Renal Iohexol Clearance Survey - RENIS

Age-related decline in kidney function is a leading cause of chronic kidney disease (CKD). More than one-third of individuals over 60 develop CKD. It is anticipated that CKD will become one of the leading global health challenges by 2040. This project is based on the Renal Iohexol Clearance Survey (RENIS), the only longitudinal study worldwide that accurately measures kidney function in a representative population sample. Approximately 1,800 participants have had their kidney function—measured as glomerular filtration rate (GFR)—assessed multiple times over a 15-year period.

We investigate the causes of age-related decline in glomerular filtration rate (GFR), the reasons many people develop chronic kidney disease (CKD), sex differences in GFR decline, and the impact of GFR loss on overall health in older adults.

Sub-projects include studies on lifestyle-related factors such as diet, physical activity, and obesity, along with biomarkers, in relation to GFR loss and the development of CKD and cardiorenal metabolic (CRM) syndrome. The study also examines the impact of GFR decline on the onset of frailty, cognitive impairment, lung disease, cancer, and mortality.

In collaboration with European partners, we have developed a new method for more accurate estimation of GFR, which has been published in the Annals of Internal Medicine and the New England Journal of Medicine. This method, which performs particularly well in both younger and older patients, is now being implemented in Norway and several European countries as a new standard. https://ekfccalculator.pages.dev/

We aim to redefine CKD by incorporating age-specific criteria to minimize overdiagnosis in older adults and underdiagnosis in younger individuals.

The project is expected to contribute valuable knowledge to help prevent the emerging CKD epidemic in aging populations. The results will be important for identifying individuals at high risk of CKD, facilitating early preventive interventions. This could decrease morbidity and the need for dialysis or kidney transplantation. More accurate GFR estimation may also minimize medication dosing errors and inappropriate treatment, which helps to lower healthcare costs.