When will my kidneys fail? Try this handy chart

My recent blood test suggests that I will develop chronic kidney disease sometime in my 90s. The standard measure of kidney function is the estimated Glomerular Filtration Rate (eGFR). Mine was calculated as 86 – which the current classification says is Stage 2 of so-called “chronic kidney disease” (CKD). Kidney Health Australia tells me that this is early stage: “You may not know you have early-stage kidney disease, as you feel completely normal. This is because there are no obvious signs. If you’re unsure, speak to your doctor. Your eGFR result will be 60-90 or more.” Hmm. Yes, I do feel completely normal.

But what will happen as I grow older? Sadly, kidney function – as with other organ functions – declines steadily with age. From the age of about 25, it drops by between 1/2% and 2% per year. If we lived long enough eventually our kidneys will ”fail“ – that is, be insufficient for normal functioning.  At that stage (stage 5 CKD) we might require regular dialysis.

When should I expect that this to happen? To help answer this, we recently developed kidney trajectory charts which plot percentiles of function with age. My current kidney function is marked (red star) on the plot below. If I stayed on the same percentile (dotted arrow), I would expect to develop stage 3a chronic kidney disease sometime in my 90s – assuming I am still alive. And I might be looking at dialysis sometime in my 130s – though I suspect I won’t need to worry about that.

Given that we are not immortal, these kidney charts are help inform an age based interpretation of function. The current definition ignores this reality, treating everyone is an immortal 25-year-old. But not  accounting for our normal age related decline can lead to overdiagnosis of much of the population.

The unfortunate reality we all face is a steady decline in our kidney, lung, heart and other bodily functions  plus parallel sensory declines in hearing and vision. Staying active and minimising other risk factors, can slow but not eliminate these declines. So we have a sort of race between our different organs for the order in which they will fail. Understanding this reality can help us prepare for and adjust to the reality of ageing. So I suppose I am lucky that I am currently looking at needing a hearing aid many decades before my dialysis.