section name header

Introduction ⬇

LDH is an intracellular enzyme that is widely distributed in the tissues of the body, particularly in the kidney, heart, skeletal muscle, brain, liver, and lungs. Increases in the reported value usually indicate cellular death and leakage of the enzyme from the cell.

Although elevated levels of LDH are nonspecific, this test is useful in confirming pulmonary infarction when viewed in relation to other test findings. LDH level is also helpful in the differential diagnosis of muscular dystrophy and pernicious anemia. More specific findings may be found by breaking down the LDH into its five isoenzymes. (When LD values are reported or quoted, total LDH is meant.)

Normal Findings ⬆ ⬇

0–30 days: 135–750 U/L or 2.25–12.53 μkat/L

31 days–11 months: 160–450 U/L or 2.67–7.52 μkat/L

1–3 years: 160–370 U/L or 2.67–6.18 μkat/L

4–6 years: 145–345 U/L or 2.42–5.76 μkat/L

7–15 years: 143–293 U/L or 2.39–4.89 μkat/L

16 years and older: 105–233 U/L or 1.75–3.89 μkat/L

Normal values vary with method of testing. Check with your laboratory for reference values.

Procedure ⬆ ⬇

  1. Obtain a 5-mL venous blood sample (red-topped tube). Serum is used. Observe standard precautions.

  2. Avoid hemolysis in obtaining blood sample. Label the specimen with the patient’s name, date and time of collection, and test(s) ordered. Place the specimen in a biohazard bag.

Clinical Implications ⬆ ⬇

  1. Increased LDH (LD) occurs in the following conditions:

    1. High levels occur within 36–55 hours after MI and continue longer than elevations of serum glutamic–oxaloacetic transaminase (SGOT) or CPK (3–10 days). Differential diagnosis of acute MI may be accomplished without LDH isoenzymes.

    2. With pulmonary infarction, increased LDH occurs within 24 hours of pain onset. The pattern of normal SGOT and elevated LDH that levels off 1–2 days after an episode of chest pain is indicative of pulmonary infarction.

    3. Elevated levels of LDH are also observed in various other conditions:

      1. Heart failure

      2. Liver diseases (e.g., cirrhosis, alcoholism, acute viral hepatitis)

      3. Malignant neoplasms, cancer, leukemias, lymphoma

      4. Hypothyroidism

      5. Lung diseases

      6. Skeletal muscle diseases (muscular dystrophy), muscular damage

      7. Megaloblastic and pernicious anemias, hemolytic anemia, sickle cell disease

      8. Delirium tremens, seizures

      9. Shock, hypoxia, hypotension

      10. Hyperthermia

      11. Kidney infarct

      12. CNS diseases

      13. Acute pancreatitis

      14. Fractures, other trauma including head injury

      15. Intestinal obstruction

  2. Decreased LDH levels are associated with a good response to cancer therapy.

Interventions ⬆ ⬇

Pretest Patient Care

  1. Explain test purpose and blood-drawing procedure. Obtain recent history of MI or pulmonary infarction.

  2. Follow guidelines in Chapter 1 for safe, effective, informed pretest care.

Posttest Patient Care

  1. Have the patient resume normal activities.

  2. Review test results; report and record findings. Modify the nursing care plan as needed. Monitor for myocardial and pulmonary infarction and other diseases related to abnormal results. LD isoenzymes may be ordered.

  3. Follow guidelines in Chapter 1 for safe, effective, informed posttest care.

Interfering Factors ⬆

  1. Strenuous exercise and the muscular exertion involved in childbirth cause increased LDH levels.

  2. Skin diseases can cause falsely increased LDH levels.

  3. Hemolysis of RBCs due to freezing, heating, or shaking the blood sample will cause falsely increased LDH levels.

  4. Various drugs may cause increased or decreased LDH levels (see Appendix E).

Clinical Alert

LDH is found in nearly every tissue of the body; therefore, elevated levels are of limited diagnostic value by themselves. Differential diagnoses may be accomplished with LD isoenzyme determination. Angina and pericarditis do not produce LDH elevations