Specimen requirement

Plasma

Fluid

Adult patient:

 Heparin gel tube

Minimum blood volume: 5 mL

Plain bottle

Minimum volume: 10 mL

Paediatric patient:

Paediatric heparin tube

Number of vials: 1

Minimum blood volume: 1.3 mL

Authorisation code required

No

24 Hr available service

Yes

(Call extension: 3353 for express result)

No

Method

Spectrophotometry

Reference interval

Plasma:

(Source: from local population study in 2008)

Pleural fluid for Light’s discrimination criteria:

Pleural fluid is an exudate if one or more of the following criteria are met:

1. fluid TP / plasma TP > 0.5
2. fluid LDH / plasma LDH > 0.6
3. fluid LDH concentration > 2/3 of the upper limit of normal plasma range

(Source: Hooper C et al. Thorax 2015; 65 (Suppl 2): ii4 - ii17)

Clinical indication

Occasionally useful in the assessment of patients with liver disease or malignancy (especially lymphoma, seminoma, hepatic metastases); anaemia when haemolysis or ineffective erythropoiesis suspected.

Result interpretation

Increased levels are found in myocardial infarction, liver disease, haemolysis, ineffective erythropoiesis, some malignancies, muscle disease, and numerous other disease processes involving tissue damage.

Although it may be elevated in patients with skeletal muscle damage it is not a useful test in this situation.

Haemolysis during collection, delays in processing, or refrigeration of unseparated blood may cause an artefactual increase in enzyme activity.

Measurement of uncertainty

See table.

Frequency of measurement

Daily