What this test measures
α-HBDH activity is dominantly contributed by LDH-1 (which has high affinity for alpha-ketobutyrate). Total LDH has 5 isoenzymes — LDH-1 (heart, red cells), LDH-2 (heart, red cells, lymph), LDH-3 (lungs, lymph), LDH-4 (kidney, placenta), LDH-5 (liver, skeletal muscle). The α-HBDH / total LDH ratio approximates the contribution of LDH-1 and LDH-2 — used historically to confirm myocardial injury and haemolysis.
Why it matters
In modern Indian practice, α-HBDH is largely obsolete for cardiac diagnosis (replaced by high-sensitivity troponin) but still ordered occasionally to support: (1) Haemolysis — high α-HBDH with high LDH, low haptoglobin, raised indirect bilirubin. (2) Megaloblastic anaemia (massive intramedullary haemolysis). (3) Some haematologic and renal malignancies. (4) Confirming LDH source pattern in cancer monitoring.
How to prepare
No fasting required. Avoid haemolysis (a major preanalytical artefact — red cell lysis releases LDH and α-HBDH). Disclose recent intense exercise (raises both LDH and α-HBDH), strenuous fasting, or any haematologic / haemolytic disease history.
Markers & reference ranges
Reference ranges below are typical adult values. Your lab's reported range may differ slightly based on the assay platform and patient demographics — always read your report against the range printed on it.
| Marker | Normal range | If low | If high |
|---|---|---|---|
| Alpha-HBDH (U/L)[1][2] | Adults 75 – 250 (assay-dependent) | Low α-HBDH is unusual and not clinically meaningful. | Raised α-HBDH (with raised LDH) suggests release from LDH-1 / LDH-2 sources: myocardial injury (now usually diagnosed by troponin), haemolysis (check haptoglobin, indirect bilirubin, peripheral smear), megaloblastic anaemia (massive intramedullary haemolysis), B12 deficiency, certain haematologic malignancies (CML, lymphoma), renal cell carcinoma. α-HBDH / LDH ratio > 0.6 suggests cardiac or haemolytic origin. |
α-HBDH / LDH ratio interpretation
| α-HBDH/LDH ratio | Likely source | Notes |
|---|---|---|
| < 0.55 | Hepatic / skeletal muscle (LDH-5) | Liver disease, muscle injury |
| 0.55 – 0.65 | Mixed | Non-specific |
| > 0.65 | Cardiac / haemolytic (LDH-1, LDH-2) | MI (use troponin), haemolysis, megaloblastic anaemia |
Frequently asked questions
Is this still used to diagnose heart attacks?
No — high-sensitivity troponin has fully replaced α-HBDH and LDH for MI diagnosis. α-HBDH is occasionally added in haemolysis workup.
Why is it useful in haemolysis?
Red cells are rich in LDH-1, so haemolysis (any cause — autoimmune, microangiopathic, sickle cell, mechanical) raises α-HBDH. Combined with low haptoglobin, raised indirect bilirubin, and a peripheral smear, it confirms intravascular haemolysis.
My ratio is high but I feel fine — should I worry?
Pre-analytical haemolysis during blood collection is the commonest cause of an isolated high LDH/α-HBDH with no other findings. Repeat with clean venepuncture.
Does intense exercise raise α-HBDH?
Yes — but it raises LDH-5 (muscle) more than LDH-1, so the α-HBDH/LDH ratio actually drops. The pattern helps distinguish exercise from cardiac causes.
Will B12 deficiency raise it?
Yes — megaloblastic anaemia has massive intramedullary haemolysis, raising both LDH and α-HBDH dramatically. Pattern: very high LDH, very high α-HBDH, low Hb, MCV > 100, low B12 / folate.
Related Cardiac Markers tests
Tests commonly ordered alongside ALPHA HYDROXYBUTYRATE DEHYDROGENASE, or that help interpret an unexpected result.
Sources & references
- Mayo Clinic Labs — LDH Isoenzymes · accessed 2026-05-30T00:00:00.000Z
- NIH MedlinePlus — LDH Isoenzymes · accessed 2026-05-30T00:00:00.000Z
- StatPearls — Lactate Dehydrogenase · accessed 2026-05-30T00:00:00.000Z
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