Final answer:
Microinfarctions in the renal medulla due to sickle cell trait can decrease the ability to concentrate urine.
Step-by-step explanation:
Microinfarctions in the renal medulla due to sickle cell trait can eventually result in decreased ability to concentrate urine. This is because sickle cell trait causes red blood cells to assume a sickle shape, which can block blood vessels and impede blood flow. In the kidneys, this can lead to damage in the renal medulla, which is responsible for urine concentration. When the medulla is affected by microinfarctions, the kidneys may not be able to properly concentrate urine, resulting in decreased ability to conserve water.