By David Rosenbloom
Hypertension, abnormally high blood pressure, is called the “silent killer” for good reason. And I know this from personal experience. In May 2002 at age 57 I was diagnosed with CKD5 and placed in a dialysis clinic within three weeks. Over the preceding four months, my creatinine had climbed from 1.2 to 6.0, my GFR had dropped to 10-15% and my blood pressure rose to dangerously high levels.
I had no known history of kidney or heart disease nor was I diabetic. My blood pressure was always normal when taken at my annual physical. I ate a healthy diet, exercised several times a week and was not overweight. Yet probably sometime in my early 50s, I developed hypertension that went undetected. I also had no idea that I had lived my entire life to that point on one functioning kidney, the other being vestigial. Ultrasound tests taken at the time of my diagnosis, determined that startling fact.
I, unfortunately, am not alone. According to a recent study by the John Hopkins School of Medicine:
As many as 8 million adults in the United States who have undiagnosed or early-stage hypertension may also have kidney disease, putting them at higher risk for what may be preventable kidney failure.
The study, published online in the journal Hypertension, found that 27.5% of those with diagnosed hypertension also had kidney disease, while 13.4% with normal blood pressure have kidney disease. I clearly was in this group even though I had no outward symptoms.
Of people with early-stage hypertension, 17.3% had kidney disease, while of those who had undiagnosed hypertension, 22% had kidney disease. The research team at Johns Hopkins used data collected from the National Health and Nutrition Examination Survey (1999-2006), looking at records from nearly 18,000 participants for whom information on blood pressure and kidney function was available. This is the first time any study has estimated the prevalence of kidney disease among people with varying degrees of hypertension. Kidney disease rates were based on creatinine levels in the blood and proteins in the urine, and were estimated using guidelines from the National Kidney Foundation (NFK).
Experts have estimated that nearly a third of Americans have hypertension and have no knowledge of it nor are unaware that their blood pressure is in the danger zone. Consequently, they may not seek testing and treatment for hypertension or for kidney disease. Concurrently, an estimated 26 million adults in the U.S. have CKD, and the number is growing as obesity and diabetes reaches epidemic proportions. The conclusion is unmistakable. Hypertension and kidney disease go hand in hand.
“There’s likely a very large group who have kidney disease and don’t know about it,” said Deidra C. Crews, the study’s leader and a nephrology instructor at the Johns Hopkins University School of Medicine. “For people who have pre-hypertension, an alarm should go off in their physicians that says maybe this person should be tested for kidney disease. And patients should know that having even pre-hypertension is a big risk factor for kidney disease, and they may need to make lifestyle changes.”
In the study, Crews pointed out that there is some disagreement in the medical community over what levels of kidney function and urine protein should be used to diagnose kidney disease. Her study uses current guidelines from the NKF. Some nephrologists believe those guidelines may be too loose and that stricter guidelines would paint a truer—if smaller—picture of the number of people who suffer from kidney disease. My own nephrologist at the USC Keck School of Medicine has told me that even in patients without hypertension, kidney function declines about 1% per year after age 50.
NKF and many other kidney support organizations have mounted public education campaigns to make people aware of the prevalence of hypertension, it’s link to kidney disease and the need for everyone to be tested at regular intervals. Like smoking, whose detrimental effects were first highlighted by the U.S. Surgeon General’s report over 50 years ago, the link between hypertension and CKD needs to become common knowledge. Hopefully this Johns-Hopkins study will have the same effect.