Why Routine Renal Ultrasounds Are Standard Protocol During Active ERT

Why Routine Renal Ultrasounds Are Standard Protocol During Active ERT

Enzyme replacement therapy (ERT) with Strensiq® (asfotase alfa) has transformed care for people with hypophosphatasia (HPP), improving bone mineralization and quality of life. Alongside its benefits, active ERT can alter mineral balances in the body, potentially leading to kidney calcification. For this reason, kidney calcification monitoring via routine renal ultrasound has become standard protocol. Below, we explain why these scans are important, how often they’re recommended, and what you can expect.

Understanding the Link Between Strensiq and Kidney Health

Strensiq works by replacing deficient tissue-nonspecific alkaline phosphatase (TNSALP), a key enzyme for bone mineralization. As bone healing accelerates, calcium and phosphate levels in blood and urine can shift:

• Increased calcium availability: Rapid bone mineralization may transiently raise blood calcium (hypercalcemia).
• Altered phosphate clearance: Phosphate released or retained during bone turnover can accumulate in the kidneys.
• Risk of nephrocalcinosis: Deposits of calcium-phosphate complexes can form in renal tissue, even without symptoms.

Without regular monitoring, these deposits can progress silently, compromising kidney function over time.

Why Renal Ultrasound Is the Preferred Monitoring Tool

Renal ultrasound is a noninvasive, painless imaging test that uses sound waves to visualize kidney structure. It is ideal for kidney calcification monitoring because:

• No radiation exposure—safe for repeated use, even in infants and children.
• High sensitivity for detecting calcifications, cysts, or early scarring.
• Widely available in hospitals and imaging centers.
• Quick procedure, typically completed in 15–30 minutes.

Recommended Ultrasound Schedule During Active ERT

International guidelines and the Strensiq prescribing information recommend regular renal ultrasounds to catch kidney calcifications before they cause serious damage. A typical schedule may include:

• Baseline ultrasound prior to starting Strensiq.
• Follow-up at 6 months after ERT initiation.
• Annual scans thereafter, or more frequently if calcifications are detected.
• Additional scans after any episode of hypercalcemia or unexplained changes in kidney markers.

Your healthcare team will tailor this schedule based on age, kidney function tests, and any prior imaging findings.

What Healthcare Providers Look For

During a renal ultrasound, radiologists evaluate:

• Presence, size, and location of echogenic (bright) areas suggestive of calcium deposits.
• Kidney size and corticomedullary differentiation.
• Any signs of obstruction, cysts, or other structural abnormalities.
• Changes over time in calcification burden.

This information helps nephrologists and metabolic specialists decide if ERT dosage adjustments or additional interventions (e.g., hydration, dietary modifications) are needed.

Benefits of Early Detection

Catching kidney calcifications early offers several advantages:

• Prevents progression: Small deposits can often be managed without invasive procedures.
• Maintains kidney function: Interventions to normalize mineral levels reduce the risk of long-term scarring.
• Helps fine-tune therapy: Adjusting Strensiq dose or supplementing with vitamin D/calcium guidance can optimize bone benefits while protecting kidneys.
• Provides peace of mind: Regular imaging reassures families that potential side effects are being watched closely.

Integrating Ultrasound Findings Into Your Care Plan

If your ultrasound shows any calcifications, your care team may:

• Check blood calcium, phosphate, and parathyroid hormone levels.
• Recommend dietary changes (e.g., moderate calcium intake, adequate hydration).
• Consider temporary ERT dose modification under close supervision.
• Increase ultrasound frequency (e.g., every 3–6 months) until stabilization.
• In rare cases, consult a nephrologist or urologist for further evaluation.

Patient-Friendly Tips for Preparing and Coping

Waiting for any medical test can be stressful. Here are a few pointers to make renal ultrasound smoother:

• Wear loose clothing—gowns are usually provided.
• Drink water as instructed so your bladder is lightly filled (improves image quality).
• Bring a playlist or book to help you relax in the waiting area.
• Ask your sonographer to explain what you’re seeing on screen.
• Plan a light snack or activity afterward as a small reward.

Monitoring Beyond Ultrasound

While renal ultrasound is key for kidney calcification monitoring, comprehensive care also includes:

• Routine blood tests for calcium and phosphate.
• Urinalysis to detect crystalluria or proteinuria.
• Regular bone density scans to assess ERT efficacy.
• Clinical evaluations of growth (in children), pain, and mobility.

When to Seek Immediate Medical Advice

Most mineral shifts on Strensiq are mild and reversible with early intervention. However, certain symptoms warrant prompt attention:

• Severe flank pain, fever, or burning on urination.
• Sudden changes in urine output or color.
• Unexplained fatigue, nausea, or muscle weakness (signs of high calcium).
• Any signs suggestive of kidney stones or acute obstruction.

Speak to a doctor immediately if you experience these or any other life-threatening or serious symptoms.

Taking Charge of Your Symptoms

It’s natural to have questions about new aches, pains, or changes during ERT. If you’re unsure whether something requires medical follow-up, consider a free, online symptom check, using the doctor approved Ubie Symptom Checker. This tool can help you decide if you need to contact your healthcare team right away.

Key Takeaways

• Strensiq improves bone health in HPP but can alter mineral balance, increasing the risk of nephrocalcinosis.
• Routine renal ultrasounds are noninvasive, safe, and effective for kidney calcification monitoring.
• Ultrasounds at baseline, 6 months, and annually (or more often if needed) detect calcifications early.
• Early detection allows for diet, hydration, or ERT dose adjustments to protect kidney function.
• Combine ultrasounds with blood tests and clinical assessments for comprehensive monitoring.
• Always speak to a doctor about any serious or life-threatening concerns.

By staying proactive with routine renal ultrasound exams and open communication, you and your healthcare team can maximize the benefits of Strensiq while minimizing risks to your kidneys.