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?

1 Serum creatinine increased from baseline 0.8 to 1.3 mg/dL within 48 hours ✓ Correct answer
2 Urine specific gravity 1.025
3 Serum sodium 138 mEq/L
4 BUN 22 mg/dL

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 <0.5 mL/kg/h for 6-12 h. Stage 2: 2-2.9x or UOP for ≥12 h. Stage 3: ≥3x or RRT.
Prerenal AKI — AKI from decreased renal perfusion (hypovolemia, hypotension, heart failure, NSAIDs). Reversible if corrected early. Lab pattern: BUN/creatinine ratio >20:1, FENa <1%, concentrated urine. Treat with volume restoration.
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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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?

In-depth explanation

Clinical scenario

Key concepts

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