Q: When (at what GFR) do you change over from hydrochlorothiazide (HCTZ) to loop diuretics? And what should be the starting dose?
The Kidney Disease Outcomes Quality Initiative (KDOQI) guidelines for hypertension and antihypertensive agents in chronic kidney disease1 (CKD) recommend replacing thiazide diuretics with loop diuretics once a patient’s glomerular filtration rate (GFR) falls below 30 mL/min/1.73 m2.
The mechanism of action for thiazide and loop diuretics differs by site of action in the kidney. Thiazide diuretics work in the distal convoluted tubules by inhibiting sodium (Na+)/chloride (Cl-) channels while the action of loop diuretics is exerted by inhibiting Na+/potassium (K+)/2Cl- channels in the thick ascending limb of the loop of Henle.2 Thiazide diuretics, with exception of metolazone, are ineffective in CKD stages 4 and 5 due to thiazide’s inability to reach the site of action.1,3
The initial furosemide dose should be 40 to 80 mg/d by mouth, preferably divided into two doses to minimize rebound sodium reabsorption.1,4 Weekly dose titrations by 25% to 50% may be made based on fluid status, blood pressure, and potassium level.1 Bumetanide and torsemide are loop diuretics that may also be used to therapeutically replace HCTZ when the GFR falls below 30 mL/min/1.73 m2. The relative potency of bumetanide: furosemide: torsemide is 1:40:20, respectively.5 The relative initiating dose equivalency of furosemide 40 mg would be bumetanide 1 mg or torsemide 20 mg.5,6
Finally, metolazone is a thiazide-related diuretic that retains its effectiveness even at GFR below 30 mL/min/1.73 m2.1,6 Metolazone can be initiated at oral doses of 2.5 to 5.0 mg/d and titrated up to 10 to 20 mg/d. Patients with residual renal function, defined as daily urine output exceeding 100 mL, may continue to use metolazone and loop diuretics even after dialysis is initated.5,7 Upon the loss of residual renal function, all diuretics should be discontinued.
Min Sik Shin
PharmD candidate, 2012, College of Pharmacy, University of Illinois at Chicago
Cheryl L. Gilmartin, PharmD
Clinical Assistant Professor, Department of Pharmacy Practice, College of Pharmacy, University of Illinois at Chicago;
Clinical Pharmacist, Ambulatory Pharmacy Services, University of Illinois Hospital and Health Sciences System, Chicago
Q: We are trying to develop renal education classes in our hospital’s general medical clinic. Participating patients (pre-renal) will be those we hope can be managed by their primary care providers in coordination with our nephrology specialists before their initial renal clinic visits. Our team of educators will include an RN, an NP, a primary care physician, and a nephrologist. Any information, models, and/or links to educational resources would be much appreciated.
Everyone loses 1% of kidney function per year after age 40. If we lived long enough, all of us would need renal education!
As you try to develop classes, one of your first concerns will be whether you want to charge for them. If they are meant to be billed for, they will take a much different form than a free kidney disease education class would. Let’s explore both.
Only Medicare pays for education classes, and patients must be at stage 4 kidney disease (ie, glomerular filtration rate [GFR], 15 to 30 mL/dL). The class can be taught in a group or an individualized format, and an RN, a dietician, or a social worker can assist—but the bulk of the class must be taught by a practitioner with a National Provider Identifier billing number (an NP, a PA, or a physician).
Medicare specifies the content of the classes and has set certain requirements regarding a class’s site and length. In addition, there must be preevaluation and postevaluation tools in place, and the number of classes over a patient’s lifetime is limited to six.
The best program available (one that contains all the needed tools, slide sets, and handouts) is Your Treatment, Your Choice8 from the National Kidney Foundation (www.kidney.org/profes sionals/KLS/YTYC.cfm). It is free, but you must be a PA, an NP, or an MD to request it.
NONPAID CLASSES AND PROGRAMS
These can be given by anybody, and the format is up to the teacher. Prevention always trumps a cure, and preventing advanced kidney disease (GFR < 60 mL/dL) fits in very well in general practice. Promoting good health habits is a common goal. To that end, instruction regarding diet, blood pressure control, blood sugar control, and smoking cessation all help slow kidney disease progression.
What’s best about offering classes like these is that you don’t have to reinvent the wheel. There are some fantastic free programs out there. Some of our favorites are available through the National Kidney Disease Education Program (NKDEP) Web site: http://nkdep.nih.gov/resources.shtml. This is a division of one of the National Institutes of Health, paid for by your tax dollars, and it offers free or very inexpensive handouts, videos, and slide sets, all written at an eighth-grade reading level.
Among the materials offered is a phenomenal tear-off sheet, “Explaining Your Kidney Test Results,” which is available in English, Spanish, Chinese, and Vietnamese (with the first five copies free, then $1 each). It illustrates the stages of kidney function using the traffic light scenario: green, yellow, or red (stage 5 CKD is the red zone) and explains what patients can do to “stay out of the red.” We consider this one of the most effective tools we can use.
NKDEP also offers free handouts listing foods high in potassium, phosphorus, protein, and sodium. Nothing is as good as a renal dietician, but these forms are an excellent alternative.
NKDEP allows you to download and reprint almost all of their information free, or you can request 50 copies of just about any item at no cost. Put your best shopper on the Web site. The amount of materials offered is truly wonderful, and you can’t beat the price.
Another program is called Kidney School (http://kidneyschool
.org), a nonprofit organization set up by the kidney community that offers all kinds of videos and slide sets at no charge.
Last, but certainly not least, is Seymour Jones and the Temple of CKD, a five-minute video put out by the Renal Support Network (RSN; www.rsnhope.org). You can request the video from RSN or find it on YouTube (www.youtube
.com/watch?v=lDJZHIVTNzo). Though hilarious, it makes excellent points about the symptoms of chronic kidney disease.
As you can see, there are many wonderful and varied (and free!) programs out there.
With the double-whammy of an aging population and increasing obesity, the number of people with kidney disease is growing exponentially; the past 20 years have seen a 67% increase in the number of patients with CKD, which now affects more than 20 million Americans. Yet in that same 20-year period, effective treatments have been developed for CKD that “can delay and, in some cases, prevent ESRD.”9 Patients with CKD need not assume there will be dialysis in their future.
Most importantly of all, we need to get out there and talk up prevention.
Kim Zuber, PA-C; Jane S. Davis, DNP, CRNP
1. K/DOQI [Kidney Disease Outcome Quality Initiative] clinical practice guidelines on hypertension and antihypertensive agents in chronic kidney disease. Am J Kidney Dis. 2004;43(5 suppl 1):S1-S290.
2. Reilly RF, Jackson EK. Ch 25. Regulation of renal function and vascular volume. In: Chabner BA, Brunton LL, Knollman BC, eds. Goodman & Gilman’s The Pharmacological Basis of Therapeutics. 12th ed. New York: McGraw-Hill Professional; 2010.
3. Sica DA, Gehr TW. Diuretic use in stage 5 chronic kidney disease and end-stage renal disease. Curr Opin Nephrol Hypertens. 2003;12(5): 483-490.
4. Cohen DL, Townsend RR. Treatment of hypertension in patients with chronic kidney disease. US Cardiology. 2009;6(2):54-58.
5. Wickersham RM, ed. Drug Facts and Comparisons. St. Louis, MO: Wolters Kluwer Health; 2009.
6. Comparison of commonly used diuretics (Detail Document). Pharmacist’s Letter/Prescriber’s Letter. February 2012.
7. DRUGDEX® System [Internet database]. Greenwood Village, Colo: Thomson Reuters (Healthcare) Inc. Updated periodically.
8. National Kidney Foundation. MIPPA Kidney Disease Education Benefit. Your Treatment, Your Choice (2010). www.kidney.org/professionals/KLS/YTYC.cfm. Accessed September 19, 2012.
9. Turner JM, Bauer C, Abramowitz MK, et al. Treatment of chronic kidney disease. Kidney Int. 2012;81(4):351-362.