Virchow-Klinikum
t: +49 03 450 553 131

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