# A 79-year-old client is admitted from a long-term care facility with diarrhea, decreased oral intake, and concentrated dark urine for 3 days. The nurse reviews recent labs. Which finding most concerns the nurse for early acute kidney injury and warrants immediate provider notification?

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> url: https://mymerci.kr/pages/nclex_q.php?qn_id=363089&lang=en  
> language: en  
> subject: Medical Emergencies  
> category: PA

## Question

A 79-year-old client is admitted from a long-term care facility with diarrhea, decreased oral intake, and concentrated dark urine for 3 days. The nurse reviews recent labs. Which finding most concerns the nurse for early acute kidney injury and warrants immediate provider notification?

## Option

1. Urine specific gravity increased from 1.005 to 1.025 over 24 hours
2. Blood urea nitrogen increased from 10 to 22 mg/dL over 72 hours
3. Serum sodium level decreased from 140 to 138 mEq/L in 48 hours
4. Serum creatinine increased from baseline 0.8 to 1.3 mg/dL within 48 hours **✔ Correct answer**

**Correct answer: 4**

## Explanation

KDIGO Stage 1 acute kidney injury: rise in serum creatinine of 0.3 mg/dL or more within 48 hours, OR 1.5 to 1.9 times baseline within 7 days, OR urine output below 0.5 mL/kg/hour for 6 to 12 hours. A creatinine increase from 0.8 to 1.3 mg/dL within 48 hours (delta 0.5) meets KDIGO Stage 1 in this dehydrated older adult. Specific gravity 1.025 and BUN 22 reflect dehydration alone. Sodium 138 mEq/L is within normal limits.

## In-depth explanation

Clinical Judgment
Older adults often have a low baseline creatinine due to reduced muscle mass, so even modest absolute rises represent significant GFR loss. KDIGO Stage 1 AKI: creatinine rise ≥0.3 mg/dL within 48 h OR 1.5-1.9× baseline in 7 d. The 0.5 mg/dL increase here is the earliest actionable signal.

Memory Tip
AKI: 0.3 in 48 h, 1.5x in 7 d, or UOP <0.5 mL/kg/h for 6 h

KR vs US
KDIGO is the unified global standard. Korea uses identical staging in clinical practice and exam content. NCLEX expects KDIGO criteria, not older RIFLE classes.

## Clinical scenario

Clinical Practice Guide
KDIGO 2012 AKI staging:
- Stage 1: creatinine increase ≥0.3 mg/dL in 48 h or 1.5-1.9× baseline in 7 d, OR UOP <0.5 mL/kg/h for 6-12 h
- Stage 2: 2.0-2.9× baseline OR UOP <0.5 mL/kg/h for ≥12 h
- Stage 3: ≥3× baseline, creatinine ≥4.0, RRT initiation, or UOP <0.3 mL/kg/h ≥24 h
Initial intervention for prerenal AKI: isotonic IV fluid resuscitation, hold nephrotoxins (NSAIDs, ACE-I, contrast).

Caution
Older adults have lower baseline creatinine due to reduced muscle mass — even small rises matter. Always compare to baseline, not absolute value. A rise from 0.8 to 1.3 in a frail elderly client may represent >50% loss of GFR.

## Key concepts

- **KDIGO AKI staging** — Kidney Disease: Improving Global Outcomes 2012 staging system. Stage 1: creatinine 1.5-1.9x baseline or rise ≥0.3 mg/dL in 48 h, OR UOP
- **Prerenal AKI** — AKI from decreased renal perfusion (hypovolemia, hypotension, heart failure, NSAIDs). Reversible if corrected early. Lab pattern: BUN/creatinine ratio >20:1, FENa
- **Baseline creatinine** — A clients usual serum creatinine before the current illness. Older adults often have a low baseline (0.6-0.8) because of reduced muscle mass; small absolute increases can still represent large GFR loss. Always trend, not the single value.

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