Diabetes Insipidus (DI): Differentials

by Carlo Raj, MD

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    00:01 Now, with these differentials, we've taken a look at these before, but the parameters here, a little bit different, but incredibly important, let me set this up.

    00:10 We have the condition and the differentials in the first column, we'll have the blood pressure when it's only relevant to your pathology, “PRA” stands for “Plasma Renin Activity,” and they have aldosterone, magnesium only when it's relevant, and urine calcium, when it's only relevant.

    00:28 That which you that you find in red, is what you're truly paying attention to, because that unique for that particular pathology, blue is going to be the consequence of, so, let's begin.

    00:38 In Bartter syndrome, where is my pathology? It is going to be in the thick ascending limb, it's a problem with the sodium potassium to chloride isn't it, so, you're going to have issues with what exactly? You're going to have issues with your concentrating ability and diluting ability, what else did we talk about with Bartter syndrome? We said that, there might be, would be, increase in prostaglandins.

    00:59 So, therefore, one of the steps of management a Bartter in fact is, indomethacin.

    01:04 In addition, Bartter syndrome has a very unique feature, in which, I want to go to the last column here, where a urine calcium is, elevated, elevated, elevated.

    01:15 On this entire table of differentials, Bartter syndrome is going to be the only one that you and I, are going to see as having hypercalciuria.

    01:26 So, therefore is it possible, just possible, that you might have secondary hypoparathyroidism? Yes or no? Good, yes, you will have secondary hyperparathyroidism.

    01:37 Now with Bartter syndrome, there would be an increase in PRA and aldosterone, keep that in mind.

    01:42 Let's move on, we have Gitelman syndrome.

    01:45 In Gitelman syndrome, where are you? My problem is in the thiazide-sensitive, do you remember that? That your sodium channel cotransporter T-gene, “T” representing the thiazide-sensitive.

    01:57 Here right off the back with Gitelman, I want you to go to urine calcium, you see the difference? Here you find your calcium to be really low, and with Gitelman, the two big things here is, an increase in PRA, plasma renin activity, and an increase in aldosterone.

    02:15 Now, in addition to your urine calcium being quite low, the serum magnesium will be low, there's enough information here with Gitelman, where once again, in terms of electrolytes and the pathophysiology, you should be able to answer any question confidently, and of the two conditions here, Gitelman and Bartter, what is more common in our society? Gitelman, Gitelman, Gitelman.

    02:41 So, you want to spend a little bit more time on Gitelman, and getting these facts down, because it's much more common than Bartter, but I can clearly say, that both are commonly asked.

    02:51 Liddle syndrome is interesting.

    02:53 With Liddle syndrome all that you want to know, is the labs here, and that'll be good enough for you to get any question right.

    02:59 I don't want you to be in a situation where, every once in a while, you're doing a question, and you might not know one condition, but to not know two or three conditions is, rather frustrating.

    03:12 Liddle syndrome, you find an increase in blood pressure, and you find a decrease in plasma renin activity and aldosterone, that is as far as you need to go now, with Liddle, know that it exists, L-i-d-d-l-e.

    03:25 Now, SIADH we talked about this earlier, we will then find an increase in, SIADH, you will not find pitting edema, you'll be euvolemic, you have a decrease in aldosterone, and a decrease in plasma renin activity.

    03:38 Once again, what did I say? “Euvolemic” why? SIADH is that really reabsorbing or secreting sodium, any of that functioning here? No.

    03:49 So, sodium is not going to be part of the equation, when you have that fluid accumulation, that's an interesting and should be known.

    03:56 And Conn syndrome, what's my problem? At the primary adrenal cortex, in which you're only producing, you see that arrow in orange, that's my primary problem, too much aldosterone, decrease in plasma renin activity, your patient has, what kind of hypertension? Secondary hypertension.

    04:15 And then we have, Reninoma.

    04:17 Reninoma, where is our problem, where do you begin? Take a look at the orange arrow, it's plasma renin activity first, and with that occurring, understand that your blood pressure here, is in fact going to be increased, this is then called secondary, once again hypertension.

    04:34 Two very important tables that give you a bunch of differentials, that are then affecting the kidney in some way, shape or form, this table might or might not be too familiar, make it familiar! All these labs will be shown, and it's important that you come up with good differentials, you'll be impressed.

    About the Lecture

    The lecture Diabetes Insipidus (DI): Differentials by Carlo Raj, MD is from the course (Nephrogenic) Diabetes Insipidus (DI).

    Included Quiz Questions

    1. Blood pressure
    2. Plasma renin activity
    3. Urine calcium
    4. Aldosterone
    5. Serum magnesium
    1. Bartter syndrome
    2. Gitelman syndrome
    3. Conn's syndrome
    4. SIADH
    5. Liddle syndrome
    1. Liddle syndrome
    2. Gitelman syndrome
    3. Bartter syndrome
    4. Reninoma
    5. Conn syndrome

    Author of lecture Diabetes Insipidus (DI): Differentials

     Carlo Raj, MD

    Carlo Raj, MD

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