# Situation: A 58-year-old man with type 2 diabetes mellitus and severe peripheral arterial disease of the left leg has had a nonhealing ulcer over the left heel for 2 months. Magnetic resonance imaging (MRI) shows osteomyelitis of the calcaneus. He receives intravenous vancomycin. Per unit protocol, the target trough level is 15–20 mg/L, and a creatinine rise of 50% or more from baseline is reported. Normal serum creatinine: 0.7–1.3 mg/dL (62–115 µmol/L). Day 1: creatinine 0.7 mg/dL (62 µmol/L) Day 3: trough 14 mg/L; creatinine 0.8 mg/dL (71 µmol/L) Day 6: trough 18 mg/L; creatinine 1.2 mg/dL (106 µmol/L) Which action should the nurse take before the day 6 evening dose?

> source: MyMerci (mymerci.kr)  
> url: https://mymerci.kr/pages/nclex_q.php?qn_id=630532  
> language: ko  
> subject: Nursing Practice IV — Care of Clients with Problems in Nutrition and Gastrointestinal, Metabolism and Endocrine, Perception and Coordination

## 문제

Situation: A 58-year-old man with type 2 diabetes mellitus and severe peripheral arterial disease of the left leg has had a nonhealing ulcer over the left heel for 2 months. Magnetic resonance imaging (MRI) shows osteomyelitis of the calcaneus.

He receives intravenous vancomycin. Per unit protocol, the target trough level is 15–20 mg/L, and a creatinine rise of 50% or more from baseline is reported. Normal serum creatinine: 0.7–1.3 mg/dL (62–115 µmol/L).
Day 1: creatinine 0.7 mg/dL (62 µmol/L)
Day 3: trough 14 mg/L; creatinine 0.8 mg/dL (71 µmol/L)
Day 6: trough 18 mg/L; creatinine 1.2 mg/dL (106 µmol/L)
Which action should the nurse take before the day 6 evening dose?

## 보기

1. Hold this dose and recheck the creatinine tomorrow
2. Report the creatinine before giving this dose **✔ 정답**
3. Give the dose, as creatinine is still within normal
4. Give the dose and recheck the trough in a week

**정답: 2**

## 해설

Vancomycin is nephrotoxic and cleared by the kidneys. Creatinine has risen from 0.7 to 1.2 mg/dL, about 71% above baseline, which signals acute kidney injury even though the value is still inside the normal range; the prescriber must review before the next dose.

## 심화 해설

Look at the trend, not only the normal range
Vancomycin is a nephrotoxic drug cleared by the kidneys, so kidney function is watched closely throughout therapy. The protocol in this unit says to report a creatinine rise of 50% or more from baseline. His baseline on day 1 was 0.7 mg/dL (62 µmol/L). By day 6 it is 1.2 mg/dL (106 µmol/L). The rise is 0.5 mg/dL, and 0.5 divided by 0.7 is about 71%. A creatinine that is still inside the normal range can still represent acute kidney injury when it has risen sharply from the client's own baseline. That is why the nurse reports before the next dose.

Why the rise matters with this drug
Because vancomycin is removed by the kidneys, falling kidney function lets the drug accumulate, which raises levels and causes further kidney injury in a cycle. His trough has also climbed from 14 mg/L on day 3 to 18 mg/L on day 6. The trough is still in the target range of 15–20 mg/L, but the rising creatinine signals that clearance may be falling and the next levels may exceed the target. The prescriber, often with the pharmacist, decides whether to hold, reduce, or space out the dose.

| Day | Creatinine | Change from baseline | Trough |
| --- | --- | --- | --- |
| 1 | 0.7 mg/dL | Baseline | – |
| 3 | 0.8 mg/dL | About 14% | 14 mg/L |
| 6 | 1.2 mg/dL | About 71% | 18 mg/L |

Why the other actions are wrong
Holding the dose and rechecking tomorrow means the nurse independently changes a scheduled antibiotic without informing the prescriber; the rise must be reported so the regimen can be adjusted. Giving the dose because the creatinine is "still normal" ignores the protocol and the client's baseline. Giving the dose and waiting a week to recheck the trough ignores kidney injury that is already present.

Nursing monitoring on vancomycin
The nurse tracks creatinine, urine output, and trough levels, avoids other nephrotoxic drugs when possible, ensures adequate hydration, infuses the drug slowly to prevent infusion reaction (flushing of the upper body), and watches for ototoxicity. In older adults and in clients with diabetes, kidney function can fall quickly.

Exam takeaway
Watch out A lab value in the normal range is not automatically safe. Compare with the baseline and follow the reporting rule before giving a nephrotoxic drug.

## 임상 시나리오

Vancomycin and Rising CreatinineBaseline comparison before a dose
Vancomycin is nephrotoxic and cleared by the kidneys. The protocol says to report a creatinine rise of 50% or more from baseline.

Creatinine rose from 0.7 to 1.2 mg/dL, about 71%, even though it is still inside the normal range. This signals acute kidney injury.

Report before the evening dose so the prescriber can adjust the regimen. Keep tracking urine output, creatinine, and trough levels.

CautionDo not hold or change a scheduled antibiotic on your own, and do not give it simply because the value looks normal. Report first.

## 핵심 개념

- **Nephrotoxicity** — Damage to the kidneys caused by a drug or toxin, often detected by a rising creatinine.
- **Trough level** — The lowest drug concentration, measured just before the next dose.
- **Baseline** — A client's starting value used for comparison when judging later changes.
- **Acute kidney injury** — A sudden fall in kidney function shown by rising creatinine or falling urine output.

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