Listen to our first ever discussion with @kidney_boy, Joel Topf MD. It’s a classic diuretics episode with a fresh intro as we prepare for @NephMadness 2019 with our friends from Twitter and @AJKDonline
Dominate leg cramps, diuretic therapy, and resistant hypertension with tips from @kidney_boy, Joel Topf MD @kidney_boy, Chief of Nephrology Kashlak Memorial Hospital, co-creator @NephMadness. We start with basic renal physiology and build up to the treatment of resistant hypertension.
I enjoyed the experience immensely, but in an hour of talking off the cuff I made some embarrassing mistakes:Joel Topf MD
In describing water reabsorption I said it occured in the cortical collecting duct rather than the medullary collecting duct.
In describing my cure for cramps I tell the story of Gitelman’s and say it is like congenital loop diuretics rather than congenital thiazide diuretics
I mucked up the story about the MRFIT story and how it allowed a head to head comparison of HCTZ and chlorthalidone. I really oversold what happened.”
Written by: Matthew Watto MD
Produced by: Stuart Brigham MD and Matthew Watto MD
Cohosts: Stuart Brigham MD and Matthew Watto MD
Guest: Joel Topf MD
Glomerulus = basket filter; Proximal tubule = “big dumb reabsorption”; loop of henle = “engine of the kidney” dilutes fluid, and concentrates medullary interstitium; distal convoluted tubule = “intelligent”, finely controlled reabsorption of sodium and water; medullary collecting duct = “brains of the kidney” for fine tuning, potassium and hydrogen secreted
Diuretics get secreted into proximal tubule before acting, thus if low renal blood flow, higher doses needed to achieve effect (thus the “lasix threshold” dose) —Se Won Oh Electrolyte Blood Press 2015 PMC4520883.
Case 1: No response despite reasonable dose. Treat with higher dose or different route (e.g. IV)
Case 2: Initial diuresis, then dose wears off and 24 hour urine output inadequate. Patient is sodium avid. Treat with more frequent dosing.
Furosemide dosing: Topf dosing = Cr times 20 (alternate method: House of God dosing = age + BUN).
Bioavailability 10-100% [Brater, NEJM 1998]; Onset of action: Diuresis: Oral, SL: 30 to 60 minutes; IM: 30 minutes; IV: ~5 minutes; Duration: Oral, SL: 6 to 8 hours; IV: 2 hours; Half-life elimination: Normal renal function: 0.5 to 2 hours; End-stage renal disease: 9 hours [values from UTDOL.com]
Bioavailability 80-100% [Brater, NEJM 1998]; Onset of action: Oral, IM: 0.5 to 1 hour; IV: 2 to 3 minutes; Duration: Oral: 4 to 6 hours; IV: 2 to 3 hours; Half-life elimination: Adults: 1 to 1.5 hours [values from UTDOL.com]
Bioavailability 80-100% [Brater, NEJM 1998]; Onset of action: Diuresis: Oral: Within 1 hour; IV: 10 minutes; Onset Anti-HTN effect 4-6 weeks!; Duration: Diuresis: Oral, IV: ~6-8 hours; Half-life elimination: ~3.5 hours; Cirrhosis: 7-8 hours [values from UTDOL.com]
Kashlak Pearl: Dr Topf notes that Hyponatremia causes 1) weakness, falls 2) osteoporosis [sodium removed from bones to maintain serum sodium]
DASH diet should be used for patients with hypertension (rich in potassium).
Kashlak Pearl: Try 1 tablespoon of pickle juice as needed for nocturnal leg cramps. Make sure to SELL IT!
Resistant hypertension is diagnosed when pressure is uncontrolled despite at least 3 drugs (including a diuretic). Add spironolactone in these cases —Pathway 2 Trial, Lancet 2015.
Look for a ratio of plasma aldosterone to plasma renin activity above 20 (with older assays). Additionally, an aldosterone level above 15 suggests primary hyperaldosteronism.
Kashlak Pearl: It is OKAY to check renin and aldosterone even if your patient is on an ACEI/ARB/diuretic. But, interpretation is more challenging if on an aldosterone antagonist.
Listeners will describe the basics of renal physiology, and apply it to the use of diuretics for treating hypertension and resistant hypertension.
By the end of this podcast listeners will:
Dr. Topf reports no relevant financial disclosures. The Curbsiders report no relevant financial disclosures.
Topf, Joel. “Reboot – Diuretics, leg cramps, and resistant hypertension”. The Curbsiders Internal Medicine Podcast http://thecurbsiders.com. March 4, 2018.
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