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Pharmacology · chapter 33 · Introduction to the Renal and Urinary Systems

Renal-Associated Fluid Volume Excess

The 14 things this section of the textbook says that you are most likely to be asked about — quoted word for word, not retold. Then 6 practice questions with the reasoning.

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Key points

  1. What fluid volume excess is

    Fluid volume excess (FVE) is identified as hypervolemia, or increased blood volume. It is related to excessive intake or inadequate output of body water.

  2. IV crystalloids can cause it

    In critically ill clients, infusion of crystalloid intravenous fluids can cause hypervolemia manifested by FVE.

  3. Other primary causes

    Additional primary causes of FVE include psychogenic water intoxication, syndrome of inappropriate antidiuretic hormone (SIADH), nephrotic syndrome, and liver cirrhosis.

  4. Three groups of kidney causes

    Altered kidney function resulting in FVE is often discussed in terms of prerenal, intrinsic renal (or intrarenal), and postrenal causes.

  5. Postrenal: urinary tract obstruction

    Obstruction of the urinary tract causes a backflow of urine into the kidneys. This increases intraluminal pressure in the tubules, causes ischemia, and decreases the GFR, resulting in FVE.

  6. Common causes of obstruction

    The common causes of obstruction include benign prostatic hypertrophy, intra-abdominal tumors, neurogenic bladder, and ureteral obstruction that is often caused by edema formation following diagnostic testing.

  7. How labs shift in FVE

    Fluid volume excess decreases sodium, hematocrit, blood urea nitrogen (BUN), and serum osmolarity values.

  8. Normal GFR

    The normal range is greater than or equal to 90 mL/minute/1.73 m 2.

  9. Low sodium from increased fluid intake

    Hyponatremia results from increased fluid intake and may be manifested by FVE, depending on the client’s kidney function.

  10. Low sodium and neurological changes

    Mildly depressed levels may cause nausea and malaise. Moderately depressed levels can cause progressive neurological alterations including headache and lethargy progressing to seizures, coma, and death.

  11. BUN falls with fluid excess

    The BUN varies inversely with the fluid volume balance; therefore, fluid volume excess will decrease the BUN.

  12. Low albumin increases edema

    Serum albumin: Decreased serum albumin levels result in the movement of fluid from the vascular space to the interstitial space, which increases edema.

  13. Normal serum osmolality

    Normal serum osmolality is 275–295 mOsm/kg H 2 O.

  14. Dilute urine in fluid excess

    The specific gravity of urine is near 1.000 in a state of fluid volume excess, which indicates dilute urine.

Terms to know

Hypervolemia
Fluid volume excess (FVE) is identified as hypervolemia, or increased blood volume.
Serum osmolarity
Serum osmolality: Serum osmolarity is determined by the concentration of all particles dissolved in a body fluid and is measured as the number of osmoles per liter.
Glomerular filtration rate
Common laboratory studies include (American Board of Internal Medicine, 2023; Padilla Abadie, 2022): Glomerular filtration rate: The GFR provides the most accurate laboratory assessment of renal function.

Practice questions

Stuck on select-all-that-apply? How to take them one option at a time.

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Every question here, with the answer

  1. A nurse is assessing a client with kidney disease for fluid volume excess. Which findings support this problem? Select all that apply.

    1. Dry, sticky mucous membranes
    2. Jugular vein distention
    3. Edema in dependent tissues
    4. Crackles in the lungs
    5. Rapid weight gain

    Answer: Jugular vein distention, Edema in dependent tissues, Crackles in the lungs, Rapid weight gain

    Common manifestations of fluid volume excess are dependent edema, ascites, adventitious breath sounds such as crackles, jugular vein distention and rapid weight gain. Dry mucous membranes are not among the listed signs of fluid excess.

  2. A client with fluid volume excess has these results. Which one is expected with hypervolemia?

    1. A decreased blood urea nitrogen (BUN)
    2. An increased serum sodium
    3. An increased hematocrit
    4. An increased serum osmolarity

    Answer: A decreased blood urea nitrogen (BUN)

    Fluid volume excess dilutes the blood and decreases sodium, hematocrit, BUN and serum osmolarity. Each of the other options describes a rise, which is the opposite of what the section describes.

  3. The urine specific gravity of a client with fluid volume excess is 1.002. How should the nurse interpret this result?

    1. The urine is concentrated because the kidneys are holding water.
    2. The result shows dehydration.
    3. The result proves a urinary tract obstruction.
    4. The urine is dilute, which fits fluid volume excess.

    Answer: The urine is dilute, which fits fluid volume excess.

    In fluid volume excess, urine specific gravity is near 1.000, which means dilute urine. Concentrated urine or dehydration would not fit, and specific gravity alone does not identify an obstruction.

  4. A client with hypervolemia has a serum sodium below the normal range. The nurse should watch most closely for which development?

    1. Muscle twitching from high sodium
    2. Increased urine concentration
    3. Increased thirst and hot, flushed skin
    4. Headache and lethargy that progress

    Answer: Headache and lethargy that progress

    Moderately low sodium can cause progressive neurological changes: headache and lethargy that can progress to seizures and coma. The other findings are not described for low sodium in this section.

  5. Which conditions can cause postrenal fluid volume excess by obstructing the urinary tract? Select all that apply.

    1. Benign prostatic hypertrophy
    2. Intra-abdominal tumors
    3. Hemorrhage
    4. Heart failure
    5. Neurogenic bladder

    Answer: Benign prostatic hypertrophy, Intra-abdominal tumors, Neurogenic bladder

    Postrenal causes are obstructions such as benign prostatic hypertrophy, intra-abdominal tumors, neurogenic bladder and ureteral obstruction. Hemorrhage and heart failure reduce renal perfusion, which makes them prerenal causes.

  6. A client's serum albumin is low and the nurse notes increasing edema. Which explanation is correct?

    1. Low albumin raises the hematocrit.
    2. Low albumin has no effect on fluid distribution.
    3. Low albumin causes the kidneys to excrete more water.
    4. Low albumin moves fluid from the vascular space into the interstitial space.

    Answer: Low albumin moves fluid from the vascular space into the interstitial space.

    Decreased serum albumin lets fluid move from the vascular space into the interstitial space, which increases edema. The other statements are not supported by the section.

Where every quote comes from

Section 33.2 Renal-Associated Fluid Volume Excess of Pharmacology for Nurses by Tina Barbour-Taylor, Leah Mueller (Sabato), Donna Paris, Dorie Weaver, OpenStax, 2024. Read the whole section free at openstax.org.

The textbook is licensed under CC BY-NC-SA 4.0. This page quotes it word for word and adds the headings, the order and the practice questions; references to the book's figures and stray spaces left by its formatting are removed. The page is shared under the same licence. Nothing here is sold.