Related Subjects:
|Ferritin
|CEA
|ESR
|CRP
|ALP
|LDH
|HbA1c
|Alpha Fetoprotein
|Anti-Hu ab
|Biochemical Lab values
🧪 Lactate Dehydrogenase (LDH) is an enzyme present in many tissues.
High levels signal tissue breakdown and can be raised in infections, haemolysis, cancers, liver and kidney disease, muscle injury, and myocardial infarction (MI).
📖 About LDH
- 🔬 Isoforms: 5 types (LD1–LD5), each linked to specific tissues:
- ❤️ LD1: Heart & red blood cells
- 🩸 LD2: Heart & red blood cells (normally predominant)
- 🌬️ LD3: Lungs & other tissues
- 🫁 LD4: Kidneys & pancreas
- 💪 LD5: Liver & skeletal muscle
- ⚡ Function: Converts pyruvate ↔ lactate in anaerobic glycolysis → key for energy in hypoxia.
- 📉 Prognosis in Cancer: Raised LDH = poor prognostic marker (reflects high cell turnover & tumour burden).
- ❤️ MI indicator (historical): LDH1 > LDH2 “flip” once used for diagnosis; troponins now preferred.
📈 Conditions with Elevated LDH
- ❤️ Myocardial Infarction (MI): Rises in 24–48h, peaks 48–72h, persists 7–10 days.
- 🦠 Pneumocystis Pneumonia (PCP): Often elevated in immunocompromised patients.
- 🩸 Haemolysis: (e.g., autoimmune haemolytic anaemia, sickle cell) → RBC breakdown raises LDH.
- 🧠 Stroke: Raised with both ischemic and haemorrhagic injury.
- 🎗️ Malignancy: Aggressive tumours (lymphoma, testicular cancer). Used for prognosis & monitoring response.
- 🤒 Infectious Mononucleosis: May show systemic rise in LDH.
- 🔥 Pancreatitis: Cell damage raises LDH alongside amylase/lipase.
- 🍷 Liver Disease: Elevated in hepatitis, ischaemia, cirrhosis.
- 💧 Renal Disease: Cell injury in acute kidney injury or glomerulonephritis.
- 💪 Muscle Injury: Trauma, rhabdomyolysis, or myopathies.
🩺 Clinical Pearls
- 🌍 LDH is a non-specific marker → always interpret in context with other tests (troponin, CK, LFTs, renal profile).
- 📊 Persistently high LDH in cancer patients may indicate disease relapse or poor prognosis.
- 🧪 In haemolysis, raised LDH often accompanies ↑ reticulocytes, ↑ unconjugated bilirubin, ↓ haptoglobin.
