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The Haematology & Blood Transfusion departments will make every effort to inform clinicians of grossly abnormal results which require urgent medical intervention...

Under certain circumstances it may be possible to arrange to have urgent results phoned as they become available, please contact the laboratory directly on Bleep 234 or Ext. 7892/ 7893 to inform staff of any samples that require such treatment.

Haematology critical limits

Analyte/ Index

Lower limit

Higher limit


General Haematology
Haemoglobin (g/L) ≤70g/L >200g/L  
White Cell count (WBC) ≤2.0 x109L >30.0 x109L  
Neutrophils <0.5 x109L    
Platelets ≤20 x109L >1000 x109L  
ESR   >100 mm/hr  
Malaria screen     Phone all positive screens 
Coagulation (Haemostasis)
INR   >6.0  
APTT   >100 sec  
Fibrinogen ≤1.0g/L    
Fibrin D-Dimer   >224 ng/mL  
Blood transfusion
Blood Crossmatch    

URGENT REQUESTS for ABO Group & Antibody Screens ONLY:

The minimum Turnaround Time for Fully compatible Blood is 60 minutes from the time the sample has arrived in the laboratory.

This includes time for the labelling of the Tags with the compatibility labels. This TAT may be affected by the number of the urgent requestors received at the same time.

Phone if unable to fulfil a request for crossmatched blood for whatever reason.

Direct Antiglobulin Test (DAT)   Positive  
Anti-D antibody   >4.0 iu/mL Antenatal patients only
Anti-c antibody   >4.0 iu/mL Antenatal patients only
Other antibodies   >1:16 Antenatal patients only
The following results will automatically trigger a blood film: -
Haemoglobin (g/L) ≤80g/L >180g/L* *>200g/L for neonates
MCV <65fL >105fL* *>120fL for neonates
WBC ≤2.0 x109L >30.0 x109L  
Neutrophils <1.0 x109L    
Lymphocytes   >6.0 x109L  
Eosinophils or Monocytes   >2.0 x109L  
Platelets <100 x109L >800 x109L  
Reticulocytes <10 x109L >150 x109L  


Last updated: 25 February 2015