The Curbsiders podcast

#67: Chronic Kidney Disease Pearls with @kidney_boy, Joel Topf

November 13, 2017 | By

Take control of chronic kidney disease with tools, and tips from @kidney_boy, Joel Topf, MD Salt Whisperer and Chief of Nephrology at Kashlak Memorial Hospital. Learn which equation is best for eGFR, how to counsel patients about progression/prognosis, how to monitor patients in CKD, and who needs a referral to Nephrology. Special thanks to Annie Medina, and Justin Berk for writing/producing this show and to physician-artist, Kate Grant for her lovely and hilarious artwork (more at

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Case from Kashlak Memorial: Donald is a 56 year old African American gentleman with heart failure, hypertension, diabetes, and chronic kidney disease been seen as a new patient. He doesn’t take any medications as he just recently got his insurance back. Shoutout to Kashlak social work team! His creatinine today is 1.7, which seems to be his baseline.

Estimating GFR

Clinical Pearls:

  1. What equation should be used to estimate GFR? CKD-Epi. Based on largest population of any calculator. Best for “normal sized people.”
  2. 24 hour urine creatinine clearance equation works for all patients regardless of size e.g. bodybuilder, or amputee. Can be corrected for body surface area (click link) [Urine Cr (mg/dl) * Urine volume (ml)] / [Plasma Cr (mg/dl) * Time (min)] = CrCl
  3. How does age affect GFR? Controversial – adults are expected to lose approximately 1 ml/year of GFR past age 40.
  4. Recommended workup for new diagnosis of CKD:
    • Urinalysis: Quantify proteinuria
    • Diabetic nephropathy gradually increases proteinuria (takes years)
    • Glomerulonephritis rapidly increases proteinuria
    • Urine Albumin-to-creatinine misses multiple myeloma Bence-Jones proteins; instead use protein-to-creatinine ratio.
    • Urine dipstick only tests for albumin, not globulin fraction of protein
    • Consider biopsy if significant proteinuria and no history of diabetes
    • Ultrasound: A low yield test but may catch treatable problems e.g. athlerosclerotic disease, tumor, obstruction
  5. Staging of CKD
  6. Refer patients if:
    • You feel uncomfortable
    • Persistent hematuria
    • eGFR < 30
    • Significant proteinuria (>2gm/day)
    • Uncontrolled hypertension
  7. Monitoring of patients w/CKD:
  8. CKD 3: Twice yearly visits for urinalysis (UA), urine albumin:creatinine ratio (ACR)
  9. CKD 4:  Four times yearly visits for UA, ACR, plus annual hemoglobin, PTH
  10. Low protein diet in CKD is controversial: UpToDate suggests possible benefit, but many Nephrologists (like Dr Topf) disagree with this interpretation of the data. Read this for more insight 
  11. Most common form of anemia is iron (Fe) deficiency, not Epo deficiency elevated hepcidin → poor iron absorption, patients may need IV iron
  12. Treating secondary hyperparathyroidism lacks evidence for clinical outcomes like fracture. Consider therapy w/activated vitamin D if PTH level rising >150-200 consistently due to development of treatment resistance w/symptoms of bone pain, itching, fractures

Goal: Listeners will gain a better understanding of the diagnosis and management of chronic kidney disease and the associated complications

Learning objectives:
After listening to this episode listeners will…

  1. Diagnose and risk stratify chronic kidney disease
  2. Perform an initial workup and evaluation for new patient with CKD
  3. Identify possible interventions (pharmacological, dietary, and other) to slow CKD progression
  4. Utilize formulas to estimate GFR and Creatinine Clearance.
  5. Explain CKD to patients and counsel them on prognosis
  6. Identify the secondary complications caused by CKD and how to address them
  7. Identify patients who need a referral to nephrology
Maintenance of CKD Patients in Primary Care

Disclosures: Dr Topf lists the following disclosures on his website:

“I am on the speakers bureau for Astute Medical. I have an ownership stake in four Davita run dialysis clinics and one vascular access center. Astellas paid for my trip to Australia (Feb ’15) for me to speak at one meeting and three hospitals. Takeda Oncology made a donation to MM4MM the program that is taking me to Mount Everest in 2018.”

Time Stamps

  • 00:00 Intro
  • 03:13 Pick of the weeks
  • 08:49 Clinical Case
  • 09:36 How to explain CKD to patients
  • 12:16 Loss of GFR with age
  • 13:22 Which equation should be used to estimate GFR
  • 18:05 Creatinine clearance from 24 hour urine collection
  • 22:25 Initial workup upon diagnosis of CKD
  • 25:40 Interpreting tests for proteinuria
  • 26:52 Staging and prognosis in CKD
  • 32:00 Completing the initial workup for CKD
  • 33:52 Who needs a referral to nephrology?
  • 35:53 What labs to check in CKD and a discussion of secondary hyperparathyroidism
  • 40:32 Take home points
  • 42:30 Outro

Links from the show:

  1. Follow @kidney_boy on Twitter
  2. Check out Dr Topf’s Precious Bodily Fluids blog
  3. Mata Tea Gourd
  4. Citations Needed Podcast
  5. TED Radio Hour: Manipulation episode
  6. JAMA Article on oral semaglutide
  7. Creatinine Clearance calculator from Cornell Med
  8. Low protein diet for CKD probably ineffective

Other resources:  Check out Joel Topf’s slide deck from a recent Nephrology Update 2017 talk


  1. November 13, 2017, 4:00pm Meghan Dwyer writes:

    Hi! Tried to access Joel Topf's Nephrology Update 2017 and the link appears to be not working - wonder if his site crashed with all of us curbsider fans trying to access it?! Thanks!

  2. November 24, 2017, 6:38pm Saad writes:

    Excellent podcast. I learned many things except for the one thing I was looking for. How should a primary care provider dose medications for patients with decrease renal function and for patient’s who are going through dialysis? Please look at the drug augmentin at epocrates. Please look at the renal dosing section and have someone explain that clearly, as one would describe to a newbie. Also, what should one do in a clinical / office setting where CrCl is not able to be obtained?

  3. November 28, 2017, 6:54pm Saad writes:

    Matt, I received your response through email. Thank you for responding to me.

  4. December 7, 2017, 4:33am Julie writes:

    Hi - How the guest doctor describes how he calculates the example equation with the twenty four hour creatinine clearance and then verbally runs through an example are two different things. One one he is saying to divide by the number of minutes in the day and the other he says to multiply by the number of minutes in the day. Could you please post the correct equation? Thank you! :)

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