In healthy people, new red blood cell creation is roughly equal to red cell recycling/destruction. When a large number of red blood cells are suddenly fragmented, which of the following substances may be found in the plasma in excess concentration?

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Quizplus · Accepted Answer

Bilirubin is a metabolic by-product of hemoglobin destruction. Bilirubin is conjugated by hepatocytes, but during times of relatively high release of hemoglobin into the circulation, more bilirubin is released than can be conjugated, and unconjugated bilirubin circulates in the plasma. (Conjugated bilirubin is water soluble and is excreted in the urine. Unconjugated bilirubin is not water soluble. It may accumulate in body tissues, such as the skin, and cause jaundice.) The D-dimer is a by-product of the degradation of a blood clot. Fibrin is the mesh-like protein formed from fibrinogen. It is one component of a blood clot. Tissue plasminogen activator is an enzyme that breaks up fibrin. Although it is naturally manufactured within the bloodstream, it can also be administered as a fibrinolytic drug as a "clot busting" medication.

In Healthy People, New Red Blood Cell Creation Is Roughly