Biochem flashcards

🔴 1. Iron Metabolism & Anaemia

📌 Key Lab Values:

• Ferritin: First to fall in deficiency.

  • Normal: 15–200 µg/L

  • <15 = depleted stores

  • Increased in inflammation (not always reliable alone)

• MCV:

  • Low (<80 fL) = microcytic (e.g., iron deficiency)

  • Normal (80–100) = normocytic

• Hb (F): <120 g/L = anaemia

• Transferrin Saturation: Low in iron deficiency (<20%)

⚠ Risk Factors:

• Menstruation

• Vegetarian/vegan diet

• Tea/coffee with meals (tannins inhibit iron)

• Low vitamin C intake

• Malabsorption (e.g., coeliac, IBD)

🛠 Management:

• Iron-rich foods: red meat, tofu, lentils, spinach

• Vitamin C with meals (enhances non-haem iron absorption)

• Avoid tea/coffee with iron-rich meals

• Supplement if ferritin very low

☀ 2. Vitamin D, Calcium & PTH

📌 Lab Ranges:

• 25(OH)D (nmol/L):

  • 50 = sufficient

  • 30–50 = insufficient

  • <30 = deficient

• Calcium: 2.2–2.6 mmol/L

• PTH: Raised in vitamin D deficiency (secondary hyperparathyroidism)

🧓 At-Risk Groups:

• Older adults (↓ skin conversion & dietary intake)

• Housebound or always indoors

• Low dairy/fat intake

• Darker skin tones (require more sunlight)

🛠 Public Health Guidance:

• 10 µg/day (400 IU) vitamin D supplement year-round (UK/SACN)

• Encourage fortified foods (e.g., plant milks, cereals)

• Safe sunlight exposure (10–20 mins/day)

💊 3. Vitamin B12 & Folate

📌 Key Facts:

• B12 absorption:

  • Requires intrinsic factor

  • Absorbed in the ileum

• Deficiency Symptoms:

  • Macrocytic anaemia (MCV >100 fL)

  • Neurological signs (tingling, ataxia)

  • Glossitis

• At-risk groups:

  • Vegans

  • Elderly (↓ gastric acid)

  • Metformin or PPI users

• Folate (B9):

  • Needed for DNA synthesis

  • Deficiency → macrocytic anaemia, neural tube defects

⚠ Folate can mask B12 deficiency in blood tests but not neurologically.

🧬 4. Gut Hormones (GLP-1, Ghrelin, PYY)

🧪 GLP-1:

• Post-meal secretion (incretin hormone)

• Functions:

  • Enhances insulin secretion

  • Delays gastric emptying

  • Suppresses appetite

• Therapeutic use:

  • GLP-1 receptor agonists (e.g., semaglutide)

  • Used in obesity and T2DM

🧪 Ghrelin:

• Secreted pre-meal

• Stimulates hunger

🧪 PYY:

• Released post-meal

• Promotes satiety

🧃 5. Nutrient Absorption & Inhibitors

🔒 Inhibitors:

• Phytates (grains, legumes) → block iron, zinc

• Tannins/polyphenols (tea, coffee) → reduce iron absorption

• Calcium → competes with iron, magnesium, zinc

🍷 Alcohol:

• Interferes with:

  • Thiamine (B1) absorption → risk of Wernicke-Korsakoff

  • Folate

• Chronic use → poor appetite, malabsorption

🧪 6. Nutrient Status Assessment

🏥 7. Public Health Nutrition

🧴 Vitamin D:

• UK guidance: 10 µg/day supplement for everyone

• Higher needs in:

  • Ethnic minorities

  • Pregnant women

  • Infants

🌾 Folate:

• Government policy to fortify flour (UK/ROI)

• Goal: reduce neural tube defects

• Especially important in early pregnancy