Which stones are typically radiolucent?

Uric acid stones are typically radiolucent, meaning they do not appear on standard X-rays and can be challenging to detect using this imaging modality. This characteristic arises because uric acid has a lower density compared to other types of stones, such as calcium or struvite stones, which contain elements that are often visible on X-ray imaging due to their greater density and mineral content.

In the context of urinary stones, calcium stones are the most common and are typically radiopaque, meaning they can be easily seen on X-rays. This includes calcium oxalate and calcium phosphate stones. Struvite stones, formed in response to urinary tract infections, are also radiopaque because they contain magnesium and ammonia, which contribute to their visibility. Cystine stones, while less commonly encountered, are also generally radiopaque.

Uric acid stones are unique among these options because they can form in acidic urine and are not as mineral-rich, allowing them to escape detection through conventional radiographic techniques. Instead, these stones might be better visualized using ultrasound or CT scans. Understanding the radiographic properties of different types of stones is critical in guiding the appropriate diagnostic and therapeutic strategies for patients with urolithiasis.