Which of the following statements regarding urine casts is TRUE?
A. Large numbers of casts in urine usually indicate active renal disease. B. Casts will dissolve in alkaline urine. C. Casts contain material in their matrix that was present in the renal tubule when the cast was formed. D. All of the above.
All of the above.-d: casts are formed by the slow movement of material in the renal tubules and are molded by the tubular lumen. casts are comprised predominantly of a protein matrix that also contains substances that were present in the tubule when the cast was formed, such as hyaline, white or red blood cells, or epithelial cells. when present in large numbers, they indicate active renal disease. few casts, however, may not be significant, especially if not found on repeat sediment exams.
casts readily dissolve in alkaline urine, so it is imperative that urine samples be evaluated immediately before the urine chemistry changes.