An NCLEX case study, worked in full
Not a description of a case study — an actual one. Work each step before revealing it.
Below is one complete unfolding case from the PrepScore bank — "ABG Cascade — Mixed Disorder to Bedside Action" — exactly as the product presents it: one client, 5 items that build on each other, each in a real Next Gen format and each tagged to the clinical judgment step it tests. Answers are behind reveals, so you can work it before reading it. On the exam, clinical judgment is measured by case study items of exactly this unfolding shape.
The client
44-yo M T1DM brought to ED unresponsive at home; mother says he stopped insulin pump 2 days ago. RR 32 + deep. Glucose 542, ketones large. Initial ABG + chemistry → identify primary disorder + compensation + anion gap → action → recheck after Rx.
Step 1 — ED arrival — labs in
ED arrival — labs in
- AG
- 30
- ABG
- pH 7.18 · HCO3 8 · PaO2 98 · PaCO2 22
- chem
- K 5.8 · Cl 96 · Na 134 · glucose 542 · ketones large
- patient
- hx T1DM × 22 yr, insulin pump · age 44 · sex M · trigger stopped pump 2 days ago
Identify each value as ABNORMAL + DIRECTION or as WITHIN NORMAL.
| Finding | Abnormal (note direction) | Normal |
|---|---|---|
| pH 7.18 (normal 7.35-7.45) — ACIDEMIA | ○ | ○ |
| PaCO2 22 mmHg (normal 35-45) — LOW (hyperventilation / respiratory response) | ○ | ○ |
| HCO3 8 mEq/L (normal 22-26) — LOW (metabolic acidosis) | ○ | ○ |
| Na 134, Cl 96, glucose 542, ketones large | ○ | ○ |
| Anion gap = Na - (Cl + HCO3) = 134 - (96 + 8) = 30 (HIGH; normal ~8-12) — HIGH ANION GAP | ○ | ○ |
| K 5.8 (normal 3.5-5.0) — HIGH (DKA depletes total body K but extracellular shift from acidosis raises serum) | ○ | ○ |
| PaO2 98 on room air — NORMAL | ○ | ○ |
| Temperature 37.0°C — NORMAL | ○ | ○ |
Show answer and rationale
- PaO2 98 on room air — NORMAL → Normal
- Temperature 37.0°C — NORMAL → Normal
- pH 7.18 (normal 7.35-7.45) — ACIDEMIA → Abnormal (note direction)
- Na 134, Cl 96, glucose 542, ketones large → Abnormal (note direction)
- HCO3 8 mEq/L (normal 22-26) — LOW (metabolic acidosis) → Abnormal (note direction)
- PaCO2 22 mmHg (normal 35-45) — LOW (hyperventilation / respiratory response) → Abnormal (note direction)
- Anion gap = Na - (Cl + HCO3) = 134 - (96 + 8) = 30 (HIGH; normal ~8-12) — HIGH ANION GAP → Abnormal (note direction)
- K 5.8 (normal 3.5-5.0) — HIGH (DKA depletes total body K but extracellular shift from acidosis raises serum) → Abnormal (note direction)
ABG step-wise: (1) pH < 7.35 = acidemia; (2) which is moving with pH? HCO3 ↓ → METABOLIC ACIDOSIS primary; (3) PaCO2 also ↓ → respiratory COMPENSATION (Winter's: expected PaCO2 = 1.5×HCO3 + 8 ± 2 = 1.5×8+8 = 20 ± 2 ≈ 22 ✓ APPROPRIATE compensation, not separate respiratory disorder); (4) Anion gap = Na-(Cl+HCO3) = 30 = HIGH (MUDPILES — methanol, uremia, DKA, propylene glycol, INH/iron, lactic, ethylene glycol, salicylates); (5) Hyperkalemia from acidotic shift (total body K is DEPLETED).
Step 2 — Acid-base + DKA categorization
Acid-base + DKA categorization
- interpretation
- HAGMA from DKA with appropriate respiratory compensation; K 5.8 supports starting insulin
Choose the correct interpretation.
1. [BLANK1] 2. [BLANK2] 3. [BLANK3] 4. [BLANK4] 5. [BLANK5]
- respiratory acidosis
- HIGH ANION GAP METABOLIC ACIDOSIS (HAGMA) — primary
- metabolic alkalosis
- respiratory alkalosis
- no compensation
- RESPIRATORY COMPENSATION — appropriate (Winter's: PaCO2 ≈ 1.5×HCO3+8)
- respiratory acidosis added
- metabolic alkalosis added
- narrow anion gap
- ELEVATED ANION GAP — ketones (DKA) consume HCO3 + raise unmeasured anions
- anion gap is irrelevant
- low anion gap
- Salicylate toxicity
- DKA — T1DM + stopped insulin + glucose 542 + large ketones + HAGMA
- Methanol
- Uremia
- replete K aggressively first
- K LEVEL DRIVES INSULIN TIMING — K >5.2: start fluids + insulin; K 3.3-5.2: insulin + K in fluids; K <3.3: HOLD insulin + replete K FIRST (insulin drops K dangerously)
- no K monitoring needed
- give insulin regardless
Show answer and rationale
- BLANK1: HIGH ANION GAP METABOLIC ACIDOSIS (HAGMA) — primary
- BLANK2: RESPIRATORY COMPENSATION — appropriate (Winter's: PaCO2 ≈ 1.5×HCO3+8)
- BLANK3: ELEVATED ANION GAP — ketones (DKA) consume HCO3 + raise unmeasured anions
- BLANK4: DKA — T1DM + stopped insulin + glucose 542 + large ketones + HAGMA
- BLANK5: K LEVEL DRIVES INSULIN TIMING — K >5.2: start fluids + insulin; K 3.3-5.2: insulin + K in fluids; K <3.3: HOLD insulin + replete K FIRST (insulin drops K dangerously)
Interpretation: HAGMA from DKA with appropriate respiratory compensation (Kussmaul respirations = hyperventilation lowering PaCO2). MUDPILES list: M-methanol, U-uremia, D-DKA, P-propylene glycol, I-INH/iron/ingestion, L-lactic acidosis, E-ethylene glycol, S-salicylates. K management: ADA DKA guideline — if K <3.3, HOLD insulin + give K (insulin will worsen hypokalemia → arrhythmia); K 3.3-5.2 = add K to fluids; K >5.2 = start insulin + monitor.
Step 3 — DKA treatment sequence
DKA treatment sequence
- order
- fluids → insulin → K maintenance → D5 added → transition
Place these DKA interventions in the CORRECT order of initiation.
- Transition to subcutaneous basal-bolus insulin once AG closed + pt eating (overlap 1-2h)
- Switch IV fluids to D5-containing solution when glucose ~200 to prevent hypoglycemia + allow continued insulin for ketone clearance
- Start regular insulin IV infusion 0.1 unit/kg/h (no bolus per current ADA) IF K ≥3.3
- ABCs + IV access + cardiac monitor + identify K level
- Initiate aggressive isotonic fluid resuscitation (NS 15-20 mL/kg in first hour) — DEFICIT often 5-10 L
Show answer and rationale
- ABCs + IV access + cardiac monitor + identify K level
- Initiate aggressive isotonic fluid resuscitation (NS 15-20 mL/kg in first hour) — DEFICIT often 5-10 L
- Start regular insulin IV infusion 0.1 unit/kg/h (no bolus per current ADA) IF K ≥3.3
- Switch IV fluids to D5-containing solution when glucose ~200 to prevent hypoglycemia + allow continued insulin for ketone clearance
- Transition to subcutaneous basal-bolus insulin once AG closed + pt eating (overlap 1-2h)
DKA treatment sequence (ADA): (1) ABCs + IV + monitor + K identified; (2) Fluids FIRST (volume deficit huge; 15-20 mL/kg in hr 1; transition to 0.45% NaCl based on corrected Na); (3) Insulin infusion (only after K confirmed ≥3.3); (4) Switch to D5 fluids when glucose ~200 to keep insulin running until AG closed (treats ketosis, not glucose); (5) Transition to SC basal-bolus when AG closed + bicarb improving + pt eating, OVERLAP 1-2h with infusion. Bicarbonate ONLY for pH <6.9 (controversial).
Step 4 — First 2h actions
First 2h actions
- first 2h
- NS bolus + insulin 0.1 u/kg/h + hourly K + cardiac monitor + screening for trigger
Classify each action as APPROPRIATE or INAPPROPRIATE in this DKA presentation.
| Finding | APPROPRIATE | INAPPROPRIATE |
|---|---|---|
| Initiate isotonic NS 15-20 mL/kg in first hour | ○ | ○ |
| Start insulin infusion 0.1 unit/kg/h (K is 5.8, safe to start) | ○ | ○ |
| Monitor K hourly + add K to fluids once K drops below 5.2 | ○ | ○ |
| Hourly glucose + AG / electrolytes / VBG q2-4h | ○ | ○ |
| Bolus IV bicarbonate 50 mEq for pH 7.18 (NOT — bicarb reserved for pH <6.9 / hemodynamic instability) | ○ | ○ |
| Cardiac monitor — watch for hyperK changes (peaked T) at presentation + hypoK changes (U waves) as insulin drives K in | ○ | ○ |
| Search for precipitant — pump malfunction, infection, missed insulin, MI, pregnancy | ○ | ○ |
| Treat suspected infection empirically while culturing | ○ | ○ |
| Give DKA pt D5W as initial fluid (NOT — glucose is 542, needs NS not dextrose) | ○ | ○ |
| Pt + family education on sick-day rules + pump management once stable | ○ | ○ |
Show answer and rationale
- Hourly glucose + AG / electrolytes / VBG q2-4h → APPROPRIATE
- Initiate isotonic NS 15-20 mL/kg in first hour → APPROPRIATE
- Treat suspected infection empirically while culturing → APPROPRIATE
- Monitor K hourly + add K to fluids once K drops below 5.2 → APPROPRIATE
- Start insulin infusion 0.1 unit/kg/h (K is 5.8, safe to start) → APPROPRIATE
- Pt + family education on sick-day rules + pump management once stable → APPROPRIATE
- Give DKA pt D5W as initial fluid (NOT — glucose is 542, needs NS not dextrose) → INAPPROPRIATE
- Search for precipitant — pump malfunction, infection, missed insulin, MI, pregnancy → APPROPRIATE
- Bolus IV bicarbonate 50 mEq for pH 7.18 (NOT — bicarb reserved for pH <6.9 / hemodynamic instability) → INAPPROPRIATE
- Cardiac monitor — watch for hyperK changes (peaked T) at presentation + hypoK changes (U waves) as insulin drives K in → APPROPRIATE
DKA bundle: fluids, insulin, K, frequent monitoring. AVOID: bicarb (not for pH ≥6.9 — no outcome benefit, paradoxical CSF acidosis, hypoK), early dextrose-containing fluids when glucose still high (defeats purpose). Watch K transitions: hyperK at presentation → hypoK once insulin starts shifting K intracellularly. Find + treat precipitant. Sick-day education for prevention.
Step 5 — Reassess after 12h treatment
Reassess after 12h treatment
- education
- sick-day rules + pump troubleshooting + mental health
- resolution
- AG closed at 12h
- transition
- SC insulin started with overlap
Repeat labs at 12h. Match outcomes + ongoing plan.
- Transition to SC basal-bolus insulin with 1-2h overlap once AG closed + bicarb ≥18 + eating
- Stop insulin abruptly
- Discharge home now
- pH 7.33, HCO3 18, AG 14 (closing) → DKA RESOLVING
- Glucose 180 on D5 + insulin infusion
- K 4.0 (replacement working — total body K still depleted)
- Pt alert + tolerating PO fluids
- Precipitant identified: pump occlusion + recent URI
- Sick-day rules education + ketone testing + pump troubleshooting + 'never stop insulin' counseling
- Endocrine + diabetes educator follow-up within 1 week
- MedicAlert + glucagon Rx + emergency contacts
- Mental health screening (T1DM + DKA recurrence often depression/burnout)
- Discharge with no follow-up
Show answer and rationale
- transition step: Transition to SC basal-bolus insulin with 1-2h overlap once AG closed + bicarb ≥18 + eating
- resolution evidence: pH 7.33, HCO3 18, AG 14 (closing) → DKA RESOLVING; Glucose 180 on D5 + insulin infusion; K 4.0 (replacement working — total body K still depleted); Pt alert + tolerating PO fluids; Precipitant identified: pump occlusion + recent URI
- prevention long term: Sick-day rules education + ketone testing + pump troubleshooting + 'never stop insulin' counseling; Endocrine + diabetes educator follow-up within 1 week; MedicAlert + glucagon Rx + emergency contacts; Mental health screening (T1DM + DKA recurrence often depression/burnout)
DKA RESOLUTION criteria: glucose <200, AG closed (≤12), HCO3 ≥18, pH ≥7.30, pt eating. Transition to SC insulin with 1-2h OVERLAP (stopping insulin too soon = rebound DKA). Long-term: sick-day rules ('never stop insulin'), ketone testing at home, pump troubleshooting, endocrine + DM educator, mental health screening (T1DM burnout + depression common in recurrent DKA), MedicAlert + glucagon Rx.
What to notice
- The information unfolds. What you established at step 1 still governs step 4 — which is what a case study tests and a stand-alone item cannot.
- The formats change between steps. Matrix, ordering, select-N: the case uses whichever format fits the decision, exactly as the exam does.
- Each step is scored on its own, and most formats award partial credit per element.
Work the other 52 cases
Every case is tagged by clinical judgment step, so your case work builds the same six-step profile as everything else.
Frequently asked questions
Is this a real NCLEX case study?
It is a real unfolding case from the PrepScore bank, built in the Next Gen shape the exam uses — one client, unfolding information, items in the real formats. It is practice material, not a leaked exam item.
How many case studies does the exam include?
NCSBN's test plan states that clinical judgment is measured by 18 case study items — three sets of six — plus stand-alone items depending on exam length.
How should I practise case studies?
In one sitting per case, not as loose questions. The skill being tested is whether earlier reasoning survives to later items — see the case studies guide.
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