Diagnostic reagents are substances used in laboratory tests to detect or measure specific biological markers in samples, such as blood or urine. These reagents can include chemicals, antibodies, or enzymes that react with the target substance, producing a measurable change, such as a color change or fluorescence. They are essential tools in medical diagnostics, helping healthcare professionals identify diseases or monitor health conditions. These reagents are often part of diagnostic kits, which may also include equipment and instructions for use. Common applications of diagnostic reagents include testing for infections, monitoring diabetes, and screening for genetic disorders. Their accuracy and reliability are crucial for effective patient care.