Written by Steven Burns
From his column To Your Health
I looked at Marvin’s lab tests and sighed. Another difficult discussion. Marvin is 72 and feels fine, but he has a calculated lab value (eGFR) that shows he may have chronic kidney disease level 3. He has had high blood pressure for many years, well-controlled with medications. He’s a bit overweight, and pre-diabetic, but he exercises and takes reasonably good care of his health. So what happened to cause his kidney problem? More importantly, what can he do to prevent it from getting worse?
Chronic kidney disease affects one in seven adults in the U. S. That’s 37 million people, and many of them (40%) are not even aware they have a kidney problem.
Marvin’s abnormal eGFR is the “estimated glomerular filtration rate.” Glomeruli are the tiny clusters of blood vessels that surround a kidney tubule, and are responsible for filtering the impurities in the blood and flushing them out in urine. A “normal” eGFR value in a laboratory result is listed as greater than 60. Normal eGFR levels vary with the age of the person, ranging from 116 in the 20s, to 75 in the 70s.
The equations used for calculating the eGFR are complicated, using a person’s plasma creatinine level, blood urea nitrogen, albumin, age, height, and weight, and beyond the focus of this article.
Kidney function naturally degrades with age, so “normal” drops as we get older. If a person has conditions that cause the kidneys to worsen, their eGFR will drop, typically occurring over many years. When their eGFR reaches a certain level, they are considered to have “chronic kidney disease” (CKD).
There are five stages of CKD. Stages 1 and 2 show normal eGFR levels, so at these stages the diagnosis is usually made only when patients have an abnormal urinalysis, such as protein in the urine. Normal kidneys retain less than 1 gram of protein, so if there is more in the urine, there is a problem with the filtration system.
For most individuals, the first time they are told they have CKD is when their eGFR drops below 60, indicating level 3 (CKD 3). At this point their kidneys have lost at least 40% of their filtering function. Level 3 is divided into 3a (eGFR 45-59) and 3b (eGFR 30-44). As the eGFR drops, concern about the kidneys increases. Level 4 CKD occurs between eGFR 16-29, and level 5 indicates eGFR 15 or below. At level 5, the patient is a candidate for dialysis or transplantation.
Common causes of decreased kidney function are hypertension, diabetes, atherosclerosis (hardening of the arteries), overuse of certain medications, and genetic conditions such as polycystic kidney disease. Recurrent kidney infections can also affect function, as can obstructions such as stones or an enlarged prostate.
Marvin has an eGFR of 54, so his disease stage is 3a. He has no symptoms at all, as is the case with most patients at this stage. As kidney disease worsens he may experience fatigue, weakness, changes in urination, swelling in his feet and ankles. He may also become anemic. Later, nausea and vomiting (usually at level 4 or 5), itching, mental fogginess, shortness of breath, and muscle cramps can occur. Most people never reach CKD levels 4 or 5, so most never have any symptoms.
When Marvin comes into the office tomorrow, I will start by explaining his condition. Then, I will adjust his medications. He will need to minimize or stop the use of ibuprofen and similar medications (NSAIDs). I may need to change his blood pressure medication, as certain ones can worsen kidney function, while others help. I will recommend he lose weight and control his blood sugar levels more carefully. I’ll recommend he drink more water to make the kidneys more efficient. He will need to reduce salt in his diet, which also needs to become more balanced, with increased fruits and vegetables, and less fat and protein. We’ll work together to make his kidneys work better, and his next eGFR may be in the normal range.
If his kidney function continues to worsen, I will order an ultrasound to rule out polycystic kidney disease. If his kidney function drops below 45, into the CKD 3b range, he may need to see a kidney specialist.
Decreased kidney function is not inevitable, and you can minimize the risk of kidney disease by doing the things I’m recommending for Marvin: lose weight, avoid unnecessary medications, decrease salt intake, increase fluid intake, control blood pressure with exercise, and eat healthy.
In 1 Corinthians 6:19-20, Paul says your body is a temple, bought with a price. While he is talking about immorality here, we can extend his meaning to say that we should take care of our “temple,” by healthy living. Living well can prevent many illnesses, including chronic kidney disease. So go do that!
Dr. Steven Burns, M.D., is board-certified in family medicine and has been in practice for more than 30 years. Opinions are his own.