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Renal Case: 39-year-old Woman with Type 2 DM

by Amy Sussman, MD

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    00:01 All right, let's turn to a clinical case and test our knowledge.

    00:05 So if we have a 39-year-old woman with a history of Type II diabetes mellitus, and she's admitted with a blood sugar of 700 mg/dL.

    00:14 Her exam is remarkable for a blood pressure of 115/70, pulse rate normal at 78 beats per minute, and she's breathing normally at 22 breaths per minute.

    00:23 Her jugular venous pressure is normal, and she has no peripheral edema.

    00:27 Her serum sodium is 125 mEql/L, and her serum osmolality is 315 mOsmol/kg.

    00:37 So, which statement is true regarding this patient's hyponatremia? There is inappropriate ADH release.

    00:48 There is nonosmotic stimulation of ADH due to a low effective circulating blood volume.

    00:53 This is pseudohyponatremia due to a laboratory artifact.

    00:57 or there is presence of an effective osmole in the extracellular fluid that forces water movement from the intracellular fluid compartment to the ECF.

    01:07 Now, before we actually go through those answers, let's look at our clinical case and see if there are some clues that can help us out.

    01:13 Remember what we said when we have a patient with hyponatremia.

    01:17 The first step in diagnosing anything is to determine the plasma osmolality.

    01:22 And look at this, her plasma osmolality is elevated.

    01:26 It's 315 mOsmol/kg.

    01:29 So this means she has hypertonic hyponatremia.

    01:33 Now, step two, once we have hypertonic hyponatremia we want to look for the presence of an effective osmole that's exerting a tonic effect on water.

    01:42 Here we have it.

    01:43 Look at her blood glucose 700 mg/dL.

    01:46 So let's go through our answers.

    01:48 Letter A, there's an appropriate ADH release.

    01:52 That's incorrect.

    01:53 Inappropriate ADH, or SIADH occurs in hypotonic euvolemic hyponatremia due to the presence of ADH despite normal volume status and low osmolar state.

    02:04 This patient remember is hypertonic.

    02:08 How about letter B, there's a nonosmotic stimulation of ADH due to a low effective circulating blood volume.

    02:14 Again, that's incorrect.

    02:16 The patient is euvolemic on exam.

    02:18 She has no signs of volume depletion that would invoke ADH stimulation here.

    02:24 Letter C, this is pseudohyponatremia due to a laboratory artifact.

    02:28 Also incorrect.

    02:29 This is typically going to occur remember with isotonic hyponatremia that should have a normal plasma osmolality.

    02:37 And the patient should also have a history of either hyperlipidemia or dysproteinemia.

    02:44 Now finally, letter D, there's a presence of an effective osmole in the extracellular fluid that forces water movement from the intracellular fluid compartment to the ECF.

    02:54 That is correct.

    02:55 This patient is hyperglycemic.

    02:57 She has an elevated plasma osmolality and that glucose in the ECF.

    03:01 Remember, as an effective osmole, it cannot freely move to the intracellular compartment.

    03:06 Therefore, it's exerting a tonic effect causing water movement from the ICF to that extracellular fluid volume.

    03:13 There is no primary water gain, just translocation from the ICF to the extracellular fluid compartment.

    03:20 So letter D is correct.


    About the Lecture

    The lecture Renal Case: 39-year-old Woman with Type 2 DM by Amy Sussman, MD is from the course Water Balance: Hypo- and Hypernatremia.


    Included Quiz Questions

    1. Glucose is an effective osmole that exerts a tonic effect on water.
    2. Hyperlipidemia and hyperglycemia are associated with isotonic hyponatremia.
    3. Severe hyperglycemia does not affect the fluid homeostasis of the body.
    4. The hyperglycemia will shift the water from the extracellular compartment to the intracellular compartment.
    1. Hypertonic hyponatremia
    2. Hypervolemic hypotonic hyponatremia
    3. Euvolemic hypotonic hyponatremia
    4. Isotonic hyponatremia

    Author of lecture Renal Case: 39-year-old Woman with Type 2 DM

     Amy Sussman, MD

    Amy Sussman, MD


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