Clinical Biochemistry I (MTML 311)

Clinical Biochemistry I (MTML 311)

• Course: Clinical Biochemistry I
• Course Code: MTML 311
• Semester: 5th
• Lecturer: Dr.rer.med/ Saleh Bilgasem
• Year: 2024

Clinical Biochemistry

• Clinical biochemistry is a division of medical biochemistry
• It deals with physiological and unnatural chemical measurements in bodily fluids (blood, urine, etc.)
• Includes qualitative and quantitative analyses

Purpose of Clinical Chemistry Tests

• Applied biochemistry to diagnose conditions
• Measures various chemical constituents in bodily fluids
• Qualitative and quantitative analyses are performed on blood, urine, and other bodily fluids.
• Determination of urea, creatinine, and other inorganic substances (Na, K, Ca, Cl) can help diagnose diseases.
• Methods can be manual, kit-based, or automated.

Types of Specimens for Chemical Analysis

• Whole blood, serum, or plasma are common specimens
• Serum is the most common, collected in tubes without anticoagulants to allow clotting.
• Urine: often collected over 24 hours
• Other specimens: Pleural fluid, cerebrospinal fluid (CSF)

Obtaining Blood Samples

• Capillary blood: from a finger or thumb (used for hematological analysis - RBC, WBC counts, Hb etc)
• Arterial blood: for blood gas analysis (CO2, O2, HCO3, pH etc). Restricted
• Venous blood: for analysis of various chemical constituents (glucose, urea, cholesterol, etc.)

Avoiding Hemolysis

• Clean and dry syringe and needle
• Apply minimum constriction to the arm
• Allow slow and steady blood flow into the syringe
• Remove needle before expelling blood into the tube
• Gentle rotation when anticoagulant is present

Anticoagulants

• Heparin: Convenient, does not alter blood constituents, acts as antithrombin preventing thrombin and fibrin formation
• Sodium and potassium oxalate: Form insoluble complex with calcium preventing coagulation
• Ammonium oxalate: (3 parts ammonium oxalate + 2 parts potassium oxalate) used for hematological investigations
• Sodium citrate: Does not precipitate calcium but ionizes it. Used in 3 mg/ml blood.
• Sodium fluoride: Preservative for glucose measurements. Acts as a weak anticoagulant. Inhibits glycolysis enzymes (e.g., Enolase) (2mg/ml blood)
• Ethylene diamine tetraacetic acid (EDTA) preserves cellular components in blood samples. Chelates calcium needed for clotting (2mg/ml blood)

Protein Precipitants

• Used in clinical chemistry analysis to remove proteins from serum for preparation of protein-free filtrate (PFF)
• Common precipitants include:
  • Trichloroacetic acid
  • Alkaline zinc salt
  • Organic solvent

Urine

• Urine is an ultrafiltrate of blood, filtered and excreted by the kidneys
• Terms to describe urine volume:
  • Polyuria: increased daily urine output
  • Oliguria: decreased daily urine output
  • Anuria: complete suppression of urine output

Changing Urine Constituents

• Bacterial growth can convert urea to ammonia, altering pH
• Yeast can affect glucose content, making samples unsuitable for glucose determination
• Phosphate and uric acid may precipitate in alkaline or cold urine, respectively

Urine Sample Processing

• Chemical examination (sugar, protein, acetone, bilirubin, etc.)
• Macroscopic examination (color, odor, specific gravity, transparency)
• Microscopic examination (casts, pus, RBCs, crystals, etc.)

Urine Samples

• Different types of urine samples: Random, Timed, Catheterized, Bacteriological considerations
• Normal constituents: Urea, ammonia, creatinine, uric acid, amino acids, salts, and minerals

Abnormal Urine Constituents

• Albuminuria: presence of albumin in urine, often due to stress, exercise, or underlying conditions
• Glycosuria: presence of glucose in urine, indicative of diabetes mellitus
• Ketonuria: presence of ketone bodies in urine, often during periods of low carbohydrate intake or increased fat metabolism.
• Bilirubinuria: presence of bilirubin in urine, often indicative of liver or gallbladder problems
• Hematuria: presence of RBCs in urine, which can be from a variety of conditions

Electrolytes

• Electrolytes are distributed in body fluids
• Cations: Na, K, Ca, Mg
• Anions: Cl, HCO3, H2PO4, HPO4, SO4, protein
• Major cation in extracellular and intracellular fluids are different

Sodium (Na+)

• Important for acid-base balance, blood osmotic pressure, cell permeability
• Clinical significance: Normal serum sodium levels (135-148 mmole/L).
• Hyponatremia: Decreased levels
• Hypernatremia: Increased levels

Potassium (K+)

• Major intracellular ion, important for muscle function, nerve impulse transmission, osmotic pressure, and enzyme activation.
• Clinical significance: Normal serum potassium levels (3.5-5 mmole/L).
• Hyperkalemia: Increased levels
• Hypokalemia; Decreased levels

Phosphorus

• Important for bone mineralization, energy transfer (ATP), etc.
• Clinical significance: Normal serum phosphorus levels (2.4-4.5 mg/dL).
• Hyperphosphatemia: Increased levels
• Hypophosphatemia: Decreased levels

Iron (Fe)

• Part of hemoglobin and myoglobin. Important in oxygen transport and regulation of cell growth and differentiation
• Clinical significance: increased or decreased iron levels are related to corresponding conditions like hemolytic anemia

This quiz covers the fundamentals of Clinical Biochemistry I, focusing on physiological and chemical measurements in bodily fluids. Students will explore the purpose of clinical chemistry tests and the types of specimens used in analysis. Prepare to test your knowledge on biochemical analysis techniques and their applications in diagnosing diseases.