I swear that attending your electrolytes course has truly opened up a new chapter for me, I mean seriously. You are an invaluable treasure to me with kindness, patience and knowledge. Thank you.
I was going to ask your thoughts on cystatin, since that is now available with iDEXX. It seems to me that it would be helpful in cases such as grape/raisin ingestion, lily, or potentially ethylene glycol or other renal toxins. Your thoughts?
Hi Nadine, this is a great question. Cystatin B is definitely an exciting and one of the first commercially available biomarkers through IDEXX. That said, its true clinical significance is still somewhat uncertain. To my knowledge, there are 3-5 manuscripts in the literature that have tested this biomarker in clinical patients with AKI or acute on chronic kidney disease: Segev et al. JVIM 2023 - showed that uCysB differentiated stable vs. progressive IRIS CKD stage 1 patients. Gordin et al. Vet Sci 2024 - showed that uCysB was higher in AKI stages 2-5 compared to healthy patients. Harjen et al. Top Comp Animal Med 2022 - showed that dogs envenomated by European Vipera species had higher uCysB than controls. There could be other papers, but many have focused on CKD patients. So, here are the facts: Healthy control patients always have uCysB levels below 50-100 ng/mL. That means if you have a patient with uCysB > 100, this is abnormal. The million-dollar question, though, is what to do with this information? How likely is it that a patient with high uCysB and normal creatinine will progress to azotemic AKI? In theory, if uCysB is high, it indicates the renal tubules have been impacted, so you want to avoid any additional renal insults (e.g., hypotension, NSAID use, etc.). However, the ultimate way to determine whether this biomarker elevation has clinical significance is through randomized studies that follow patients with high uCysB over time to see if they develop clinically significant kidney injury. These studies don’t exist in vet med yet. uCysB is not very sensitive. For example, in the Gordin et al. paper, some dogs with azotemic AKI had normal uCysB levels. Since these dogs were already azotemic, we know for sure their GFR was low, but the biomarker didn’t pick it up. If a pet is already azotemic due to AKI, don’t run uCysB, because you already know FOR SURE that AKI has developed. I think it’s reasonable to start measuring uCysB in pets exposed to toxins or experiencing shock to try to catch subclinical AKI early, but again, we don’t yet know how to act on this information. If they are eating/drinking well and well hydrated, your management likely won’t change. In other words, more studies are needed. Hope this helped a little bit!
@@vetemcrit wow, yes, thank you! You had mentioned that diuresis of AKI patients is no longer automatically recommended. Did that change or treatment of grape/raisin or lily suspected toxicities? I was thinking that early elevation in cysplatin B might be a good indication to keep them in the hospital on fluids.
@@nadinegalbraith5436 You're right-automatic diuresis for AKI patients is no longer recommended. It all depends on the patient's volume status, overall hydration, and urine output. Aggressive fluid therapy doesn’t always improve outcomes and can lead to fluid overload, which may further reduce GFR. When it comes to suspected nephrotoxin exposure like grapes/raisins or lilies, poison control services still recommend early and aggressive fluid therapy to reduce the exposure of renal tubules to the toxin. Some ECC specialists question this approach in pets that are well-hydrated and completely asymptomatic, citing the lack of evidence showing that outpatient monitoring (e.g., daily recheck of renal values and physical exam) is inferior to the conventional 48-72 hours of hospitalization with IV fluids. This debate is fascinating, and until we have prospective studies comparing these two strategies head-to-head, the jury is still out. I follow the poison control recommendations from a legal standpoint to cover my bases, but I’m not 100% convinced that putting all pets on IV fluids for 2-3 days after nephrotoxin exposure is necessarily more beneficial than a more conservative approach. I absolutely agree that, in theory, using uCysB could become a valuable diagnostic tool to help "triage" these pets and decide whether hospitalization or outpatient treatment is more appropriate. Hopefully, there will be prospective studies published on this during our lifetime. Great discussion!
This is the most valuable resource for veterinary medicine practitioners!
Thank you, Shawn!
I swear that attending your electrolytes course has truly opened up a new chapter for me, I mean seriously. You are an invaluable treasure to me with kindness, patience and knowledge. Thank you.
Thank you, my friend.
I was going to ask your thoughts on cystatin, since that is now available with iDEXX. It seems to me that it would be helpful in cases such as grape/raisin ingestion, lily, or potentially ethylene glycol or other renal toxins. Your thoughts?
Hi Nadine, this is a great question. Cystatin B is definitely an exciting and one of the first commercially available biomarkers through IDEXX. That said, its true clinical significance is still somewhat uncertain. To my knowledge, there are 3-5 manuscripts in the literature that have tested this biomarker in clinical patients with AKI or acute on chronic kidney disease:
Segev et al. JVIM 2023 - showed that uCysB differentiated stable vs. progressive IRIS CKD stage 1 patients.
Gordin et al. Vet Sci 2024 - showed that uCysB was higher in AKI stages 2-5 compared to healthy patients.
Harjen et al. Top Comp Animal Med 2022 - showed that dogs envenomated by European Vipera species had higher uCysB than controls.
There could be other papers, but many have focused on CKD patients. So, here are the facts:
Healthy control patients always have uCysB levels below 50-100 ng/mL. That means if you have a patient with uCysB > 100, this is abnormal. The million-dollar question, though, is what to do with this information? How likely is it that a patient with high uCysB and normal creatinine will progress to azotemic AKI? In theory, if uCysB is high, it indicates the renal tubules have been impacted, so you want to avoid any additional renal insults (e.g., hypotension, NSAID use, etc.). However, the ultimate way to determine whether this biomarker elevation has clinical significance is through randomized studies that follow patients with high uCysB over time to see if they develop clinically significant kidney injury. These studies don’t exist in vet med yet.
uCysB is not very sensitive. For example, in the Gordin et al. paper, some dogs with azotemic AKI had normal uCysB levels. Since these dogs were already azotemic, we know for sure their GFR was low, but the biomarker didn’t pick it up.
If a pet is already azotemic due to AKI, don’t run uCysB, because you already know FOR SURE that AKI has developed.
I think it’s reasonable to start measuring uCysB in pets exposed to toxins or experiencing shock to try to catch subclinical AKI early, but again, we don’t yet know how to act on this information. If they are eating/drinking well and well hydrated, your management likely won’t change.
In other words, more studies are needed. Hope this helped a little bit!
@@vetemcrit wow, yes, thank you! You had mentioned that diuresis of AKI patients is no longer automatically recommended. Did that change or treatment of grape/raisin or lily suspected toxicities? I was thinking that early elevation in cysplatin B might be a good indication to keep them in the hospital on fluids.
@@nadinegalbraith5436 You're right-automatic diuresis for AKI patients is no longer recommended. It all depends on the patient's volume status, overall hydration, and urine output. Aggressive fluid therapy doesn’t always improve outcomes and can lead to fluid overload, which may further reduce GFR. When it comes to suspected nephrotoxin exposure like grapes/raisins or lilies, poison control services still recommend early and aggressive fluid therapy to reduce the exposure of renal tubules to the toxin. Some ECC specialists question this approach in pets that are well-hydrated and completely asymptomatic, citing the lack of evidence showing that outpatient monitoring (e.g., daily recheck of renal values and physical exam) is inferior to the conventional 48-72 hours of hospitalization with IV fluids.
This debate is fascinating, and until we have prospective studies comparing these two strategies head-to-head, the jury is still out. I follow the poison control recommendations from a legal standpoint to cover my bases, but I’m not 100% convinced that putting all pets on IV fluids for 2-3 days after nephrotoxin exposure is necessarily more beneficial than a more conservative approach. I absolutely agree that, in theory, using uCysB could become a valuable diagnostic tool to help "triage" these pets and decide whether hospitalization or outpatient treatment is more appropriate. Hopefully, there will be prospective studies published on this during our lifetime. Great discussion!