Which type of uric acid crystal is characterized by spicules?

The type of uric acid crystal characterized by spicules is acid urate. These crystals often appear in a needle-like or spiculated form and are typically found in urine with a low pH, which can occur in conditions such as gout or when there is rapid turnover of cells. The spicules can be observed under polarized light microscopy, making them distinct from other types of crystals.

In contrast, sodium urate crystals, although related to uric acid, do not have the characteristic spiculated appearance and are less common in urine. Calcium oxalate crystals can appear in different shapes, but they are more commonly recognized in their distinctive envelope or dumbbell shapes and do not exhibit spicules. Amorphous phosphates, on the other hand, do not form well-defined crystals and are instead observed as a granular precipitate, lacking any spicules at all. The unique spiculate appearance of acid urate crystals sets them apart in the analysis of urine sediments, confirming their identity as the correct answer.