DACBN common mistakes
DACBN · Understand the traps and how to avoid them.
Calculating a patient's protein or calorie target from actual body weight when the vignette gives a BMI above 30, instead of selecting an adjusted, ideal, or per-kg-of-ideal body weight approach the question is testing.
Candidates memorize a single '1.2-1.5 g/kg' figure and apply it reflexively, so they never pause to check which weight basis the item is probing; the arithmetic then lands on a distractor that was deliberately built from actual weight.
What to do instead
Before doing any arithmetic, write the weight basis you are using in one word (actual, ideal, adjusted, or per-kg-of-ideal) and check the BMI in the stem. Practice a 10-item set where the only variable is weight basis, and confirm each answer by re-deriving from the stated basis rather than the first number that matches an option.
Choosing the feeding route or formula by diagnosis label (e.g., 'pancreatitis, so jejunal') without checking the functional status details the stem supplies, such as aspiration risk, gastric residuals, hemodynamic stability, or whether the gut is working.
Exam stems front-load a diagnosis, and candidates pattern-match diagnosis to route from memory rather than reading the subsequent clinical details that are there to override the reflex; item writers exploit exactly this shortcut.
What to do instead
Read the last sentence of the stem first to see what is actually being asked, then scan for the three or four override cues (aspiration, ileus, shock, fistula location). Build a one-page decision table of route triggers and rehearse it until you can state which single finding would change your answer.
Treating refeeding syndrome risk as binary, giving a full-calorie start to a patient with low BMI, recent weight loss, low phosphate, or little oral intake for days, and only considering risk when the stem says 'refeeding' explicitly.
Candidates learn refeeding as a named complication and wait for the word to appear, missing that the item is testing risk stratification from risk factors; the distractor is always 'start at goal rate.'
What to do instead
Memorize the four or five risk criteria and the corresponding start-low, go-slow, thiamine-before-feed, and electrolyte-repletion sequence. On every nutrition-support item, run a five-second risk screen before choosing a start rate, and practice items where refeeding is never named.
Confusing the indication for parenteral nutrition with the indication for enteral nutrition, selecting PN for a patient whose gut is functional but whose intake is poor, or selecting EN for a patient with an absolute contraindication such as bowel ischemia or high-output fistula.
Both routes are 'nutrition support,' so candidates collapse them into one category and pick whichever sounds more aggressive or more physiologic, rather than applying the 'if the gut works, use it' rule against absolute contraindications.
What to do instead
Write out the absolute contraindications to EN and the indications for PN as two separate lists and compare them side by side. For each practice item, state aloud whether the gut is functional and whether EN is contraindicated before looking at the options.
Estimating energy needs with a simple 25-30 kcal/kg rule when the stem supplies enough data (age, sex, weight, height, activity, stress factor) to compute a predictive equation, or conversely performing a full equation when the item expects a clinical estimate.
Candidates do not know which method the exam favors in which context, so they default to the formula they remember most fluently and ignore the cue in the stem about which method is being tested.
What to do instead
Learn to recognize the cue: when the stem gives all equation inputs, compute; when it gives a stress state and asks for a range, estimate. Do a mixed set of ten items and label each as 'compute' or 'estimate' before answering, then check that your chosen number falls inside the expected range.
Managing a micronutrient deficiency by repleting the deficient nutrient alone while ignoring the cofactor or opposing electrolyte that the clinical picture implicates, such as giving potassium without magnesium in refractory hypokalemia or giving calcium without correcting vitamin D and phosphate.
The stem names one abnormal lab value, and candidates anchor on that value alone; the item is testing whether they understand the interdependence of electrolytes and micronutrients, which is easy to skip under time pressure.
What to do instead
Build a short interdependence map (magnesium-potassium, vitamin D-calcium-phosphate, thiamine-glucose load, copper-zinc balance) and review it before each practice block. When a lab value is abnormal, ask what else must be checked before treating, and choose the option that reflects that pairing.
Reading a nutrition-assessment item as a single-test question and picking the 'best lab test' when the stem is actually testing the value of a composite assessment, or the reverse, choosing a global tool when a specific validated screening instrument is being asked about.
Candidates conflate screening with assessment and laboratory markers with clinical judgment, so they pick the most familiar named tool or the most abnormal lab rather than matching the tool to the question's purpose.
What to do instead
Separate the two concepts explicitly: screening identifies risk, assessment establishes diagnosis and plan. Memorize which instruments are screening tools and which are full assessments, and for each practice item state the purpose of the tool before selecting it.
Ignoring the drug-nutrient interaction embedded in the medication list, such as a patient on warfarin being advised a high-vitamin-K diet change, or a patient on a proton-pump inhibitor or metformin whose micronutrient risk the item is testing.
The medication list reads as background context, and candidates skim it looking for the nutrition problem; item writers place the decisive clue there precisely because it looks like filler.
What to do instead
Make reading the medication list a mandatory step before evaluating nutrition options, and keep a short list of high-yield interactions (vitamin K and warfarin, PPIs and B12/magnesium, metformin and B12, corticosteroids and glucose/calcium). Practice by covering the options and predicting the interaction from the med list alone.
Applying adult thresholds and formulas to pediatric or neonatal patients, or using the same growth-chart interpretation for a preterm infant as for a term infant, because the candidate studies adult nutrition almost exclusively.
Pediatric content is a small fraction of most study plans, so candidates default to adult norms; the item's age in months or corrected gestational age is the tell they overlook.
What to do instead
Create a dedicated pediatric and neonatal summary covering fluid and calorie needs by age band, corrected age, growth-chart selection, and fortification decisions. Do a timed block of pediatric-only items and force yourself to state the age band and chart type before answering.
Answering monitoring questions with the baseline or diagnostic test rather than the follow-up parameter the intervention actually changes, such as ordering a repeat baseline lab instead of the electrolyte or glycemic marker that the started therapy affects.
Candidates memorize which test diagnoses a condition but not which test monitors a treatment, and under time pressure they pick the test they associate most strongly with the disease name.
What to do instead
For every major intervention, write the one parameter you would check and the timeframe. Drill paired items that ask 'diagnose' versus 'monitor' for the same condition, and confirm your answer names a parameter that the intervention plausibly changes within the stated interval.