Proteins

This section is designed to help you understand the role of proteins and other nitrogen-containing compounds in health and disease. Topics covered will be biochemical theory, lab testing, result interpretation, and the disease-specific implications

Biochemical Theory and Physiology

• Protein Building Blocks: Made of amino acids, proteins perform diverse cellular functions
• Protein Synthesis: Transcription and translation guided by genetic code
• Protein Degradation: Breakdown of proteins into amino acids via lysosomes and proteasomes
• Amino Acid Metabolism: Transamination, deamination, and use in other compounds
• Nitrogen Balance: Intake vs. excretion, reflecting protein synthesis/breakdown
• Key Compounds
  • Proteins
  • Amino Acids
  • Urea
  • Uric Acid
  • Creatinine
  • Ammonia

Laboratory Test Procedures

• Protein Tests
  • Total Protein: Biuret method
  • Albumin: Dye-binding methods (BCG or BCP)
  • Prealbumin: Immunoassay
• Nitrogen Waste Product Tests
  • Urea (BUN): Enzymatic methods
  • Creatinine: Jaffe reaction or enzymatic assays
  • Uric Acid: Uricase method
  • Ammonia: Enzymatic or ISE methods
• Specialized Protein Tests
  • Protein Electrophoresis: Separates proteins by charge/size
  • Immunofixation Electrophoresis (IFE): Identifies monoclonal proteins
  • Tumor Markers: Measured by immunoassay
  • Cardiac Markers: Measured by immunoassay

Test Result Interpretation

• General Markers
  • High levels of proteins indicate high protein level
  • Low levels of protein indicate low protein level
• Kidney Function Tests
  • Elevated Urea and Creatinine indicate decreased kidney function
• Protein Electrophoresis: Interpret relative protein band intensity compared to others to find abnormal distributions, with special note of monoclonal gammopathy in the gamma globulin region
• Malignancy markers indicate increased cancer risk
• Patient specific medical history

Disease State Correlation

• Liver Disease: Decreased albumin, increased bilirubin and ammonia
• Kidney Disease: Elevated creatinine and urea, proteinuria
• Malnutrition: Decreased albumin and prealbumin
• Multiple Myeloma: Monoclonal protein on electrophoresis
• Heart Failure: Elevated BNP
• Cancer: Elevated tumor markers