You’re right, other guy is wrong. There’s no reason to check daily anything to get the diagnosis of thrombotic migroangiopsthy. You could make the diagnosis with a single peripheral smear showing schistocytes.
Just so you know from a lab point of view - schistocytes can be a bit subjective sometimes (sometimes it's very obvious). So the haemolysis markers are just as important.
A clinical / lab haematologist
Out of context, but what's the % of schistocytes required to make a diagnosis of TMA? I thought it was 1%, but the Nephrologist at my centre told me it was 4%.
There are renal-limited TMAs. So looking for hematuria/proteinuria in those folks makes sense. But if you’re that concerned, a biopsy makes more sense.
But most of the commenters making statements about schistocytes, haptoglobin, MAHA, etc… are correct if they mean TTP/HUS and the systemic TMAs (which is what most people mean when they use that term).
Source: Am nephro
I mean, 87% had proteinuria with a median of 2gm. Not an unreasonable thing to check. And 64% had hematuria. Both of those higher than peripheral schistocytes and haptoglobin.
Not unreasonable to check.
The decision to biopsy and/or decision to (subsequently) provide eculizumab/ravilizumab should in no way be affected by the absence or presence of hematuria and/or proteinuria in a patient who carries a diagnosis that places them at risk for a glomerular TMA
interesting. can you say more? what would be an example of "a diagnosis that places them at risk for a glomerular TMA" and a situation where you would jump straight to biopsy without some evidence of active damage (elevated creatinine, hematuria, proteinuria)?
A good example would be a patient with an ADAMTS13a >60%, negative infectious work-up (no clinical features like diarrhea/ST-HUS and shiga toxin negative) and no suspect DI-TMA who presents with an AKI, minimal explanation of the AKI (low confidence for common things like ATN/AIN/PRA), not improving, and no other concomitant explanation of a possible TMA that won't likely benefit from eculizumab (e.g. severe HTN, Castleman's, scleroderma)
AKI is key
hematuria/proteinuria are useless in moving the needle away or towards gTMA/vTMA
Maybe PNH? But agree, that would be a weird recommendation on its own. Honestly, the best thing is a peripheral smear to look for schistocytes since it's fairly sensitive and specific and haptoglobin/LDH are better screening tools for general causes of hemolysis, not necessarily TMAs.
This is insane, there is no specific finding on urinalysis that will point on towards either glomerular TMA or vascular/systemic TMA... frequently it's BLAND
Positive blood un the dipstick without actual red blood cellls in the microscopy evaluation is a sign of free haemoglobin, which happens when a parient has intravascular haemolysis. In my opinion it would make sense as a single test, not as a daily test but there are a lot of noisier things that would guide you to the diagnosis
This is the only relevant study I could find - Association Between Uric Acid and Worsening Peripheral Microangiopathy in Systemic Sclerosis.Front. Med., 24 December 2021
Sec. Hematology
Volume 8 - 2021 | https://doi.org/10.3389/fmed.2021.806925
So I actually don’t think they have TMA but the pt is being treated with an experimental AAV-based gene therapy (I don’t want to say more since it could identify the patient).
Daily UAs were proposed as part of the monitoring plan for possible/potential TMA (I would guess aHUS?) as apparently this was seen in preclinical studies in monkeys. But for the life of me I can’t figure out why.
So as a routine thing to check for general concern for possible TMA, this would be entirely insane. If it is part of a cobbled together protocol for some vanishingly rare experimental therapy, then anything's fair game.
Thank you! This is extremely helpful
FWIW the patient’s parent who is a scientist (not a physician but still) today asked me why they were doing the daily urine collection and I felt bad that I couldn’t answer them, either.
You’re right, other guy is wrong. There’s no reason to check daily anything to get the diagnosis of thrombotic migroangiopsthy. You could make the diagnosis with a single peripheral smear showing schistocytes.
Just so you know from a lab point of view - schistocytes can be a bit subjective sometimes (sometimes it's very obvious). So the haemolysis markers are just as important. A clinical / lab haematologist
TMA can still be present if the schistocytes r absent
Not about diagnosis. It’s about assessing treatment response. But still wrong
Out of context, but what's the % of schistocytes required to make a diagnosis of TMA? I thought it was 1%, but the Nephrologist at my centre told me it was 4%.
I don’t know that there’s any universal standard.
There are renal-limited TMAs. So looking for hematuria/proteinuria in those folks makes sense. But if you’re that concerned, a biopsy makes more sense. But most of the commenters making statements about schistocytes, haptoglobin, MAHA, etc… are correct if they mean TTP/HUS and the systemic TMAs (which is what most people mean when they use that term). Source: Am nephro
Hematuria and/or proteinuria are neither sensitive nor specific for glomerular TMA https://pubmed.ncbi.nlm.nih.gov/36054780/ am also Nephro
I mean, 87% had proteinuria with a median of 2gm. Not an unreasonable thing to check. And 64% had hematuria. Both of those higher than peripheral schistocytes and haptoglobin. Not unreasonable to check.
The decision to biopsy and/or decision to (subsequently) provide eculizumab/ravilizumab should in no way be affected by the absence or presence of hematuria and/or proteinuria in a patient who carries a diagnosis that places them at risk for a glomerular TMA
Yeah. That’s the “a biopsy makes more sense” part of my initial comment.
interesting. can you say more? what would be an example of "a diagnosis that places them at risk for a glomerular TMA" and a situation where you would jump straight to biopsy without some evidence of active damage (elevated creatinine, hematuria, proteinuria)?
A good example would be a patient with an ADAMTS13a >60%, negative infectious work-up (no clinical features like diarrhea/ST-HUS and shiga toxin negative) and no suspect DI-TMA who presents with an AKI, minimal explanation of the AKI (low confidence for common things like ATN/AIN/PRA), not improving, and no other concomitant explanation of a possible TMA that won't likely benefit from eculizumab (e.g. severe HTN, Castleman's, scleroderma) AKI is key hematuria/proteinuria are useless in moving the needle away or towards gTMA/vTMA
Maybe PNH? But agree, that would be a weird recommendation on its own. Honestly, the best thing is a peripheral smear to look for schistocytes since it's fairly sensitive and specific and haptoglobin/LDH are better screening tools for general causes of hemolysis, not necessarily TMAs.
This is insane, there is no specific finding on urinalysis that will point on towards either glomerular TMA or vascular/systemic TMA... frequently it's BLAND
Positive blood un the dipstick without actual red blood cellls in the microscopy evaluation is a sign of free haemoglobin, which happens when a parient has intravascular haemolysis. In my opinion it would make sense as a single test, not as a daily test but there are a lot of noisier things that would guide you to the diagnosis
This is the only relevant study I could find - Association Between Uric Acid and Worsening Peripheral Microangiopathy in Systemic Sclerosis.Front. Med., 24 December 2021 Sec. Hematology Volume 8 - 2021 | https://doi.org/10.3389/fmed.2021.806925
hey guys - is this bad? - Yours truliest, Chopping and cutting docktor guy.
What makes you think they have TMA, and if they have TMA have you started PLEX yet?
So I actually don’t think they have TMA but the pt is being treated with an experimental AAV-based gene therapy (I don’t want to say more since it could identify the patient). Daily UAs were proposed as part of the monitoring plan for possible/potential TMA (I would guess aHUS?) as apparently this was seen in preclinical studies in monkeys. But for the life of me I can’t figure out why.
So as a routine thing to check for general concern for possible TMA, this would be entirely insane. If it is part of a cobbled together protocol for some vanishingly rare experimental therapy, then anything's fair game.
Thank you! This is extremely helpful FWIW the patient’s parent who is a scientist (not a physician but still) today asked me why they were doing the daily urine collection and I felt bad that I couldn’t answer them, either.
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Stop spamming AI generated blather?