Which statement describes the usefulness of SDMA as a biomarker and when it becomes abnormal?

• A. It is a hepatic biomarker
• B. It increases with kidney disease earlier than creatinine; abnormal when above reference interval
• C. It indicates dehydration
• D. It decreases with CKD

Answer: (B)

SDMA is a kidney function biomarker that rises as GFR declines, often increasing earlier than creatinine. It is produced and cleared by the kidneys, so when filtration drops, SDMA accumulates in the blood. This makes it useful for detecting CKD earlier, and it tends to be less influenced by muscle mass than creatinine, which can help avoid false negatives in dogs or cats with low muscle mass. Abnormal SDMA means it is above the reference interval, signaling reduced renal function. This is not a hepatic marker, does not specifically indicate dehydration, and it does not decrease with CKD; in fact, it increases as kidney function worsens. Clinically, SDMA is often used alongside creatinine to assess kidney function and catch early CKD.