Copper, Plasma and RBC is a comprehensive test that measures copper levels in both plasma and red blood cells to evaluate copper status and diagnose deficiency or toxicity. Copper is an essential trace element required for the function of numerous enzymes involved in energy production, iron metabolism, connective tissue formation, and antioxidant defense. The test provides two complementary measurements: plasma copper reflects recent copper intake and transport, while RBC copper indicates long-term copper status and tissue stores. Copper deficiency can cause anemia, neutropenia, bone abnormalities, and neurological problems. Elevated copper levels may indicate Wilson's disease, copper toxicity, or inflammatory conditions. This test is particularly valuable for evaluating unexplained anemia, monitoring patients on long-term parenteral nutrition, and diagnosing rare genetic disorders of copper metabolism.