Endo Paget Zoledronate Choice Dose

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name: endo-paget-zoledronate-choice-dose
description: Suggests a single 5‑mg intravenous dose of zoledronate as the treatment of choice in patients with active Paget’s disease who have no contraindication to IV zoledronate. Triggered when initiating pharmacologic therapy for Paget’s disease and confirming absence of renal impairment or other contraindications.
---

# Select zoledronate as first-line bisphosphonate

## STEP 1 — Gather Information
Confirm diagnosis of Paget’s disease (radiographs ± bone scan). Obtain baseline labs: serum total alkaline phosphatase (ALP) or specific bone formation/resorption marker (P1NP, BSAP, CTx, NTx), serum calcium, 25‑hydroxyvitamin D, creatinine/eGFR, and assess for pregnancy or hypersensitivity to zoledronate. Document disease extent and symptoms.

## STEP 2 — Rule In / Rule Out
Is there a contraindication to IV zoledronate (eGFR <35 mL/min, uncorrected vitamin D deficiency/hypocalcemia, pregnancy, known hypersensitivity)?  
- **Yes:** Rule out zoledronate; consider alternative bisphosphonate or non‑pharmacologic management.  
- **No:** Proceed to assess disease activity.

## STEP 3 — Classify or Stratify
Is there evidence of active bone turnover (elevated ALP or specific marker above the laboratory’s upper reference limit)?  
- **Yes:** Classify as active disease requiring treatment.  
- **No:** Consider monitoring only unless high‑risk features (e.g., impending surgery, neurologic symptoms) are present.

## STEP 4 — Decide
For active disease with no contraindication, administer a single 5‑mg intravenous zoledronate infusion over 15 minutes. Ensure pre‑infusion vitamin D repletion if deficient and monitor calcium and renal function post‑infusion.

## Clinical Guardrails / Mimics / Pitfalls
Do not give zoledronate if eGFR <35 mL/min or if vitamin D deficiency is uncorrected due to risk of symptomatic hypocalcemia. Avoid in pregnancy or lactation. Watch for acute phase reaction (fever, myalgias) – consider prophylactic acetaminophen/NSAID. Monitor for uveitis (rare) and inform patients to report eye pain, redness, or photophobia. Do not repeat dosing sooner than clinically indicated; retreatment is seldom needed within 5 years.

## Concrete Clinical Example
A 70‑year‑old woman with biopsy‑confirmed pelvic Paget’s disease, elevated ALP (140 U/L), normal creatinine (0.9 mg/dL), eGFR 78 mL/min, and sufficient vitamin D receives 5 mg zoledronate IV. At 3 months, ALP falls to 55 U/L (normal) and bone pain improves; remission persists at 2‑year follow‑up.

**Source:** Paget’s Disease of Bone: An Endocrine Society Clinical Practice Guideline, Endocrine Society, 2014, doi:10.1210/jc.2014-2910

> **TODO:** consider adding scripts/calc.py for the endo-paget-zoledronate-choice-dose calculator