The CDN (Certified Dialysis Nurse) is a nursing certification awarded by NNCC.
NNCC publishes the official exam outline, eligibility rules and fees — see NNCC's official page before you book.
Twenty CDN (Certified Dialysis Nurse) questions, with the answers hidden until you want them — covering Management, Pathology, Procedures, Pharmacology and more. They are real cards from our 1050-card deck, not the 30 on the free preview page, so you can use both. Work through them cold, then use your score below to decide what to study next. NNCC publishes the official exam outline — check it for the real blueprint.
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A dialysis patient's K+ is 6.8 mEq/L. What is the earliest ECG change expected, and what progression should the nurse monitor for if levels continue to rise?
Show answer →Earliest change: Tall, peaked T waves. Progression: PR interval prolongation, loss of P wave, QRS widening, and finally the sine wave pattern leading to V-fib/asystole. Exam Tip: NNCC often tests the sequence of ECG changes. Peaked T waves are the classic first sign, but QRS widening indicates imminent cardiac arrest risk. Distinguish between peaked T waves and the hyperacute T waves seen in early MI.
A patient with K+ 7.5 mEq/L shows QRS widening. The MD orders Calcium Gluconate 1g IV. What is the primary purpose of this medication, and how long does its effect last?
Show answer →Purpose: Membrane stabilization. It antagonizes the cardiotoxic effects of K+ by increasing the threshold potential, but it DOES NOT lower serum K+. Duration: Short-lived (30-60 mins). Exam Tip: If ECG changes persist, the dose can be repeated in 5-10 mins. Distinguish between stabilizing the heart (Calcium) and shifting K+ (Insulin/Albuterol). Calcium Chloride provides more elemental calcium but is more caustic to veins than Gluconate.
When administering 10 units of IV Regular Insulin for hyperkalemia, why is 50mL of Dextrose 50% (D50) typically given simultaneously, and what is the mechanism of action?
Show answer →Mechanism: Insulin stimulates the Na-K-ATPase pump, shifting K+ into cells. D50 is given to prevent hypoglycemia. Rationale: In dialysis patients, the glucose peak usually occurs earlier than the insulin peak, so monitor BG for up to 6 hours. Exam Tip: NNCC emphasizes monitoring for delayed hypoglycemia, especially in patients with ESRD who have reduced insulin clearance. If pre-treatment BG is >250 mg/dL, D50 may be held.
A patient is scheduled for emergency dialysis for K+ 7.2. Which dialysis prescription factors maximize the potassium removal rate during the first hour?
Show answer →1. High Blood Flow Rate (Qb). 2. High Dialysate Flow Rate (Qd). 3. Large surface area dialyzer (High flux). 4. Low Potassium Dialysate (0K or 1K). Exam Tip: Be cautious with 0K baths in patients on Digoxin due to the risk of arrhythmias from rapid K+ shifts. The gradient between blood and dialysate determines the rate of removal. Most K+ removal occurs in the first 2 hours of treatment.
A patient's lab result shows a K+ of 6.5 mEq/L, but the patient is asymptomatic with a normal ECG. What pre-analytical errors in a dialysis unit could cause pseudohyperkalemia?
Show answer →Causes: 1. Hemolysis (vigorous shaking of tubes). 2. Drawing labs from a line with heparin/potassium dwell. 3. Fistula/Graft milking or fist clenching during draw. 4. Prolonged tourniquet time. 5. Delayed processing (K+ leaks from WBCs/Platelets). Exam Tip: If K+ is high but ECG is normal, always verify the sample integrity and re-draw before aggressive treatment, unless the patient is symptomatic or has missed multiple treatments.
How does nebulized Albuterol assist in treating hyperkalemia, and what is a common contraindication in the dialysis population?
Show answer →Mechanism: Beta-2 agonists stimulate the Na-K-ATPase pump to shift K+ intracellularly. Dose: Usually 10-20mg (much higher than asthma doses). Contraindication: Tachyarrhythmias or severe CAD. Exam Tip: Albuterol is an adjunct and should not be used as monotherapy. It can lower K+ by 0.5-1.5 mEq/L. NNCC may test the synergistic effect when used with insulin—they work better together than either alone.
A patient with Acute Tubular Necrosis (ATN) enters the Diuretic Phase, with urine output increasing to 4L/day. What is the priority nursing assessment during this phase?
Show answer →The priority is monitoring for fluid volume deficit and electrolyte imbalances, specifically hypokalemia and hyponatremia. In the diuretic phase, the kidneys can excrete volume but cannot yet concentrate urine or efficiently reabsorb electrolytes. Clinical Pearl: The diuretic phase indicates that glomerular filtration is recovering, but tubular function remains impaired. Patients are at high risk for dehydration and cardiac arrhythmias due to rapid potassium loss. NNCC exams often test the transition from the oliguric phase to the diuretic phase regarding electrolyte shifts.
Which phase of Acute Kidney Injury is characterized by a significant decrease in GFR, metabolic acidosis, and the highest risk for life-threatening hyperkalemia?
Show answer →The Maintenance (Oliguric) Phase. During this phase, which can last 1–3 weeks, the GFR is at its lowest. The damaged tubules cannot excrete potassium, hydrogen ions (leading to metabolic acidosis), or nitrogenous wastes (leading to uremia). Clinical Reasoning: Nurses must monitor for AEIOU indications for dialysis: Acidosis, Electrolyte imbalance (K+), Ingestion (toxins), Overload (fluid), and Uremia. Distinguish this from the Initiation phase (the period of insult) where damage is potentially reversible if the cause is corrected immediately.
A 72-year-old male with BPH presents with sudden onset anuria and suprapubic pain. SCr is 3.5 mg/dL. What classification of AKI is most likely, and what is the definitive diagnostic step?
Show answer →This is Postrenal AKI (obstructive). Sudden, complete anuria is a hallmark sign of obstruction, whereas prerenal or intrinsic AKI usually presents as oliguria. The definitive diagnostic step is a renal ultrasound to visualize hydronephrosis or bladder scan/catheterization to check for post-void residual. NNCC Tip: Postrenal AKI is often reversible if the obstruction is relieved quickly. Common causes tested include BPH, kidney stones, and pelvic tumors.
A patient's eGFR was 55 last year and is 48 this year. Does this meet the KDIGO definition for rapid progression of CKD? What is the threshold?
Show answer →Yes. Rapid progression is defined as a sustained decline in eGFR of >5 mL/min/1.73m² per year. A decline of 7 mL/min in one year (55 to 48) meets the threshold. Clinicians also monitor for a certain drop in GFR category (e.g., G3a to G3b). Exam Tip: Be prepared to calculate the rate of decline over a multi-year scenario to identify high-risk patients.
At what specific KDIGO GFR stage is it mandatory to begin formal education on Kidney Replacement Therapy (KRT) modalities, including transplant and home dialysis?
Show answer →Formal KRT education and referral for vascular access or transplant evaluation should begin in Stage G4 (GFR 15-29 mL/min/1.73m²). Specifically, KDIGO recommends referral to a multi-disciplinary team when GFR <30 to allow adequate time for vein mapping, fistula maturation, or pre-emptive transplant listing. NNCC focus: Timely referral and education are key quality indicators for dialysis nurses.
Why is the rope ladder technique preferred over area cannulation for a maturing arteriovenous fistula (AVF)?
Show answer →Rope ladder involves rotating cannulation sites along the entire length of the vessel. This prevents localized weakening of the vessel wall, reducing the risk of pseudoaneurysms and stenosis. Area cannulation (repeatedly hitting the same small area) leads to "one-site-itis," thinning the wall and increasing rupture risk. Exam Tip: NNCC emphasizes site rotation to extend the lifespan of the access and maintain vessel integrity over years of treatment.
A patient's AVF shows localized bulging and skin thinning at a frequent cannulation site. The nurse identifies this as a pseudoaneurysm. What is the most appropriate action regarding site selection for the next treatment?
Show answer →The nurse must avoid the pseudoaneurysm and use the rope ladder technique to find healthy segments of the vessel above or below the affected area. Cannulating a pseudoaneurysm increases the risk of life-threatening hemorrhage and spontaneous rupture. Exam Strategy: NNCC often tests the "Look, Listen, Feel" assessment; skin thinning or shiny skin over a bulge is a red flag requiring immediate referral to a vascular surgeon and strict avoidance of that site.
For a standard AVF using the rope ladder technique, what is the recommended angle of needle insertion, and how does the depth of the vessel influence this?
Show answer →The standard angle is 25 to 35 degrees. However, the angle must be adjusted based on the depth of the fistula: shallower for superficial vessels and steeper for deeper vessels. Once the "flashback" is seen, the angle is lowered to parallel with the skin to advance the needle. Exam Tip: Steeper angles (>45 degrees) increase the risk of posterior wall infiltration, while too shallow an angle may cause the needle to scrape the intima.
How does a high Volume of Distribution (Vd >2 L/kg) affect the dialyzability of a drug, and what is the clinical implication for a nurse managing an overdose in a dialysis patient?
Show answer →Drugs with a high Vd (e.g., Digoxin, Tricyclic Antidepressants) are distributed extensively into peripheral tissues and fat, leaving very little drug in the plasma available for removal by the dialyzer. Even if the drug is small and water-soluble, hemodialysis is ineffective for rapid removal because the plasma is cleared quickly while the tissue stores remain high. Clinical Pearl: This often leads to a rebound effect, where plasma levels rise again hours after dialysis as the drug redistributes from tissues back into the blood. NNCC focuses on identifying that dialysis is NOT the primary treatment for high-Vd drug toxicities.
Which characteristic of a drug's molecular weight (MW) is the primary cutoff for removal by a standard low-flux versus a high-flux dialyzer membrane?
Show answer →Low-flux membranes are generally limited to clearing small molecules (MW <500 Da) like urea and creatinine. High-flux membranes, used in most modern 2026 clinics, can clear middle molecules with MW up to 15,000-20,000 Da (e.g., Beta-2 Microglobulin). Exam Tip: If a question asks about a drug like Heparin (MW 3,000-30,000 Da), remember it is generally NOT cleared by dialysis due to its size and high protein binding, regardless of flux. However, many antibiotics fall into the 500-1500 Da range and are cleared significantly ONLY by high-flux membranes.
Before performing cannulation on a patient's arteriovenous fistula, the nurse realizes they just touched the patient's chart at the nursing station. According to CDC guidelines, what is the required hand hygiene sequence before proceeding?
Show answer →The nurse must perform hand hygiene (alcohol-based hand rub or soap and water) immediately before touching the patient and again specifically before performing the aseptic task (cannulation). **Rationale:** CDC Five Moments for Hand Hygiene specifies that hand hygiene must occur: 1) Before touching a patient, 2) Before clean/aseptic procedures, 3) After body fluid exposure, 4) After touching a patient, and 5) After touching patient surroundings. **Exam Tip:** The NNCC emphasizes that clean tasks (like charting) and dirty tasks (like touching the environment) must be separated from aseptic tasks (cannulation/access) by hand hygiene. Distractors often suggest that wearing gloves replaces the need for hand hygiene; it does not.
During a busy shift, a nurse notes their hands are not visibly soiled but they have just completed a dressing change on a central venous catheter. Is an alcohol-based hand rub (ABHR) or soap and water the preferred method for hand hygiene?
Show answer →Alcohol-based hand rub (ABHR) is the preferred method for hand hygiene in dialysis settings when hands are not visibly soiled. **Rationale:** ABHR is more effective at reducing bacterial counts on hands, is faster, and is less irritating to skin than repeated soap and water washing. **Exceptions (Must Know):** Soap and water MUST be used if: 1) Hands are visibly soiled with blood or body fluids, 2) After using the restroom, or 3) When caring for a patient with suspected or confirmed Clostridioides difficile (C. diff) or Norovirus during an outbreak. **Exam Strategy:** Watch for distractors mentioning routine use of soap and water. CDC and NNCC prioritize ABHR for routine clinical contact to increase compliance.
How does Antidiuretic Hormone (ADH) specifically increase water reabsorption in the medullary collecting duct, and what is the primary stimulus for its release in a dialysis patient?
Show answer →ADH (Vasopressin) binds to V2 receptors, triggering the insertion of Aquaporin-2 channels into the apical membrane of collecting duct cells. The primary stimulus is increased plasma osmolality (detected by hypothalamic osmoreceptors) or significant volume depletion (baroreceptors). **Clinical Pearl:** Dialysis patients with high interdialytic weight gains (IDWG) often have suppressed ADH if they are fluid overloaded, but may have high ADH if they consume high-sodium diets, triggering thirst.
A dialysis patient's labs show: HBsAg negative, Anti-HBc negative, and Anti-HBs 15 mIU/mL. How should the nurse interpret these results and what is the required screening frequency?
Show answer →Interpretation: Immune due to vaccination. Rationale: The presence of Anti-HBs (Surface Antibody) ≥10 mIU/mL without Anti-HBc (Core Antibody) indicates successful immunization. Dialysis-specific protocol: These patients do not require monthly HBsAg screening. Per CDC and NNCC guidelines, Anti-HBs levels should be retested annually. If the titer falls below 10 mIU/mL, a booster dose is required. Exam Tip: Only HBsAg-positive patients require physical isolation; immune patients can be treated in the general population.
17–20 correct
Strong. Move to the hardest material and timed drilling rather than re-reading topics you already know.
12–16 correct
A normal mid-prep score. Work the topics you missed one at a time — the topic pages below are built for exactly that.
Under 12 correct
Early days. Go topic by topic instead of taking more mixed tests: pick your weakest area below and drill it until the questions feel routine.
Management questions
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Pathology questions
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Procedures questions
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Pharmacology questions
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Basics questions
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Physiology questions
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Diagnostics questions
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Try 30 free CDN cards firstIt is 20 real question-and-answer cards from our 1050-card CDN deck, mixed across topics so it feels like the breadth of the exam. It is not the official NNCC exam and is not endorsed by NNCC — for the official outline and any official practice material, go to NNCC directly.
Use the bands on this page as study guidance, not as a pass mark: we do not publish a passing score for the CDN because NNCC sets it, and it can change. Confirm the current standard in the official handbook.
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