Skip to content
  • About
  • Contact
  • Contribute
  • Book
  • Careers
  • Podcast
  • Recommended
  • Speaking
  • All
  • Physician
  • Practice
  • Policy
  • Finance
  • Conditions
  • .edu
  • Patient
  • Meds
  • Tech
  • Social
  • Video
    • All
    • Physician
    • Practice
    • Policy
    • Finance
    • Conditions
    • .edu
    • Patient
    • Meds
    • Tech
    • Social
    • Video
    • About
    • Contact
    • Contribute
    • Book
    • Careers
    • Podcast
    • Recommended
    • Speaking

MKSAP: 26-year-old man with back pain

mksap
Conditions
March 14, 2020
Share
Tweet
Share

Test your medicine knowledge with the MKSAP challenge, in partnership with the American College of Physicians.

A 26-year-old man is evaluated during a follow-up visit after presenting to an urgent care clinic for back pain 1 week ago. Laboratory studies at that time were significant for a serum creatinine level of 1.4 mg/dL (123.8 µmol/L); other laboratory studies, including urinalysis, were normal. A urine albumin-creatinine ratio obtained in preparation for this visit is 10 mg/g. He is a personal trainer, and his daily exercise regimen includes weightlifting. He states that his back pain has resolved. He occasionally takes ibuprofen; the last use was 1 week ago. He takes no over-the-counter supplements.

On physical examination today, vital signs are normal. BMI is 29. The patient is muscular, without signs of obesity. There is no muscle tenderness.

Which of the following is the most appropriate management?

A. Avoid all NSAID medications
B. Measure the serum creatine kinase level
C. Measure the serum cystatin C level
D. Schedule a kidney biopsy

MKSAP Answer and Critique

The correct answer is C. Measure the serum cystatin C level.

Measurement of the serum cystatin C level is appropriate for this patient. Cystatin C may be preferable to creatinine to assess kidney function in individuals with higher muscle mass. An increase in muscle mass would be expected to result in an increase in serum creatinine level in the absence of change in kidney function. This muscular man with a BMI of 29 has increase in muscle mass. Because serum creatinine is derived from the metabolism of creatinine produced by muscle, a significant increase in muscle mass would be expected to increase serum creatinine. An elevation in serum creatinine could also occur with creatine supplements, which he is not taking. This patient has a normal urinalysis and no proteinuria, all of which indicate no evidence of underlying kidney disease. Cystatin C, which is cleared by the kidney, is produced by all nucleated cells; therefore, levels are less dependent on muscle mass. Cystatin C can also be used for more accurate glomerular filtration rate estimation in these patients as a component of the Chronic Kidney Disease Epidemiology Collaboration equation.

Although NSAIDs can cause acute kidney injury, the remote and infrequent use by this patient is unlikely to have any effect on serum creatinine. The hemodynamic effects of NSAIDs will disappear within 24 hours of stopping the medication, and interstitial nephritis from NSAIDs is unlikely to present with occasional dosing and is usually associated with proteinuria. The adverse effects of renal fibrosis associated with NSAIDs are only seen with extensive and long-term use.

Creatine kinase levels can be measured to evaluate for the presence of rhabdomyolysis. Rhabdomyolysis significant enough to cause kidney injury would be expected to result in myoglobinuria reflected by heme-positive urine in the absence of red cells. No blood was seen on urinalysis.

In the absence of other changes suggesting glomerular or interstitial disease, a kidney biopsy is not necessary.

Key Point

  • Increased muscle mass can result in an increase in serum creatinine level in the absence of change in kidney function.

This content is excerpted from MKSAP 18 with permission from the American College of Physicians (ACP). Use is restricted in the same manner as that defined in the MKSAP 18 Digital license agreement. This material should never be used as a substitute for clinical judgment and does not represent an official position of ACP. All content is licensed to KevinMD.com on an “AS IS” basis without any warranty of any nature. The publisher, ACP, shall not be liable for any damage or loss of any kind arising out of or resulting from use of content, regardless of whether such liability is based in tort, contract or otherwise.

Prev

The coronavirus cost that no one can count

March 14, 2020 Kevin 0
…
Next

Will the coronavirus make primary care physicians cool again?

March 14, 2020 Kevin 0
…

Tagged as: Nephrology

Post navigation

< Previous Post
The coronavirus cost that no one can count
Next Post >
Will the coronavirus make primary care physicians cool again?

ADVERTISEMENT

ADVERTISEMENT

ADVERTISEMENT

More by mksap

  • a desk with keyboard and ipad with the kevinmd logo

    MKSAP: 36-year-old man with abdominal cramping, diarrhea, malaise, and nausea

    mksap
  • a desk with keyboard and ipad with the kevinmd logo

    MKSAP: 52-year-old woman with osteoarthritis of the right hip

    mksap
  • a desk with keyboard and ipad with the kevinmd logo

    MKSAP: 32-year-old woman with loose stools, bloating, and weight loss

    mksap

Related Posts

  • A paradigm shift in acute pain assessment and management

    Myles Gart, MD
  • Using low-dose naltrexone to treat pain

    Alex Smith
  • Why staying ahead of your pain with opioids is the wrong advice

    Myles Gart, MD
  • 5 things I wish I had known earlier about chronic pain

    Tom Bowen
  • Suboxone for pain makes sense. Why don’t more doctors prescribe it?

    Hans Duvefelt, MD
  • Blame the pain, not the opioids

    Angelika Byczkowski

More in Conditions

  • Voices from the inside: 35 years as a nurse in health care

    Virginia DeFranco, RN
  • Does silence as a faculty retention strategy in academic medicine and health sciences work?

    Sylk Sotto, EdD, MPS, MBA
  • Why personal responsibility is not enough in the fight against nicotine addiction

    Travis Douglass, MD
  • AI in mental health: a new frontier for therapy and support

    Tim Rubin, PsyD
  • What prostate cancer taught this physician about being a patient

    Francisco M. Torres, MD
  • Why ADHD in women is finally getting the attention it deserves

    Arti Lal, MD
  • Most Popular

  • Past Week

    • What’s driving medical students away from primary care?

      ​​Vineeth Amba, MPH, Archita Goyal, and Wayne Altman, MD | Education
    • How scales of justice saved a doctor-patient relationship

      Neil Baum, MD | Physician
    • The broken health care system doesn’t have to break you

      Jessie Mahoney, MD | Physician
    • How dismantling DEI endangers the future of medical care

      Shashank Madhu and Christian Tallo | Education
    • Make cognitive testing as routine as a blood pressure check

      Joshua Baker and James Jackson, PsyD | Conditions
    • The hidden cost of delaying back surgery

      Gbolahan Okubadejo, MD | Conditions
  • Past 6 Months

    • What’s driving medical students away from primary care?

      ​​Vineeth Amba, MPH, Archita Goyal, and Wayne Altman, MD | Education
    • Internal Medicine 2025: inspiration at the annual meeting

      American College of Physicians | Physician
    • What happened to real care in health care?

      Christopher H. Foster, PhD, MPA | Policy
    • Residency as rehearsal: the new pediatric hospitalist fellowship requirement scam

      Anonymous | Physician
    • Are quotas a solution to physician shortages?

      Jacob Murphy | Education
    • A faster path to becoming a doctor is possible—here’s how

      Ankit Jain | Education
  • Recent Posts

    • Voices from the inside: 35 years as a nurse in health care

      Virginia DeFranco, RN | Conditions
    • “Think twice, heal once”: Why medical decision-making needs a second opinion from your slower brain (and AI)

      Harvey Castro, MD, MBA | Tech
    • The invisible weight carried by Black female physicians

      Trisza Leann Ray, DO | Physician
    • A female doctor’s day: exhaustion, sacrifice, and a single moment of joy

      Dr. Damane Zehra | Physician
    • Addressing America’s reliance on psychotropic medication [PODCAST]

      The Podcast by KevinMD | Podcast
    • The hidden cost of malpractice: Why doctors are losing control

      Howard Smith, MD | Physician

Subscribe to KevinMD and never miss a story!

Get free updates delivered free to your inbox.


Find jobs at
Careers by KevinMD.com

Search thousands of physician, PA, NP, and CRNA jobs now.

Learn more

Leave a Comment

Founded in 2004 by Kevin Pho, MD, KevinMD.com is the web’s leading platform where physicians, advanced practitioners, nurses, medical students, and patients share their insight and tell their stories.

Social

  • Like on Facebook
  • Follow on Twitter
  • Connect on Linkedin
  • Subscribe on Youtube
  • Instagram

ADVERTISEMENT

ADVERTISEMENT

ADVERTISEMENT

ADVERTISEMENT

  • Most Popular

  • Past Week

    • What’s driving medical students away from primary care?

      ​​Vineeth Amba, MPH, Archita Goyal, and Wayne Altman, MD | Education
    • How scales of justice saved a doctor-patient relationship

      Neil Baum, MD | Physician
    • The broken health care system doesn’t have to break you

      Jessie Mahoney, MD | Physician
    • How dismantling DEI endangers the future of medical care

      Shashank Madhu and Christian Tallo | Education
    • Make cognitive testing as routine as a blood pressure check

      Joshua Baker and James Jackson, PsyD | Conditions
    • The hidden cost of delaying back surgery

      Gbolahan Okubadejo, MD | Conditions
  • Past 6 Months

    • What’s driving medical students away from primary care?

      ​​Vineeth Amba, MPH, Archita Goyal, and Wayne Altman, MD | Education
    • Internal Medicine 2025: inspiration at the annual meeting

      American College of Physicians | Physician
    • What happened to real care in health care?

      Christopher H. Foster, PhD, MPA | Policy
    • Residency as rehearsal: the new pediatric hospitalist fellowship requirement scam

      Anonymous | Physician
    • Are quotas a solution to physician shortages?

      Jacob Murphy | Education
    • A faster path to becoming a doctor is possible—here’s how

      Ankit Jain | Education
  • Recent Posts

    • Voices from the inside: 35 years as a nurse in health care

      Virginia DeFranco, RN | Conditions
    • “Think twice, heal once”: Why medical decision-making needs a second opinion from your slower brain (and AI)

      Harvey Castro, MD, MBA | Tech
    • The invisible weight carried by Black female physicians

      Trisza Leann Ray, DO | Physician
    • A female doctor’s day: exhaustion, sacrifice, and a single moment of joy

      Dr. Damane Zehra | Physician
    • Addressing America’s reliance on psychotropic medication [PODCAST]

      The Podcast by KevinMD | Podcast
    • The hidden cost of malpractice: Why doctors are losing control

      Howard Smith, MD | Physician

MedPage Today Professional

An Everyday Health Property Medpage Today
  • Terms of Use | Disclaimer
  • Privacy Policy
  • DMCA Policy
All Content © KevinMD, LLC
Site by Outthink Group

Leave a Comment

Comments are moderated before they are published. Please read the comment policy.

Loading Comments...