Diagnostic Aids & Agents Overview

Diagnostic Aids & Agents

• Diagnostic aids are substances used to identify impairment of bodily functions. They are not typically used for other medicinal purposes.
• The effectiveness of diagnostic agents is characterized by several factors:
  • Solubility
  • Excretion rate
  • Metabolism
  • Chemical configuration and composition
• Diagnostic agents are generally categorized into two classes:
  • Clinical diagnostic chemicals: Determine normal and abnormal products in urine, blood, feces, and other bodily fluids.
  • Diagnostic agents: Administered directly into or within the body. These agents are further categorized into three groups:
    • Radiopaque substances: Cast shadows on X-ray images, useful for fluoroscopy. Examples include barium sulfate (BaSO4) and radiopaque iodine-containing compounds.
    • Components for testing functional capacity: Assess functional capabilities within the body.
    • Compounds modifying physiologic action: Alter physiological processes for assessment.

Classification of Diagnostic Agents

• Diagnostic agents are classified according to their intended function:
  • Gall bladder function (e.g., cholecystography, cholangiography using locetamic acid, lodipamide, and tyropanoate sodium)
  • Gastric function (e.g., pentagastrin, Congo red)
  • Liver function (e.g., indocyanine green)
  • Ophthalmic diagnostics (e.g., fluorescein sodium)
  • Pancreatic function (e.g., bentiromide)
  • Intestinal function (e.g., barium sulfate, xylose)
  • Kidney function (e.g., aminohippurate sodium, indigotin disulfonate, phenolsulphophthalein)
  • Others like lymphatic system, bronchial airway hyperacidity, drug hypersensitivity, X-ray contrast mediums (diatriazoic acid, locetamic acid, lothalamic acid, propyliodone), and miscellaneous (erythrosin sodium, Evans blue)

Radiocontrast Agents

• Radiocontrast agents such as iodine-based compounds and barium sulfate enhance the visibility of internal structures during X-ray procedures, computed tomography, and fluoroscopy.
• Barium sulfate is a water-insoluble white powder given orally or directly into the gastrointestinal tract to enhance X-ray visibility of the gastrointestinal tract. It's used to diagnose GI tract issues.

Gall Bladder Function: Tyropanoate Sodium

• Tyropanoate sodium is an oral radiopaque agent used in cholecystography to evaluate gallstones and cystic duct obstruction.
• It is a derivative of iodine.

Locetamic acid

• Locetamic acid is an oral cholecystographic agent useful in visualizing the gallbladder using X-rays.

Gastric Function: Congo Red

• Congo red is used to evaluate acid production in the stomach by assessing the colour change in response to stimulation and neutralization.
• Its use involves spraying a Congo red solution onto the gastric or duodenal mucosa, following stimulation by pentagastrin.

Liver Function: Indocyanine Green

• Indocyanine green is a fluorescent dye used in assessing hepatic function, cardiac output, liver blood flow, and regional blood flow in various organs like kidneys, eyes, and lungs.
• It's injected intravenously, and its clearance from the body (half-life ~3-4 minutes) is used to assess liver function.

Ophthalmic Diagnostic Aids: Fluorescein Sodium

• Fluorescein sodium is an orange dye used in ophthalmic exams to detect corneal lesions and foreign bodies in the eye.
• Blue light is used to visualize the fluorescein dye.

Pancreatic Function: Bentiromide

• Bentiromide is a diagnostic agent used to evaluate pancreatic function. Its chemical structure is presented.

Explore the role of diagnostic aids and agents in identifying bodily function impairments. This quiz covers their categorization, effectiveness factors, and specific types including clinical chemicals and radiopaque substances. Test your knowledge on these essential substances used in medical diagnostics.