The RDN (Registered Dietitian Nutritionist) is an allied-health certification awarded by CDR.
CDR publishes the official exam outline, eligibility rules and fees — see CDR's official page before you book.
Twenty RDN (Registered Dietitian Nutritionist) questions, with the answers hidden until you want them — covering Management, Pathology, Physiology, Procedures and more. They are real cards from our 1070-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. CDR publishes the official exam outline — check it for the real blueprint.
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Answer each one before opening it. Keep score as you go.
A client with Type 2 Diabetes tells the RDN, I know my blood sugar is high and I should probably cut back on soda, but I just don't have the time to deal with it right now. According to the Transtheoretical Model, what stage of change is this client in?
Show answer →The client is in the **Contemplation** stage. **Rationale:** The client acknowledges the problem (I know... I should) but is ambivalent and not yet ready to commit to action within the next 30 days. **Exam Strategy:** Distinguish from Precontemplation (denial or no intention to change) and Preparation (intent to act in the immediate future, usually 30 days). CDR often uses ambivalence or pros vs. cons weighing as a hallmark of Contemplation.
During a nutrition assessment, a client states, I bought a new heart-healthy cookbook and plan to start a low-sodium diet next Monday. Which stage of change does this represent, and what is the RDN's primary goal for this stage?
Show answer →**Stage:** Preparation. **Goal:** Assist the client in developing a concrete action plan and setting SMART goals. **Rationale:** Preparation involves the intention to change within the next 30 days and small behavioral steps (e.g., buying a cookbook). **Clinical Pearl:** The RDN should help the client identify potential barriers and social support before the Action phase begins. If the client has not set a specific date or taken a small step, they are likely still in Contemplation.
In the Transtheoretical Model, the Decisional Balance shift where the Pros of changing health behaviors begin to outweigh the Cons typically occurs during the transition between which two stages?
Show answer →Transition from **Contemplation to Preparation**. **Rationale:** In Precontemplation, Cons > Pros. In Contemplation, Pros = Cons (creating ambivalence). In Preparation, the Pros finally outweigh the Cons, leading to the decision to act. **Exam Tip:** CDR focuses on this crossover point. If a patient is still listing more reasons NOT to change than reasons TO change, they have not yet reached the Preparation stage. Management of the patient requires shifting this balance via consciousness raising and self-reevaluation.
A client has successfully followed a Mediterranean diet for 8 months. They report feeling more energetic but worry about upcoming holiday parties. What stage of change are they in, and what intervention is most appropriate?
Show answer →**Stage:** Maintenance. **Intervention:** Relapse prevention, problem-solving, and social support. **Rationale:** Maintenance is defined as sustaining the behavior change for 6 months or longer. **Exam Tip:** For clients in Maintenance, the RDN should focus on identifying high-risk situations (like holidays or stress) and developing coping strategies to prevent regression to earlier stages. If the behavior change was less than 6 months, it would be the Action stage.
Which Process of Change involves a client cognitively and affectively reassessing their self-image with and without a specific unhealthy habit, and in which TTM stage is this process most effectively utilized?
Show answer →**Process:** Self-Reevaluation. **Stage:** Contemplation (moving toward Preparation). **Rationale:** Self-reevaluation helps clients realize that the healthy behavior is an important part of who they want to be (identity). **Clinical Pearl:** Contrast this with Environmental Reevaluation, which looks at how the habit affects others (e.g., How does my smoking affect my kids?). Both are experiential processes used in early stages to build motivation.
An RDN is hired to manage a corporate wellness program. A needs assessment shows most employees are in the Precontemplation stage regarding physical activity. What is the most effective management strategy to move these employees forward?
Show answer →**Consciousness Raising (Increasing Awareness).** **Rationale:** For Precontemplators, providing information, education, and personalized feedback about the risks of inactivity is the priority. **Common Distractor:** Setting SMART goals or providing gym memberships. These are Action or Preparation oriented interventions. In Precontemplation, the individual does not believe a problem exists; therefore, doing interventions will be ignored or met with resistance.
What is the primary hormonal driver of the intracellular electrolyte shift observed in Refeeding Syndrome?
Show answer →Insulin is the primary driver. During starvation, the body is in a catabolic state (low insulin, high glucagon). Reintroduction of carbohydrates triggers insulin secretion, which stimulates the Na+/K+ ATPase pump and glucose uptake. This causes an abrupt shift of potassium, magnesium, and phosphate from the extracellular space into the cells. Resulting serum hypophosphatemia is the hallmark sign. Exam Tip: CDR often tests the shift from fat metabolism (ketones) back to carbohydrate metabolism (glucose) as the metabolic trigger.
According to ASPEN guidelines, which patient meets the criteria for HIGH risk of Refeeding Syndrome? A) BMI 18.5 with 5% weight loss in 1 month. B) BMI 15.5 with negligible intake for 12 days.
Show answer →Patient B is at high risk. ASPEN criteria for high risk include: BMI <16 kg/m2, unintentional weight loss >15% in 3-6 months, little or no nutritional intake for >10 days, or low baseline levels of potassium, phosphate, or magnesium. Patient A is considered moderate risk. Clinical Pearl: Always verify baseline electrolytes before initiating nutrition support in any patient meeting these malnutrition criteria to establish a safe starting point.
Why is thiamine supplementation prioritized BEFORE initiating nutrition support in patients at risk for Refeeding Syndrome?
Show answer →Thiamine (Vitamin B1) is a required co-factor for pyruvate dehydrogenase, the enzyme that converts pyruvate to acetyl-CoA for the Krebs cycle. Increased carbohydrate intake during refeeding increases the demand for thiamine. In a depleted state, this can lead to Wernicke’s Encephalopathy or lactic acidosis. Protocol: Administer 100-300mg thiamine IV or PO at least 30 minutes before feeding, then daily for 3-5 days. Exam Strategy: CDR emphasizes the sequence—thiamine first, then calories.
A dietitian monitors a patient during refeeding. Serum phosphorus drops from 3.0 mg/dL to 1.8 mg/dL within 24 hours. What is the immediate recommended action regarding the nutrition prescription?
Show answer →1) Reduce or hold calorie advancement. 2) Aggressively replace phosphorus (IV or PO depending on clinical severity). 3) Monitor electrolytes every 12 hours until stable. Rationale: Severe hypophosphatemia (<2.0 mg/dL) can lead to respiratory failure, cardiac arrhythmias, and death. Exam Tip: CDR expects you to know that slow and low applies to calorie titration, while fast and aggressive applies to electrolyte correction during the first 72-96 hours.
What is the clinical significance of sodium and fluid management during the first 3-5 days of refeeding in a severely malnourished patient?
Show answer →Insulin surge causes the kidneys to retain sodium and water (antinatriuretic effect). Over-aggressive feeding can lead to fluid overload, pulmonary edema, and heart failure (Wet Beriberi). Dietitians should limit initial fluid and sodium intake and monitor for rapid weight gain (>1kg/week is suspicious for fluid retention). CDR Focus: Distinguish between true weight gain (anabolism) vs. fluid shifts in the acute phase. Edema is a common physical sign of refeeding-induced fluid retention.
A patient with chronic pancreatitis presents with steatorrhea and night blindness. Which physiological process is most likely impaired, and how does this specifically affect the initial step of fat-soluble vitamin absorption?
Show answer →Absorption of fat-soluble vitamins (A, D, E, K) requires bile salts and pancreatic lipases for micelle formation. In chronic pancreatitis, lipase deficiency prevents the hydrolysis of triglycerides and retinyl esters. Without micelles, these vitamins cannot reach the brush border of the enterocytes for passive diffusion. CDR Tip: Distinguish between digestion (lipase) and absorption (micelle/diffusion). Distractors often mention the portal vein; remember, fat-soluble vitamins (except some K2) primarily enter the lymphatic system via chylomicrons.
A patient with Stage 4 Chronic Kidney Disease (CKD) has low serum calcium despite adequate cholecalciferol intake. What specific enzymatic step is impaired, and what is the resulting active metabolite required?
Show answer →The final step of Vitamin D activation (hydroxylation) occurs in the kidneys. The enzyme 1-alpha-hydroxylase converts 25(OH)D (calcidiol) into 1,25(OH)2D (calcitriol), the active hormone. In CKD, this enzyme is limited, leading to secondary hyperparathyroidism. RDN Exam Strategy: Remember that 25(OH)D is the marker for status, but 1,25(OH)2D is the physiologically active form that increases intestinal calcium absorption. Cholecalciferol (D3) is the precursor.
A patient taking Warfarin (Coumadin) begins high-dose Vitamin E supplementation (800 IU/day). What is the physiological mechanism behind the increased bleeding risk associated with this interaction?
Show answer →High doses of Vitamin E (specifically alpha-tocopherol) can inhibit Vitamin K-dependent carboxylase activity and interfere with the Vitamin K cycle. Specifically, Vitamin E quinone (a metabolite) may act as an anticoagulant by antagonizing Vitamin K's role in the gamma-carboxylation of clotting factors II, VII, IX, and X. CDR Focus: Always monitor Vitamin E intake in patients on anticoagulants. The UL for Vitamin E is 1,000 mg/day for adults due to this hemorrhagic risk.
A patient requires enteral nutrition for approximately 3 weeks due to resolving dysphagia post-stroke. Which access route is most appropriate according to current ASPEN guidelines?
Show answer →Nasogastric (NG) tube is the gold standard for short-term access (<4 weeks). It is non-invasive, cost-effective, and allows for bolus, intermittent, or continuous feeding. Exam Tip: CDR emphasizes using the GI tract whenever possible and starting with the most physiological route. Nasoduodenal or nasojejunal is only preferred if gastric emptying is severely delayed or aspiration risk is extremely high. NG is the primary choice for standard short-term needs.
A patient with severe gastroparesis and repeated aspiration pneumonia requires long-term EN (>6 weeks). Which access type is indicated to bypass the stomach while ensuring long-term stability?
Show answer →Percutaneous Endoscopic Jejunostomy (PEJ) or a Gastric-Jejunal (G-J) tube. PEJ is preferred for bypassing the stomach entirely to reduce aspiration risk. G-J tubes allow for gastric decompression while feeding into the jejunum. Exam Tip: For high aspiration risk, look for post-pyloric or jejunal options. Long-term (>4-6 weeks) always points to percutaneous (PEG/PEJ) or surgical routes over nasal (NG/NJ) routes.
A baker notices their cake has a coarse texture, a weak structure that easily crumbles, and a slightly soapy aftertaste. Which leavening-related error most likely occurred?
Show answer →The primary cause is an excess of baking soda (sodium bicarbonate). Excess soda increases the alkalinity (pH) of the batter, which weakens gluten strands and causes a coarse, open crumb. The soapy flavor results from the saponification of fats in the alkaline environment. CDR Exam Tip: Differentiate this from excess baking powder, which typically causes a metallic taste and can lead to a surface collapse after an initial over-expansion.
When preparing a recipe at an altitude of 5,000 feet, what modifications to chemical leavening agents and liquids are typically required to prevent cake collapse?
Show answer →At high altitudes, atmospheric pressure is lower, causing leavening gases to expand more rapidly before the protein structure sets. Strategy: 1) Decrease the amount of baking powder/soda to prevent over-expansion and subsequent collapse. 2) Increase liquid (water/milk) to compensate for the lower boiling point and increased evaporation rate. 3) Decrease sugar slightly to strengthen the structure by reducing its interference with gluten development.
A 55-year-old male is admitted for elective surgery. Which nutrition screening tool is most validated for use in the acute care setting due to its simplicity, focusing only on recent weight loss and appetite changes?
Show answer →The Malnutrition Screening Tool (MST) is the most appropriate. It is highly validated for the acute care setting and is recommended by the Academy of Nutrition and Dietetics. It consists of two questions: 1) Have you lost weight recently without trying? 2) Have you been eating poorly because of a decreased appetite? A score of 2 or more indicates nutritional risk. CDR Tip: MST is often favored in fast-paced clinical settings because it does not require objective measurements like height or weight to initiate the screening process.
A patient on Warfarin begins a green smoothie challenge, consuming 3 cups of spinach daily. Their INR drops from 2.5 to 1.4. What is the primary pathophysiological reason and RDN recommendation?
Show answer →Warfarin inhibits Vitamin K epoxide reductase, preventing the recycling of Vitamin K. High Vitamin K intake provides more substrate for clotting factor synthesis (II, VII, IX, X), antagonizing the drug. RDN Recommendation: Do NOT stop the spinach; instead, maintain a consistent daily intake. The medical team will adjust the Warfarin dose to match this new stable intake. CDR Exam Tip: Avoidance is an incorrect distractor; consistency is the gold standard for Warfarin counseling.
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.
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