Lactate Dehydrogenase (LDH)
LDH rises physiologically in pregnancy due to placental, hepatic, and erythrocyte turnover. Marked elevations suggest preeclampsia/HELLP, hepatic injury, hemolysis, or tissue necrosis.
| Units | Nonpregnant Adult | 1st Trimester | 2nd Trimester | 3rd Trimester |
|---|---|---|---|---|
| U/L | 115 – 211 | 78 – 433 | 80 – 447 | 82 – 524 |
| µkat/L | 1.9 – 3.5 | 1.3 – 7.2 | 1.3 – 7.5 | 1.4 – 8.8 |
Causes of LOW LDH
- Usually not clinically significant
- Rare hereditary LDHA or LDHB deficiency
- Large doses of vitamin C (assay interference)
- Dilutional effect in high plasma volume states
Causes of HIGH LDH in pregnancy
- Preeclampsia and HELLP syndrome — LDH > 600 U/L suggests hemolysis or hepatic injury
- Hemolysis (autoimmune, microangiopathic)
- Acute hepatitis, AFLP, cholestasis
- Myocardial, skeletal muscle, or renal injury
- Megaloblastic anemia (B12 or folate deficiency)
- Malignancy (lymphoma, leukemia — rare in pregnancy)
- Physiologic mild elevation of normal pregnancy
References
- Abbassi-Ghanavati M, Greer LG, Cunningham FG. Obstet Gynecol. 2009.
- Sibai BM. HELLP syndrome. Obstet Gynecol. 2004.
- ACOG Practice Bulletin No. 222: Gestational Hypertension and Preeclampsia. 2020.
- Antony AC. Megaloblastic anemias. N Engl J Med. 2018.
- Barcellini W. Hemolytic anemias in pregnancy. Blood Rev. 2020.
- Wu AHB. Clinical interpretation of LDH isoenzymes. Clin Chem. 1994.