A 79-year-old client is admitted from a long-term care facil… | MyMerci
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Medical EmergenciesPA
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?
1Urine specific gravity increased from 1.005 to 1.025 over 24 hours
2Blood urea nitrogen increased from 10 to 22 mg/dL over 72 hours
3Serum sodium level decreased from 140 to 138 mEq/L in 48 hours
4Serum creatinine increased from baseline 0.8 to 1.3 mg/dL within 48 hours✓ Correct answer
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.
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.