Thirawut Kongtasai and a team of other contributors from the Small Animal Department at Ghent University in Belgium published a paper in 2022 discussing the current state of biomarkers and their importance and relevance to detecting CKD in cats. Thirawut Kongtasai, DVM PhD DTBVM (Diplomate in Thai Board of Veterinary Medicine), is a veterinarian, researcher, and lecturer specializing in small animal internal medicine. Now a full-time lecturer at Mahidol University (2025).
This paper talks about how the traditional creatinine biomarker for detecting chronic kidney disease (CKD) has limitations, and that there is a new biomarker, SDMA, but there still isn’t a lot of information about how specific or reliable it is in all situations. But SDMA is promising because it appears to help catch earlier changes in glomerular problems (filtering) and tubular problems (concentration and electrolytes).
Glomerular filtration rate (GFR) is talked about as the gold standard and most sensitive test for renal function and detecting CKD. There are limitations with sampling and current techniques aren’t feasible for routine veterinary practice.
Creatinine is widely available and routinely measures. For many cases, it still gives a rough and often useful estimate of kidney filtration function. See the IRIS staging guidelines based on creatinine. BUN, or BUN + creatinine together, can provide hints of kidney disfunction. The, drawbacks I guess you could say, are that creatinine and BUN can be affected by factors not related to kidney damage, such as dehydration, high-protein diet, inflammation, or temporary stress. A more complete evaluation should be done rather than relying solely on these two numbers.
Proteinuria (protein in urine) measured by creatinine ratio (UPC) has limitations. They talk about how it can be influenced by other non-renal conditions like hyperthyroidism, infections, etc. which reduce the specificity of this marker.
Urine specific gravity (USG) helps show how well the kidneys can concentrate urine, which can be an early indicator. A persistently low or inappropriately dilute USG (common cutoff is 1.035) alongside other rising markers can help distinguish between a diagnosis and dehydration alone.
SDMA is currently promising because it appears to be more sensitive to kidney changes than the others. Cystatin C has good performance in humans and dogs, but not clinically useful in cats. FGF-23 and urinary biomarkers such as NGAL, L-FABP, KIM-1, VEGF, and HSP72 are being evaluated but concerns with overlap from non-renal conditions. The study referenced goes into much more detail on these biomarkers if you want to learn more, linked at the bottom.
The goal is to find a way to detect chronic kidney disease (CKD) earlier and start treatment earlier to improve longevity. Which is where some of these newer tests show promise, but unfortunately have not yet been validated by research.
It will be interesting to see what research comes out (or maybe is already out that I haven’t found yet) evaluating each of these.
Sources:
Renal biomarkers in cats: A review of the current status in CKD
Clinical Application of Renal Biomarkers
https://www.saspublishers.com/media/articles/SAJP-65168-170.pdf
This paper talks about how the traditional creatinine biomarker for detecting chronic kidney disease (CKD) has limitations, and that there is a new biomarker, SDMA, but there still isn’t a lot of information about how specific or reliable it is in all situations. But SDMA is promising because it appears to help catch earlier changes in glomerular problems (filtering) and tubular problems (concentration and electrolytes).
Glomerular filtration rate (GFR) is talked about as the gold standard and most sensitive test for renal function and detecting CKD. There are limitations with sampling and current techniques aren’t feasible for routine veterinary practice.
Creatinine is widely available and routinely measures. For many cases, it still gives a rough and often useful estimate of kidney filtration function. See the IRIS staging guidelines based on creatinine. BUN, or BUN + creatinine together, can provide hints of kidney disfunction. The, drawbacks I guess you could say, are that creatinine and BUN can be affected by factors not related to kidney damage, such as dehydration, high-protein diet, inflammation, or temporary stress. A more complete evaluation should be done rather than relying solely on these two numbers.
Proteinuria (protein in urine) measured by creatinine ratio (UPC) has limitations. They talk about how it can be influenced by other non-renal conditions like hyperthyroidism, infections, etc. which reduce the specificity of this marker.
Urine specific gravity (USG) helps show how well the kidneys can concentrate urine, which can be an early indicator. A persistently low or inappropriately dilute USG (common cutoff is 1.035) alongside other rising markers can help distinguish between a diagnosis and dehydration alone.
SDMA is currently promising because it appears to be more sensitive to kidney changes than the others. Cystatin C has good performance in humans and dogs, but not clinically useful in cats. FGF-23 and urinary biomarkers such as NGAL, L-FABP, KIM-1, VEGF, and HSP72 are being evaluated but concerns with overlap from non-renal conditions. The study referenced goes into much more detail on these biomarkers if you want to learn more, linked at the bottom.
The goal is to find a way to detect chronic kidney disease (CKD) earlier and start treatment earlier to improve longevity. Which is where some of these newer tests show promise, but unfortunately have not yet been validated by research.
It will be interesting to see what research comes out (or maybe is already out that I haven’t found yet) evaluating each of these.
Sources:
Renal biomarkers in cats: A review of the current status in CKD
Clinical Application of Renal Biomarkers
https://www.saspublishers.com/media/articles/SAJP-65168-170.pdf