- CDN stands for Certified Dialysis Nurse, awarded by the NNCC through C-NET-administered exams.
- The exam has 150 four-option questions (about 125 scored) in a 3-hour window at PSI testing centers.
- Chronic HD Unit (ESRD) makes up 52% of the exam - the single largest content domain.
- Eligibility requires 2,500 nephrology RN hours and 30 approved CE contact hours within 2 years.
What CDN Actually Means in Nephrology Nursing
CDN stands for Certified Dialysis Nurse, a specialty credential for registered nurses who work primarily with patients receiving hemodialysis. Unlike broader nephrology certifications that cover multiple treatment modalities, the CDN focuses squarely on the chronic in-center hemodialysis setting, along with related acute and water-treatment topics. If you're asking "what is CDN" for the first time, the short answer is: it's proof that an RN has demonstrated hands-on hemodialysis experience and passed a standardized exam validating clinical judgment in that specific practice area.
For a deeper dive into terminology and how the abbreviation is used across nursing contexts, see CDN Meaning and What Does CDN Stand For?. If you already know the basics and want the full certification overview, CDN Certification covers the credential from application to renewal.
Who Administers the CDN Exam
The CDN credential is owned by the Nephrology Nursing Certification Commission (NNCC), which works with the Center for Nursing Education and Testing (C-NET) to develop, validate, and score the exam. Testing itself is delivered through PSI, a computer-based testing vendor with test centers available year-round - meaning candidates aren't locked into a narrow annual testing window the way some other nursing certifications are.
Who Qualifies to Sit for the CDN
The CDN isn't an entry-level credential. To be eligible, a candidate must hold:
- A full, unrestricted RN license in the United States or a U.S. territory
- 2,500 hours of nephrology RN experience caring for in-center hemodialysis patients, or educating/supervising staff who do, within the prior 2 years
- 30 approved nephrology continuing-education contact hours completed in the prior 2 years
These thresholds exist because the exam assumes real bedside familiarity with dialysis access, machine troubleshooting, and complication management - not just textbook knowledge. If you're still accumulating hours or CE credits, CDN Requirements 2026: Eligibility, Prerequisites & How to Qualify breaks down how to track and document them correctly before you apply.
Exam Format, Fees, and Scoring
The CDN exam consists of 150 four-option multiple-choice questions administered over 3 hours. Not all questions count toward your final score - roughly 25 are unscored pilot items being tested for future exams, leaving about 125 scored questions. You won't know which items are pilot questions during the test, so every question should be treated as scored.
Passing requires a standard score of 95, which currently corresponds to roughly 70% correct, calculated using an Angoff-derived criterion standard rather than a simple raw percentage curve. For a full breakdown of how that scaled score is calculated and what it means for how many questions you can miss, see CDN Passing Score 2026: Exactly What You Need to Pass.
| Item | Detail |
|---|---|
| Total questions | 150 (four-option multiple choice) |
| Scored questions | ~125 (remaining ~25 are unscored pilot items) |
| Time allowed | 3 hours |
| Standard fee | $350 (includes $50 nonrefundable processing fee) |
| Partner member fee | $300 (ANNA, ASN, NKF, or NOVA members) |
| Retake fee | $200 standard / $175 for partner members |
| Passing standard | Standard score of 95 (~70% correct) |
For a line-by-line look at what that $350 (or $300) actually covers, and where the retake fee fits in if you need a second attempt, check CDN Certification Cost 2026: Complete Pricing Breakdown. And if you want to know how test-takers are actually performing under this scoring model, CDN Pass Rate 2026: What the Data Shows covers the official 2025 result of 65% across 356 administrations.
The Four CDN Exam Domains
Every CDN question falls into one of four content domains. Understanding how these are weighted is arguably the single most important piece of exam-prep information you can have, because it tells you exactly where to spend your limited study time.
Domain 1: Chronic HD Unit (ESRD) - 52%
This is, by a wide margin, the largest domain and effectively the core of the exam. It covers the day-to-day realities of caring for patients with end-stage renal disease on maintenance hemodialysis.
- Vascular access assessment, complications, and care (fistulas, grafts, catheters)
- Dialysis adequacy, prescription components, and treatment complications
- Fluid and electrolyte management specific to chronic HD patients
- Medication management, anemia management, and mineral bone disorder
Domain 2: Concepts of Kidney Disease in Adults - 32%
This domain steps back from the HD unit itself to cover the pathophysiology and broader clinical picture of kidney disease progression.
- Chronic kidney disease staging and progression
- Comorbid conditions common in the renal population (diabetes, cardiovascular disease)
- Patient and family education across the disease trajectory
- Psychosocial and quality-of-life considerations
Domain 3: Chronic HD Unit (AKI & DGF) - 8%
A smaller but distinct domain covering acute kidney injury and delayed graft function, situations that overlap with but differ meaningfully from chronic ESRD management.
- Recognizing AKI etiology and staging
- Managing dialysis for patients with delayed graft function post-transplant
- Distinguishing acute interventions from chronic maintenance protocols
Domain 4: Water for Dialysis - 8%
Often underestimated, this domain tests technical knowledge of water treatment systems that make safe dialysis possible.
- Water purification methods and system components
- Water quality standards and monitoring for dialysate
- Troubleshooting contamination and system failures
Because Domain 1 and Domain 2 together account for 84% of the exam, most candidates should structure their review time around those two areas first. For an item-by-item breakdown of subtopics within each domain, CDN Exam Domains 2026: Complete Guide to All 4 Content Areas goes deeper than the summary here.
Key Takeaway
Spend the majority of your study hours on Chronic HD Unit (ESRD) and Concepts of Kidney Disease - together they represent 84% of the exam, while Water for Dialysis and AKI/DGF combined are only 16%.
Why the CDN Credential Matters to Employers
Dialysis providers - large chains, hospital-based nephrology units, and independent clinics alike - routinely look for CDN-credentialed nurses when filling charge nurse, clinical educator, or quality-improvement roles. The certification signals that a nurse has met a documented experience threshold (2,500 hours) and passed an external, standardized clinical exam, which reduces onboarding risk for employers managing regulatory and accreditation requirements in ESRD care.
Because CDN nurses are qualified to work across in-center hemodialysis, some acute/AKI coverage, and water system oversight, the credential also opens doors beyond direct patient care, including technical and educational positions. If you're evaluating whether pursuing the credential fits your career goals, Is the CDN Certification Worth It? Complete ROI Analysis 2026 and CDN Salary Guide 2026: Complete Earnings Analysis lay out the practical tradeoffs, and CDN Jobs outlines the kinds of roles that specifically list the certification as preferred or required.
Certification Validity and Renewal
A CDN credential is valid for 3 years. When it's time to renew, nurses have two paths:
- Renewal by examination - retaking the current CDN exam under the standard eligibility and fee structure.
- Renewal by continuing education - documenting an unrestricted RN license, 1,500 nephrology RN hours during the cycle, and 45 accredited nursing CE contact hours, of which at least 15 must be nephrology-specific.
Most working dialysis nurses choose the CE renewal path since it avoids retesting, but it requires disciplined tracking of hours and CE credits across the full 3-year cycle rather than a last-minute scramble.
Building a CDN-Specific Study Plan
Generic study techniques - spaced repetition, timed practice blocks, active recall - work fine as a framework, but they only pay off when applied against the CDN's actual weighting. Given that Domain 1 (Chronic HD Unit/ESRD) is 52% of the exam, it deserves roughly half your total prep time, not an equal split across all four domains.
Chronic HD Unit (ESRD)
- Vascular access complications and troubleshooting
- Dialysis adequacy calculations and prescription adjustments
- Fluid/electrolyte and medication management scenarios
Concepts of Kidney Disease in Adults
- CKD staging and disease progression pathways
- Comorbidity management (diabetes, cardiovascular)
- Patient education and psychosocial support scenarios
AKI, DGF & Water for Dialysis
- AKI staging vs. chronic ESRD management differences
- Delayed graft function protocols
- Water treatment systems and quality monitoring
Full-Length Practice & Review
- Timed 150-question simulations under 3-hour conditions
- Review missed items by domain to rebalance final review
For a complete week-by-week study framework with more detail on pacing and review cycles, see CDN Study Guide 2026: How to Pass on Your First Attempt. If you're still gauging how challenging the exam is relative to your current experience level, How Hard Is the CDN Exam? Complete Difficulty Guide 2026 is a useful reality check before you commit to a testing date. You can also review testing windows and scheduling logistics at CDN Exam Dates 2026: Testing Windows, Deadlines & Scheduling.
Once your review is underway, running full-length timed practice sessions on our CDN practice test platform is one of the most direct ways to see how your recall holds up against 150 questions in 3 hours. Many candidates also keep a condensed reference nearby during final review - the CDN Cheat Sheet 2026: One-Page Review of Must-Know Facts is built for exactly that last-week refresher. If you want structured coursework rather than self-directed review, CDN Training covers available program options.
Frequently Asked Questions
CDN stands for Certified Dialysis Nurse, a credential from the Nephrology Nursing Certification Commission (NNCC) for RNs specializing in hemodialysis care.
The exam has 150 four-option multiple-choice questions, of which about 125 are scored and about 25 are unscored pilot items, all within a 3-hour testing window.
Chronic HD Unit (ESRD) is the largest domain, accounting for 52% of the exam content.
The standard fee is $350, or $300 for current ANNA, ASN, NKF, or NOVA members, and both amounts include a $50 nonrefundable processing fee. A one-time retake costs $200, or $175 for partner members.
Certification is valid for 3 years and can be renewed by retaking the exam or by documenting 1,500 nephrology RN hours and 45 CE contact hours, including at least 15 nephrology-specific hours.