Casts in Urine Sediment

by Carlo Raj, MD

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    00:00 Cast What's the difference? Cells individually, they're not aggregated.

    00:07 But if you have a bunch of cells that aggregate Well clinically, you no longer call them cells, you call them cast Are we clear? Now there are different types of cast Now before I begin once more Cast, you clinically mean damage damage damage to the kidney Clear? I'm sorry damage where? to the kidney.

    00:27 Cast. The cells? not so specific.

    00:30 Prime example, I gave you something like neutrophils.

    00:34 Neutrophils could be found with urethritis, cystitis, pyelonephritis, right? But if you find WBC cast, then that will be for, which diagnosis? Good. Pyelonephritis.

    00:48 So casts are formed in tubular, what tubular? the urine, the nephron.

    00:53 lumens in the kidney, has to be the kidney They're composed of protein matrix, Now you've heard of Tamm-Horsfall proteins These are normal components, okay.

    01:04 They're normal components of urine findings.

    01:07 However, there are times when you would find this in settings of excess, excess lights chains-Bence Jones.

    01:14 Maybe something like your multiple myeloma Now within the Tamm-horsfall protein, within which are entrapped cells, debris of protein leaking through the glomeruli So whatever it is that is accumulating within the urine It then combines with your uromodulin or Tamm-horsfall and all of this is then going to form a cast, an aggregate What kind of aggregates do you want to know, and I'll show you pictures as well Hyaline cast. Now this could be part of normal.

    01:44 And then in medicine, in pathology, what we do as well is the fact that you then take these casts that either are cellular or acellular And as we go through the various cast, we well then take a look at cellular, acellular type of cast Now hyaline is a aggregation of protein, and it's ghost like.

    02:05 which means that when we take a look at this cast, of hyaline which I'll show you it is very, very translucent. Very transparent.

    02:13 Like this invisible little alien in your urine, it's amazing.

    02:17 But it is a cast though, it's aggregation.

    02:20 Now, no significance truly in absence of proteinuria.

    02:24 So you could find this in a patient who's an athlete, who just went for a crazy workout.

    02:29 And you might find hyaline cast because it's just normal damage that might be taking place in which a protein are now aggregating.

    02:36 What is my topic? Cast.

    02:38 Where am I? kidney specifically.

    02:40 Now RBC cast. Not RBC as cells.

    02:44 RBC cast, so you're reading a journal, you're reading a clinical vignette Whatever it may be, you know you're tired, make sure that you're paying attention Does that have a cast associated with it, or not? If it has a cast associated with it, no doubt- kidney damage What kind of glomerulonephritis is more having or leans towards having this cast? Nephritic, nephritic, nephritic..

    03:10 I told you nephritic now this is the third to fourth time that I've told you to focus on H - hematuria, hypertension And with that hematuria, you're going to find RBC cast Example of nephritic? The most common is IgA.

    03:25 Call it Berger but I would know this as being IgA nephropathy.

    03:29 Another very important one, with nephritic would be Post-streptococcal glomerulonephritis WBC cast. now you'd want to be careful here.

    03:37 I'm gonna give you two differentials.

    03:39 What does WBC mean to you, well we all know what it is.

    03:42 But there are two major types of WBCs that are involved in kidney disease.

    03:47 One would be neutrophils, the other one would be eosinophils.

    03:51 Interesting.

    03:52 So just because you'd find a WBC cast, the next question you ask yourself What are these cast made up of? If they're neutrophils, take a look at the differential We have pyelonephritis.

    04:04 Flank pain, urinary tract infection? Maybe.

    04:06 Either hematogenous spread or ascending spread, discussed in Micro.

    04:12 If the WBC cast is made up of eosinophils, then this is "an allergic reaction" Maybe your patient is allergic to penicillin And has what's known as, well these allergies in which the eosinophils causes damage and this is called Tubal Interstitial Nephritis or Acute Interstitial Nephritis What kind of cast are these? They're WBC made up of eosinophils.

    04:40 The other big one too, clinically is called atheroemboli with the eosinophils as well.

    04:46 Cast.

    04:47 Now we take a look at Renal Tubular Cast.

    04:50 What's this mean to you? Now, here be careful. Look at the differential.

    04:56 This is Acute Tubular Necrosis.

    04:59 In a previous discussion, what did we see? Acute Interstitial Nephritis or Acute Interstitial Necrosis What's the difference? In Acute Interstitial Nephritis or Necrosis, the problem is the fact that the patient was maybe allergic to something, a drug perhaps such as a penicillin or sulfonamide.

    05:20 Once the offending agent has been removed, guess what, you take care of the pathology Completely different here.

    05:26 With ATN, acute tubular necrosis, who is dying.

    05:30 The tubular epithelial cells are dying.

    05:33 What's a definition of a cast? aggregates of your cells.

    05:38 So the tubular epithelial cells are then dying because they're undergoing well what kind of predisposing factor or condition result in acute tubular necrosis? ischemia being the most common.

    05:49 So say that your renal artery is undergoing ischemia due to atherosclerosis.

    05:54 At some point in time with the ischemia taking place, Then you're going to cause necrosis to whom? The tubular epithelial cells.

    06:03 What are these tubular epithelial cells going to do? They're gonna fall into the urine. They're dying, they're crumbling.

    06:09 And as they crumble, the walls do, they're gonna form these renal tubular cell cast.

    06:16 Are these acellular, cellular? Well these are once again dead cells, they're necrotic.

    06:22 The walls of the nephron are dying.

    06:24 Let's continue.

    06:25 Fatty cast. It contains lipids, cholesterol.

    06:27 You're thinking about once again, the concept that I gave you was that when there's decreased protein in your patient, maybe due to nephrotic syndrome, maybe due to cirrhosis fatty cast, oval fat bodies- found with nephrotic.

    06:42 Example, something like lipoid nephrosis.

    06:45 What's the most common cause of nephrotic syndrome in a child? Minimal change disease.

    06:52 Now we'll come to a type of acellular cast.

    06:56 And it's known as waxy, broad cast.

    06:59 What's this mean? It means that here the aggregates that you're seeing, What your accelular are large and they're waxy like.

    07:07 They're not hyaline.

    07:09 Hyaline was acellular too, wasn't it? And that was an aggregate of proteins.

    07:14 But that would be insignificant in terms of its clinical relevance.

    07:18 Here however with waxy, broad cast, completely different.

    07:22 Take a look at your diagnosis , Maybe the sign of chronic renal failure, refractory.

    07:29 Okay these are acellular, waxy broad cast. Put those together.

    About the Lecture

    The lecture Casts in Urine Sediment by Carlo Raj, MD is from the course Urinalysis.

    Included Quiz Questions

    1. Indicates damage to the kidney.
    2. Indicates damage to the lungs.
    3. Indicates damage to the liver.
    4. Indicates damage to the aorta.
    5. Indicates damage to the pituitary gland.
    1. WBC casts
    2. Renal tubular casts
    3. Muddy brown casts
    4. Hyaline casts
    5. RBC casts
    1. Significant damage in the absence of proteinuria.
    2. No significant damage in the absence of proteinuria.
    3. Acellular casts
    4. Ghost-like appearance
    5. Formed in the tubular lumen in the kidney.
    1. Waxy casts
    2. Fatty casts
    3. RBC casts
    4. Hyaline casts
    5. Muddy brown casts

    Author of lecture Casts in Urine Sediment

     Carlo Raj, MD

    Carlo Raj, MD

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