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Nephrologist’s Perspective on CKD
The Nephrologist’s Perspective on Screening and Treating CKD

Released: November 16, 2023

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Key Takeaways
  • Routine screening of CKD currently is not recommended, but the USPSTF is reevaluating this need.
  • It is critical for PCPs to accurately stage CKD; this informs the nephrologist about the severity of their patients’ condition. 
  • Other considerations (eg, measuring A1C or early identification of unexplained acute kidney injury) should be well understood when making treatment decisions.

As a practicing nephrologist, there are many considerations regarding the multidisciplinary care of patients with chronic kidney disease (CKD). According to the US Preventive Services Task Force (USPSTF) 2012 recommendation, routine screening for kidney disease is not needed for asymptomatic individuals. Rather, healthcare professionals (HCPs) have been directed to take a risk-based approach in CKD screening, such as targeting patients with obesity, diabetes, and/or hypertension at risk for CKD. Screening for these patients should begin at the recommended time based on the underlying disease. For example, HCPs should begin measuring patients’ urine albumin-to-creatinine ratio if they have had diabetes mellitus for at least 5 years. 

Of note, the USPSTF is currently reevaluating its recommendations on CKD routine screening. This is because of the evolving CKD treatment landscape. If we can screen healthy adults to detect CKD earlier, then we have a chance to use these new medications to slow disease progression. We hope that the USPSTF will release additional information soon.

Impact of Routine Screening on Asymptomatic Patients 
Screening is often done by a primary care provider (PCP) as part of patients’ routine clinical care. For example, PCPs will order a urinalysis or basic metabolic panel, which are used to screen for CKD. Sometimes PCPs also will order a test of the urine albumin-to-creatinine ratio, which is a more quantitative way of measuring how much protein (or albumin) patients are excreting. There are 3 real harms to this when screening patients who are asymptomatic. 

  • The first harm is anxiety. Labeling patients without CKD as having CKD can be anxiety provoking. The estimated glomerular filtration rate (eGFR) may be reduced simply because of the patient’s age, or a patient may be at low risk for disease progression. This may cause unnecessary worry about progression to dialysis or transplantation when, in fact, the risk is low. 
  • The second harm is false positives; a one-time test is not the best way to screen for CKD. PCPs should request 2 creatinine (eGFR) tests at least 3 months apart to confirm a CKD diagnosis. The available screening with serum creatinine may not accurately reflect the presence of this disease among those with extreme muscle mass. Herein, a cystatin C lab measurement can be used to calculate eGFR. 
  • The third harm is the cost associated with blood draws. It may seem like a small amount of blood is needed, but if you add it all together when screening everyone, it could become a large cost incrementally for the overall patient population.

Understanding Disease Staging and Its Treatment Impact
CKD is diagnosed with a decline in eGFR to <60 mL/min/1.73 m2 or the presence of blood or protein in the urine. The CKD stages are as follows: stage 3a (45-60 mL/min/1.73 m2), stage 3b (31-44 mL/min/1.73 m2), stage 4 (16-30 mL/min/1.73 m2), and stage 5 (1-15 mL/min/1.73 m2).

Patients starting in stage 3b have the potential to develop disease-related complications such as anemia, acidosis, or high phosphorus. A nephrologist should see these patients at least once per year.

Patients with stage 4 or 5 CKD absolutely must be under the care of a nephrologist and often are seen in the office more frequently. At this stage, the previously mentioned complications of CKD often worsen, and this is when the care team will start planning dialysis or transplantation as the best course of treatment.

Studies have found that later referrals to nephrologists are associated with increased morbidity and mortality. This includes patients presenting to a nephrologist with severe anemia or urgent need to start dialysis. My personal belief is that all patients with an eGFR <45 mL/min/1.73 m2 should see a nephrologist at least once. 

CKD prognosis also depends on albuminuria. The more albumin (protein) in the urine, the higher the risk for disease progression. This is staged as follows: A1 (<30 mg/g), A2 (31-300 mg/g), and A3 (>300 mg/g).

The Race-Free Equation to Measure eGFR
Race is a social construct, and HCPs need to keep this in mind, because race has no place in medicine. Furthermore, the National Kidney Foundation and American Society of Nephrology created a task force in 2020 to retool widely used eGFR equations to remove race as a determining factor. The updated equation uses many of the same variables as the original equations—such as gender, age, and serum creatinine—and has been adopted by many major laboratories. You can find this equation on the National Kidney Foundation website. 

Other Practice Considerations for CKD Management
I often tell patients that every pill, vitamin, or supplement they take is filtered by their kidneys and is potentially toxic or harmful. Therefore, it is critical that HCPs help patients minimize their medication list to keep from inducing harm. Do not have patients take pain medications unless they must, and then only for a brief period. 

In measuring hemoglobin A1C in patients with both diabetes mellitus and CKD, the test may show falsely reduced values due to anemia or acidosis, 2 complications of CKD. We recommend using continuing glucose measurements or self-monitoring of fasting or postprandial glucose. This does not mean patients cannot use their A1C measure, but it should not be the only measurement used and must not be used solely to guide decisions on treatment.

Evaluation of a Patient in the Office
What do I do when I see a patient with an increase in serum creatinine above baseline? I will look at the urine under a microscope and use an office urine dipstick to identify the presence of albuminuria, hematuria, cells, or casts. A careful history and review of lab trends may identify a condition that warrants urgent treatment, such as vasculitis. Assuming patients do not have blood or protein in their urine, I often will request repeat serum creatinine after hydrating. Many times, the first lab occurred when the patient was volume depleted (dehydrated), which results in elevated creatine (decreased eGFR). Medications such as angiotensin-converting enzyme  inhibitors, angiotensin II receptor blockers, and sodium-glucose cotransporter 2 inhibitors may result in depressed eGFR, but this is to be expected and is not indicative of worsening kidney disease.

Finally, when you notice unexplained kidney injury, I recommend referring patients for kidney biopsy. It is invasive but is the definitive test to confirm the diagnosis or severity of a particular disease. In patients with lupus, the kidney biopsy also will identify the class of lupus, and this helps nephrologists identify the optimal medication. 

Your Thoughts?
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