# Situation: A 62-year-old woman with breast cancer that has spread to her bones is admitted with confusion, constipation, thirst, and passing large amounts of urine. Her mucous membranes are dry. Her serum calcium is 13.6 mg/dL (3.39 mmol/L) (8.6–10.2 mg/dL; 2.15–2.55 mmol/L), and her albumin is 3.8 g/dL (38 g/L). After 24 hours of treatment, the physician orders zoledronic acid IV. Before starting it, the nurse reviews her results: Calcium: 12.4 mg/dL (3.09 mmol/L) (8.6–10.2 mg/dL) Potassium: 3.4 mEq/L (3.5–5.0 mEq/L) Serum creatinine: 1.9 mg/dL (168 µmol/L) (0.6–1.2 mg/dL) Magnesium: 1.8 mg/dL (1.7–2.2 mg/dL) What should the nurse do?

> source: MyMerci (mymerci.kr)  
> url: https://mymerci.kr/pages/nclex_q.php?qn_id=629905  
> language: ko  
> subject: Nursing Practice III — Care of Clients with Problems in Surgery, Oxygenation, Fluid and Electrolytes, Infectious, Inflammatory and Immunologic Response, Cellular Aberrations

## 문제

Situation: A 62-year-old woman with breast cancer that has spread to her bones is admitted with confusion, constipation, thirst, and passing large amounts of urine. Her mucous membranes are dry. Her serum calcium is 13.6 mg/dL (3.39 mmol/L) (8.6–10.2 mg/dL; 2.15–2.55 mmol/L), and her albumin is 3.8 g/dL (38 g/L).

After 24 hours of treatment, the physician orders zoledronic acid IV. Before starting it, the nurse reviews her results:
Calcium: 12.4 mg/dL (3.09 mmol/L) (8.6–10.2 mg/dL)
Potassium: 3.4 mEq/L (3.5–5.0 mEq/L)
Serum creatinine: 1.9 mg/dL (168 µmol/L) (0.6–1.2 mg/dL)
Magnesium: 1.8 mg/dL (1.7–2.2 mg/dL)
What should the nurse do?

## 보기

1. Hold the infusion until her low potassium has been replaced
2. Report the creatinine before starting the infusion **✔ 정답**
3. Start the infusion, since her calcium is still well above normal
4. Start the infusion and recheck her calcium level in 6 hours

**정답: 2**

## 해설

Zoledronic acid is cleared by the kidneys and can injure them, so kidney function is checked before each dose. Her creatinine of 1.9 mg/dL (168 µmol/L) is above normal, so the nurse reports it before starting; the physician may delay the dose, give more fluid first, or confirm that the benefit outweighs the risk. Her high calcium is the reason for the drug but does not override the kidney check, and a potassium of 3.4 mEq/L is not a reason to hold a bisphosphonate.

## 심화 해설

Core issue: Zoledronic acid is nephrotoxic, so renal function must be verified before each dose.

Zoledronic acid is a potent intravenous bisphosphonate used to treat hypercalcemia of malignancy and bone metastases. It is cleared primarily by the kidneys, and renal deterioration is recognized as the most significant toxicity associated with zoledronic acid [1]. Unlike oral bisphosphonates, which are not typically linked to meaningful nephrotoxicity, IV bisphosphonates carry a dose-dependent and infusion time-dependent risk of kidney injury [3]. Because of this, a serum creatinine level must be reviewed before each infusion is given.

In this patient, the serum creatinine is 1.9 mg/dL (168 µmol/L), which is above the reference range of 0.6–1.2 mg/dL. This is an important finding. The physician needs to know about this decline in renal function before the zoledronic acid is administered. Depending on the clinical picture, the physician may choose to delay the dose, provide additional IV hydration first, adjust the dose, or confirm that the expected benefit still outweighs the renal risk. The nurse should not independently start the infusion when creatinine is elevated without first reporting it.

Watch out! The calcium of 12.4 mg/dL (3.09 mmol/L) is still high, but that does not override the renal safety check. Hypercalcemia is the indication for the drug, not a reason to bypass the creatinine review. The potassium of 3.4 mEq/L is only mildly low and is not a contraindication to bisphosphonate therapy; it does not require correction before the infusion. The magnesium of 1.8 mg/dL is within normal limits.

Renal function monitoring is not a one-time step. Studies evaluating zoledronic acid in oncology patients have tracked serum creatinine at baseline, during treatment, and at peak levels because renal impairment can emerge over time [4]. In addition, zoledronic acid has been associated with both hypocalcemia and elevated serum creatinine in cancer patients, reinforcing the need to assess electrolytes and renal status together [2]. For this patient, the immediate priority is to report the elevated creatinine before starting the infusion.

| Laboratory value | Result | Clinical relevance before zoledronic acid |
| --- | --- | --- |
| Serum calcium | 12.4 mg/dL | Still elevated; indicates ongoing need for treatment but does not bypass renal check |
| Serum creatinine | 1.9 mg/dL | Elevated; must be reported because zoledronic acid is nephrotoxic and renally cleared |
| Potassium | 3.4 mEq/L | Mildly low; not a reason to hold a bisphosphonate |
| Magnesium | 1.8 mg/dL | Normal; no action needed |

Key point! Before each zoledronic acid dose, verify serum creatinine and report any elevation above baseline or normal range. The drug’s nephrotoxicity is both dose-dependent and infusion time-dependent, so renal status directly influences whether the dose should be given, delayed, or modified [3].References (research sources)

- [1]Impact of zoledronic acid on renal function in patients with cancer: Clinical significance and development of a predictive model.Research articleMcDermott RS, Kloth DD, Wang H, Hudes GR, Langer CJ (2006)

- [2]Zoledronic Acid-Related Hypocalcemia and Renal Dysfunction in Oncology Patients: A Tertiary Care Experience.Research articleJamil MA, Majeed MA, Ali M, Asif H, Imran M, Imran M, Aslam S, Qureshi O, Ul Ain N, Bano S, Sadique N, Ali F, Bin Naeem S. (2025) · DOI: 10.7759/cureus.98055

- [3]Bisphosphonate nephrotoxicity.Research articlePerazella MA, Markowitz GS (2008) · DOI: 10.1038/ki.2008.356

- [4]Assessment of renal toxicity and osteonecrosis of the jaws in patients receiving zoledronic acid for bone metastasis.Research articleAguiar Bujanda D, Bohn Sarmiento U, Cabrera Suárez MA, Aguiar Morales J (2007) · DOI: 10.1093/annonc/mdl408

## 임상 시나리오

Zoledronic Acid Pre-Infusion Safety CheckRenal function must be verified before every dose
Zoledronic acid is nephrotoxic and is cleared primarily by the kidneys. A serum creatinine must be reviewed before each infusion. A creatinine of 1.9 mg/dL (168 µmol/L) is above the reference range of 0.6–1.2 mg/dL and must be reported to the physician before the drug is given.

The physician may choose to delay the dose, provide additional IV hydration first, adjust the dose, or confirm that the expected benefit outweighs the renal risk. The nurse should not independently start the infusion when creatinine is elevated.

CautionPersistent hypercalcemia is the indication for the drug, not a reason to bypass the renal check. Mild hypokalemia of 3.4 mEq/L is not a contraindication to bisphosphonate therapy.

## 핵심 개념

- **Zoledronic acid** — A potent intravenous bisphosphonate used to treat hypercalcemia of malignancy and bone metastases; cleared by the kidneys and associated with dose-dependent nephrotoxicity.
- **Nephrotoxicity** — Kidney injury caused by a drug or toxin; for zoledronic acid, this is the most significant toxicity, requiring creatinine monitoring before each dose.
- **Hypercalcemia of malignancy** — Elevated serum calcium due to cancer-related bone resorption or humoral factors; IV bisphosphonates are a key treatment.
- **Serum creatinine** — A laboratory marker of kidney function; elevated levels indicate reduced glomerular filtration and increased risk for nephrotoxic drug accumulation.

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