CPT® Code 78111

The CPT® Code 78111 refers to a laboratory test that measures plasma volume (PV) using a radiopharmaceutical volume-dilution technique, specifically when multiple samplings are performed. This procedure is essential in evaluating various medical conditions related to blood volume, such as hypovolemia, which is a decreased blood volume, and hypervolemia, which indicates an increased blood volume. It is also utilized in cases of acute blood loss and shock, where understanding the plasma volume can guide treatment decisions. The test employs radiolabeled protein tracers, primarily I-125 radioiodinated serum albumin (I-125 RISA), although Technetium-99m (99mTc) human serum albumin (HSA) may also be utilized. The process begins with the collection of the patient's height and weight to ensure accurate calculations. Following this, venous access is established, and a baseline blood sample is collected. The radiolabeled pharmaceutical is then injected, allowing it to circulate throughout the body. Subsequent venipunctures are performed to draw blood samples, which can be done either as a single sample or multiple samples at predetermined intervals. Each sample undergoes a microhematocrit measurement, and the remaining blood is centrifuged to separate the plasma from red blood cells. The data obtained from the patient's samples are analyzed using specific formulas that compare the dilution factors of the radiolabeled tracer with standardized samples, taking into account the patient's individual height, weight, and hematocrit levels. This comprehensive approach ensures accurate assessment of plasma volume, which is critical for effective patient management.