Understanding Kidney Stone Density for Better Treatment

Kidney stone density is one of the most important—and most overlooked—factors in determining the best treatment for kidney stones. In this blog, I break down what kidney stone density actually means, how it’s measured through CT scans using Hounsfield units, and why this data can change everything about how you manage your stone. Understanding the density of your stone helps identify its type and decide whether natural therapies, shockwave treatment, or surgery is the right path forward.

Key Takeaways:

• Kidney stone density is measured using Hounsfield units (HU) from CT scans.

• Stones under 500 HU may dissolve with natural therapies.

• Stones over 850 HU are often too dense for shockwave lithotripsy.

• Knowing density helps avoid unnecessary or ineffective procedures.

 Let’s talk about something almost no one is discussing—kidney stone density.

This one metric can change everything about your treatment plan, yet it’s rarely talked about during urology appointments.

I want to walk you through exactly what it is, how it’s measured, and how it can completely shift the strategy for passing your stone—or avoiding unnecessary procedures.

What Is Kidney Stone Density?

Kidney stone density is how hard or soft your stone is, and it’s measured using a CT scan.

When you get a CT scan, it produces black and white images of your body. But behind the scenes, there’s a genius measurement happening. It’s called the Hounsfield Unit (HU) scale.

Developed decades ago, this scale assigns values to different tissue densities based on how much radiation they absorb during a scan.

• Water = 0 HU

• Air = –1000 HU

• Bone = Around 1000 HU

Everything else falls somewhere in between—including your kidney stone.

Why You Need a CT Scan First

If this is your first kidney stone, I always recommend asking your doctor for a CT scan, and make sure you request stone density information.

Here’s why that matters:

• Once you know the density of your stone, you can identify its type.

• Your stone type rarely changes over your lifetime unless you drastically change your diet or lifestyle.

• Future stones can be monitored with ultrasound or X-ray, which involve less radiation—because you’ll already know your density type.

This means you can avoid repeated CT scans, limit your radiation exposure, and make smarter decisions about treatment.

What Hounsfield Units Tell Us About Stone Type

Each stone type has a general Hounsfield Unit (HU) range. The higher the HU, the denser and harder the stone.

Here’s a breakdown of common stones and their average HU values:

• Brushite: Over 1000 HU (super dense)

• Calcium Oxalate Monohydrate: ~879 HU (very dense)

• Carbapatite: ~844 HU

• Calcium Oxalate Dihydrate: Below 500 HU

• Uric Acid & Struvite: Also typically below 500 HU

This info is gold. Why? Because different treatments work better (or worse) depending on the stone’s density. 

Stones Below 500 HU: Dissolution Is Possible

If your stone is below 500 HU, you’re in luck. These stones may be susceptible to dissolution.

That means, under the right conditions, they can break apart and pass as gravel or sand.

This is where natural treatments like Cleanse, which contains anti-lithic herbs, can make a big difference. You’re not just trying to push out a whole stone—you’re helping your body dissolve and break it down before it ever gets to that point.

If I had a stone with <500 HU, I’d be doing everything I could to target that window of opportunity.

Stones Over 850 HU: Shockwave May Not Work

One of the most common kidney stone treatments is shockwave lithotripsy (or ESWL).

It’s popular because it’s non-invasive. They hit the stone with sound waves to try to break it apart so you can pass it more easily.

But there’s a problem.

Shockwaves don’t work well on dense stones. And if your stone has a HU value over 850, it might be too hard for the treatment to work effectively.

Some urologists cut off shockwave therapy at 850 HU, while others go up to 1000 HU—but most agree, the higher the density, the lower the chance it will work.

This rules out shockwave for:

• Brushite stones

• Calcium Oxalate Monohydrate stones

• Often Carbapatite stones

Trying to break these with sound waves? Not likely to succeed.

What If You Can’t Use Shockwave?

If your stone is too dense, the next option is often ureteroscopy.

This involves inserting a small scope up your urinary tract to break apart or retrieve the stone using a laser or a basket.

This method doesn’t rely on stone density. It works whether the stone is soft or hard.

It’s more invasive than shockwave, but still avoids open surgery.

The Role of Density in Surgery (PCNL)

The most invasive option is Percutaneous Nephrolithotomy (PCNL).

This involves cutting into your side to directly access and remove the stone from your kidney. It’s usually used for struvite or staghorn stones that are too large to pass.

Here’s the twist: If your stone has a HU under 675, it might actually be too soft to extract successfully using this method.

Stones in this range may break apart during removal, causing fragments to remain behind—or worse, more pain later.

So if your doctor is suggesting PCNL for a lower-density stone, it’s time to hit pause and get a second opinion.

Quick Recap: What Your HU Value Tells You

Let’s summarize what you can do based on your kidney stone density:

• HU < 500:

  • Great candidate for natural or medical expulsive therapy

  • Target dissolution using anti-lithics

• HU > 850:

  • Shockwave lithotripsy likely won’t work

  • Consider ureteroscopy instead

• HU < 675:

  • May not be suitable for PCNL due to risk of fragmentation

Why You Must Take Charge

I can’t emphasize this enough: Your urologist should know this information, but many people we talk to never even hear the word "density" mentioned.

That’s why it’s critical to ask for your HU value during your CT scan.

It will help you avoid unnecessary procedures and get the treatment that actually works best for your specific stone type.

And don’t forget—this info is valid not just now, but for every future stone you deal with.

Take This Info With You

To help you out, I’ve created a free PDF guide you can bring to your doctor’s appointment. It shows you how to interpret HU values and match them to the right treatment options.

If you’re watching this on our website, join my community to get access to the PDF.

Final Thoughts

Kidney stone density might not be the first thing your doctor talks about—but it’s one of the most important details for determining your treatment path.

Knowing your Hounsfield Unit value gives you power:

• Power to choose a treatment that works

• Power to avoid unnecessary procedures

• Power to pass your stone faster, safer, and with less pain

Take charge of your health. Ask the right questions. And use this knowledge to get the outcome you deserve.