Medical Surgical Labs BMP #1

Question

The nurse arrives for her 7a shift and receives report on a client who has had 300 mL of urine output in the last 24 hours and a BUN of 38 mg/dL and creatinine of 2 mg/dL. What do these labs indicate?

Answers

  1. Dehydration
    • Rationale:

      This answer is not correct because creatine is elevated in addition to the BUN. A creatinine over 1.3 indicates renal injury. If only the client’s BUN was elevated, then this would indicate dehydration.

  2. Kidney injury
    • Rationale:

      This answer is correct because the decreased urine output and lab results reveals acute renal injury. A normal urine output averages 30 mL/hr. Normal BUN is between 10 – 20 mg/dL. A creatinine over 1.2 mg/dL indicates kidney injury.

  3. Nephrolithiasis
    • Rationale:

      This answer is not correct because for kidney stones, calcium, uric acid levels, and a urinalysis should be tested. Creatinine may be elevated for nephrolithiasis, but in this case the labs represents kidney failure.

  4. Urinary tract infection
    • Rationale:

      This answer is not correct because to test for a urinary tract infection, labs that would be tested would be a urinalysis. The labs presented in this question indicate acute kidney failure.

Overview

BUN and creatinine measure kidney function. When BUN and creatinine are both elevated, this indicates kidney failure or injury.

Explanation

Learning Outcomes

BUN and creatinine lab studies measure kidney function. Normal BUN is between 10 -20 mg/dL. A creatinine over 1.2 mg/dL indicates kidney injury. When a client presents with an elevated BUN only, this signifies dehydration. However, if the creatinine is also elevated, over 1.3, kidney malfunction is suspected. A normal urine output averages 30 mL/hr. Serum calcium, uric acid levels, and a urinalysis would test for nephrolithiasis. A urinalysis is what is used to check for an infection in the urinary tract.

Test Taking Tip

Remember this fun phrase: “If creatinine is high, the kidneys have died.”

Video Rationale