Clinical biochemistry (clinical chemistry) measures chemicals in blood and other fluids—things like glucose, urea, liver enzymes, lipids and electrolytes—to help doctors understand a patient’s health. Spectrophotometry in simple words Most chemistry tests are spectrophotometric. The idea is straightforward: Reagent + Sample → Color/Light change. When the patient sample reacts with a reagent, the mixture changes how it absorbs  light at a specific wavelength. Shine light → Mea