Specimen Collection

If separation of blood is delayed for more than 3h, LDH leaks from red cells and falsely elevated LDH activity levels will be seen.

Sample stability:

• 7 days at 15-25 ^o C
• 4 days at 2-8 ^o C
• 6 weeks at -20 ^o C

4.5 mL PST Blood (Preferred)

0.5 mL Paediatric Micro-PST Blood (Preferred)

5 mL Heparin Blood

4 mL Plain Blood

3.5 mL SST Blood

0.5 mL Paediatric Microsample Blood

0.5 mL Paediatric Micro-heparin Blood
Reference Intervals

Units: U/L

Reference interval: 120 - 250

Uncertainty of Measurement: 5%

Falsely high values can be caused by haemolysis or delayed separation of the sample.

Turnaround Time: Within 3 hours
Assay Method

Principle : Enzymatic

Reagents: Roche LDHI2 kit

Analyser: Cobas c502

Diagnostic Use and Interpretation

Sources of LDH:

• skeletal or cardiac muscle
• liver
• RBC
• Some tumours

The source of an elevated LDH of unknown cause can be identified by testing LDH isoenzymes.

Time course of enzyme changes after myocardial infarction

Starts to rise Peak Remain

Elevated

Myoglobin	2-4h	4-12h	15-40h
Troponin T	4-6h	12-24h	4-10d
Total CK and CKMB	4-6h	24-48h	3-5d
AST	6-8h	24-48h	4-6d
LD	12-24h	48-72h	7-12d

Contact Information

Emails to chemicalpathologist@adhb.govt.nz will receive priority attention from the on-call chemical pathologist.

If the query concerns a specific patient please include the NHI number in your email.

If email is not a suitable option, please contact the on-call chemical pathologist via Lablink (Auckland City Hospital ext. 22000 or 09-3078995).

Individual chemical pathologists may be contacted but will not be available at all times.

After-hours : contact Lablink (Auckland City Hospital ext. 22000 or 09-3078995) or hospital operator for on duty staff after hours.

Dr Samarina Musaad (Clinical Lead) : SamarinaM@adhb.govt.nz ext. 22402

Dr Cam Kyle: CampbellK@adhb.govt.nz ext 22052

Dr Weldon Chiu: WeldonC@adhb.govt.nz ext. 23427

Dr Campbell Heron: CHeron@adhb.govt.nz ext. 23427

Dr Sakunthala Jayasinghe: Sakunthala@adhb.govt.nz ext. 23427

Last updated at 15:26:00 06/01/2025