Two related parameters
Glomerular filtration and albuminuria “are highly relevant, because screening for chronic kidney disease is based on these two parameters,” said Dr. Benedito. Glomerular filtration rate varies with age, sex, ethnicity, and body mass. It is useful for identifying the stage of the disease and for monitoring disease progression. Albuminuria, on the other hand, is an indication of the severity of the disease. It’s an early marker for kidney injury and systemic disease and is more sensitive than proteinuria. Therefore, “this factor, together with glomerular filtration rate, allows us to detect, classify, and monitor the progression of chronic kidney disease.”
On this point, Dr. Alcázar emphasized the importance of trends, since variation in glomerular filtration depends on serum creatinine, which can vary by nearly 9%. He explained that glomerular filtration rate is related to the number of nephrons remaining. A glomerular filtration rate of less than 60 mL/min implies that more than half of the nephrons in each kidney have been lost. Albuminuria informs about structural damage (that is, the condition of the remaining nephrons). It’s therefore essential to test for both parameters. “We need to be actively monitoring and then making our decisions based on trends and not on isolated results. We need to be aware of albuminuria when we make our decisions,” said Dr. Alcázar. Some studies have shown the importance of testing for albuminuria whenever creatinine level is assessed. “We need to buy into this. If we don’t do this, we’ll only ever have half the information we need.”
Reducing late diagnosis
According to the IBERICAN study, 14% of patients seen in primary care in Spain have chronic kidney disease. “This statistic should make us stop and think, own our responsibility, and ask ourselves why this screening isn’t taking place [earlier],” said Dr. Benedito. She added, “We need to head off this trend toward late diagnosis. As the disease progresses, it significantly increases cardiovascular risk and leads to higher mortality, going on dialysis, transplants, et cetera.”
Dr. Alcázar noted that 80% of nephrology cases that are referred to him come from primary care. He explained the need to understand that “these patients have a sevenfold greater risk of suffering a serious cardiovascular event within the next year than people without kidney problems.” Most of these patients will experience an event, even if they don’t undergo dialysis (stage 3 and those near stage 4).
Correct staging
Also fundamental is having a detailed understanding of how staging is performed. Dr. Benedito explained that a chart that pairs glomerular filtration rate (six categories) with the level of albuminuria (three categories) should be used during the visit. For example, a case might be classified as G3a-A2. However, the simplified form of the chart may prove more practical. It classifies chronic kidney disease as being associated with mild, moderate, and severe risk, using different colors to aid comprehension.
Dr. Alcázar noted that the latest guidelines from the European Society of Hypertension for 2023 include albuminuria as an important parameter. The guidelines indicate that for a patient with moderate or severe risk, it is not necessary to calculate their score. “It’s considered high cardiovascular risk, and steps would need to be taken for intervention.”
He then listed the tools available for reversing albuminuria. The process begins by reducing salt consumption and involves the use of medications (angiotensin-converting enzyme inhibitors/angiotensin II receptor antagonists, aldosterone receptor antagonists, glucagon-like peptide-1 analogues, and sodium-glucose cotransporter-2 inhibitors, which slow kidney damage regardless of other measures) and strict management of cardiovascular risk factors (smoking, weight management, blood glucose, hypertension, and moderate physical activity).