Vitamins, Nutrition

This section covers vitamins and nutrition in special chemistry - biochemical theory, lab procedures, result interpretation, and disease correlations

Biochemical Theory and Pathways

Vitamins as Essential Nutrients
- Organic compounds needed in small amounts for metabolic processes; the body cannot synthesize them adequately
- Classified as water-soluble (B vitamins, C) and fat-soluble (A, D, E, K)
General Functions
- Act as coenzymes (assist enzymes), antioxidants (protect against damage), or regulators (influence gene expression)
Specific Roles
- B vitamins: Involved in energy metabolism
- Vitamin C: Antioxidant, collagen synthesis
- Vitamin A: Vision, cell differentiation
- Vitamin D: Calcium and phosphate regulation
- Vitamin E: Antioxidant
- Vitamin K: Blood clotting
Metabolic Pathways
- Absorption: Occurs in the small intestine
- Transport: Via bloodstream, either freely or bound to proteins
- Storage: Fat-soluble vitamins stored in the liver/adipose tissue
- Excretion: Water-soluble vitamins excreted in urine

Analytical Principles
- Spectrophotometry: Measures light absorbance
- Fluorometry: Measures fluorescence
- Immunoassays: Uses antibody-antigen interactions (e.g., ELISA)
- Chromatography: Separates compounds (e.g., HPLC, GC)
- Mass Spectrometry: Measures mass-to-charge ratio (LC-MS)
- Atomic Absorption Spectrometry: Measures light absorption by free atoms
Pre-analytical Considerations
- Patient Preparation: Fasting, medication/supplement restrictions
- Specimen Collection: Proper tubes, order of draw, technique
- Specimen Processing: Timely centrifugation, separation, storage
Quality Control
- Run QC samples to ensure accuracy and precision
- Calibrate instruments regularly

Reference Intervals
- Use appropriate reference ranges based on age, sex, population
Clinical Context
- Interpret results with patient history, symptoms, and other lab data
Interpreting Vitamin Levels
- Evaluate whether the vitamin is high, low, or within range
- Consider test limitations: Assay specificity, interfering substances
Influencing Factors
- Medications, diet, malabsorption, lifestyle

Deficiency Disorders
- Vitamin B1 (Thiamin): Beriberi, Wernicke-Korsakoff Syndrome
- Vitamin B2 (Riboflavin): Ariboflavinosis
- Vitamin B3 (Niacin): Pellagra
- Vitamin B6 (Pyridoxine): Neurological symptoms, dermatitis
- Vitamin B9 (Folate): Megaloblastic anemia, neural tube defects
- Vitamin B12 (Cobalamin): Megaloblastic anemia, neurological problems
- Vitamin C (Ascorbic Acid): Scurvy
- Vitamin A: Night blindness, xerophthalmia, immune dysfunction
- Vitamin D: Rickets/osteomalacia
- Vitamin E: Neurological symptoms, hemolytic anemia
- Vitamin K: Bleeding disorders
Toxicities
- Vitamin A: Liver damage, birth defects
- Vitamin D: Hypercalcemia, kidney stones
- Vitamin E: Increased bleeding risk
- Niacin: Flushing, liver damage
Other Disease Correlations
- Chronic diseases: CV disease, cancer, diabetes
- Malabsorption syndromes: Affect vitamin/mineral absorption
Key Biochemical Tests
- Vitamin levels (serum or plasma)
- Red blood cell folate
- Homocysteine and methylmalonic acid (B12 status)
- 25-hydroxyvitamin D (Vitamin D status)
- Prothrombin time (Vitamin K status)