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Foundation Sciences · Biochemistry

Calcium and Phosphate Biochemistry

⏱️ 45–60 minutes read 📖 Biochemistry

PTH, vitamin D and FGF-23 regulation of calcium and phosphate; bone, gut and renal handling.

📌 Learning Objectives

  • Describe the key principles of calcium and phosphate biochemistry.
  • Explain the clinical relevance of calcium and phosphate biochemistry.
  • Recognise common conditions linked to calcium and phosphate biochemistry in MLA-style scenarios.

📋 Overview

PTH, vitamin D and FGF-23 regulation of calcium and phosphate; bone, gut and renal handling. This topic integrates with pathology, pharmacology and clinical medicine and is frequently tested in UK medical school exams and the MLA.

🔬 Basic Science

PTH, vitamin D and FGF-23 regulation of calcium and phosphate; bone, gut and renal handling. Detailed mechanisms, regulation and molecular interactions underpin both normal physiology and disease.

🏥 Clinical Relevance

Hypocalcaemia (Chvostek/Trousseau), hyperparathyroidism, osteomalacia, CKD-MBD.

🧪 Investigations

Relevant laboratory tests, imaging or histological examination are used as appropriate to the clinical context.

💊 Management

Management is condition-specific; principles include addressing the underlying biochemical/structural derangement, supportive care and targeted therapy where available.

Revision Resources – expand the sections below for high-yield notes, exam pearls, key facts and further reading.

🎯 MLA High-Yield Notes & Quick Revision ⌄
High-yield topic for the UK MLA — frequently appears in SBA questions linking biochemistry concepts to clinical presentations and management decisions.
Applying biomedical science to clinical practice Diagnosis and investigation Pathophysiology of common conditions
  • PTH, vitamin D and FGF-23 regulation of calcium and phosphate
  • bone, gut and renal handling.
⭐ Exam Pearls ⌄
⭐ High Yield
PTH ↑ Ca, ↓ PO4 (renal)
Calcitriol ↑ both Ca and PO4 absorption
FGF-23 ↓ PO4 reabsorption
Ionised calcium is biologically active
💡 Clinical Pearl
: Hypocalcaemia (Chvostek/Trousseau), hyperparathyroidism, osteomalacia, CKD-MBD.
⚠️ Exam Tip — Common Mistakes
Confusing calcium and phosphate biochemistry with related but distinct mechanisms.
Memorising pathways without linking to clinical disease.
🔑 Key Facts ⌄
PTH ↑ Ca, ↓ PO4 (renal)
Calcitriol ↑ both Ca and PO4 absorption
FGF-23 ↓ PO4 reabsorption
Ionised calcium is biologically active
📚 References ⌄
  1. BMJ Best Practice
  2. Robbins Basic Pathology
  3. Lippincott Illustrated Reviews: Biochemistry
  4. Wheater's Functional Histology
  5. NICE guidance where applicable.

Further Resources

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