A cadmium test measures the concentration of the toxic heavy metal cadmium in blood, urine, or hair samples. Cadmium exposure typically occurs through industrial workplaces, tobacco smoke, contaminated food, or batteries, and the metal can accumulate in organs such as the kidneys and liver over time. This diagnostic test is primarily used to assess acute or chronic heavy metal toxicity, monitor occupational safety compliance, and investigate unexplained renal dysfunction or bone mineral loss. Because cadmium has a long biological half-life, clinical evaluation helps guide removal from exposure sources and directs supportive medical management.