# A kidney transplant client on tacrolimus reports a sudden rise in trough level. The nurse reviews recent changes. Which client behavior most likely caused the elevated level?

> source: MyMerci (mymerci.kr)  
> url: https://mymerci.kr/pages/nclex_q.php?qn_id=391872&lang=en  
> language: en  
> subject: Medical Emergencies  
> category: PA

## Question

A kidney transplant client on tacrolimus reports a sudden rise in trough level. The nurse reviews recent changes. Which client behavior most likely caused the elevated level?

## Option

1. Drinking 8 glasses of water
2. Eating leafy green vegetables
3. Walking 30 minutes daily
4. Starting grapefruit juice and clarithromycin — both inhibit CYP3A4, elevating tacrolimus levels and risking nephrotoxicity **✔ Correct answer**

**Correct answer: 4**

## Explanation

Correct (2): Tacrolimus is metabolized by CYP3A4; potent inhibitors (grapefruit juice, clarithromycin, azole antifungals, diltiazem) raise levels, causing tremor, AKI, hypertension, hyperglycemia, neurotoxicity. Avoid grapefruit; coordinate any new drug with the transplant team. Target trough varies (e.g., 5-15 ng/mL depending on time post-transplant). (1,3,4) Unrelated.

## In-depth explanation

Memory Tip Calcineurin inhibitor (tacrolimus·cyclosporine) = "CYP3A4 + Nephrotox + Neurotox + DM". Avoid grapefruit. St. John's wort INDUCES → rejection risk.

## Clinical scenario

Scenario 45-year-old male 6 months post-kidney transplant on tacrolimus; trough rose from 7 to 16 ng/mL with new tremor and creatinine rise. Diet review: started grapefruit juice and was prescribed clarithromycin.

## Key concepts

- **Calcineurin inhibitor** — Tacrolimus, cyclosporine; cornerstone post-transplant immunosuppression.
- **CYP3A4 interactions** — Tacrolimus level rises with inhibitors (grapefruit, azoles, macrolides, diltiazem); falls with inducers (rifampin, St. John's wort, phenytoin).
- **Tacrolimus toxicity** — Nephrotoxicity, tremor, hypertension, hyperglycemia, neurotoxicity, gum hypertrophy.

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