How much was previously known about the predictors of kidney failure?
Diabetes, hypertension and other cardiovascular diseases as well as obesity are some of the markers of risk for kidney failure that we are aware of in adulthood.
Markers of risk prior to adulthood for subsequent chronic kidney disease resulting in kidney failure are less well described.
The majority of individuals that suffer from kidney failure lose their kidney function in a gradual process spanning over decades. To be able to study these processes in a long-term or in other words in a life-course perspective is a practical challenge for researchers.
The wealth of high quality health registers maintained by state agencies in Sweden offer unique opportunities to address these difficulties.
Please can you outline your recent study that focussed on kidney failure and measurements taken in adolescence?
The study was based on Swedish male residents who had a physical examination at the time they were compulsorily enlisted in the military in the early 1970s; when the majority of these individuals were 18 and 19 years old.
Up to the age of 58 years, we identified 534 men who developed End Stage Renal Disease (ESRD) and compared them to a similar group of 5127 men who did not develop ESRD.
What were the main findings of this study?
The presence of proteinuria (protein in urine) in adolescence was associated with a seven-fold increase in the risk of ESRD.
Low-grade inflammation found by testing for the erythrocyte sedimentation rate in blood indicated a two-fold increase in kidney failure risk.
Hypertension, defined as BP>160/100 and higher, quadrupled the risk of developing ESRD, while a Body Mass Index (BMI) of 30 or above (indicating obesity) increased the ESRD risk by 3.5 times.
Were you surprised by the magnitude of the risk found?
Yes, we were surprised by the magnitude of the risk, especially for individuals with unexplained proteinuria in adolescence.
Why was this research only carried out on Swedish male residents and do you think the findings would be relevant to females and populations in other countries?
The baseline examination was based on conscription for military service which at that time was limited almost exclusively to men in Sweden.
Although the study was limited to men, there is no biological reason we can imagine for these findings not being relevant to populations in other industrialized countries.
What is causing silent kidney damage in some teenagers?
There are many theories but no conclusive answers to this question. Which events trigger the low-grade inflammation that we see in some of these teens and how early in life does this start? These are fascinating questions that inspire further research.
What can be done to stop kidney damage in teenagers and later kidney disease?
It is important to establish a healthy lifestyle in childhood and adolescence; and then to maintain it throughout adult life.
Unhealthy weight gain or an elevated blood pressure in adolescence should be taken seriously as addressing these problems at a later age may be more difficult.
Unexplained proteinuria should be followed-up to identify ongoing kidney damage. Overall the results suggest that there is a screening opportunity at an early age if we want to prevent chronic kidney disease.
What are your future research plans?
We are now looking at early life exposures to identify possible pathways and mechanism to explain the raised risks we have seen. The possible influence on the immune system and inflammatory mechanisms from infections in childhood and adult life is of special interest.
Where can readers find more information?
National Kidney Foundation in the USA is one potential source https://www.kidney.org/.
About Dr. Sundin
Dr Per-Ola Sundin is a physician at Örebro University Hospital in Sweden conducting his doctoral training at Örebro University. His research focus on a life course approach to understand chronic kidney disease – causes, risks and consequences.
In his clinical work he is passionate about enhancing the care of the multidiseased elderly and the training of younger physicians.