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Critical Test Results and Laboratory Values

The following lists the laboratory tests with critical test results. Critical test results are informed by telephone to the requesting physician and the communication recorded in the laboratory test report and in the laboratory information system.

Clinical Biochemistry

Potassium< 2.5 or > 5.7 mmol/L
< 120 or > 160 mmol/L
Calcium< 1.75 or > 3.25 mmol/L
Glucose < 2.5 or > 25.0 mmol/L
pH (blood gas) < 7.1 or > 7.6
Calcium, ionised< 0.80 or > 1.60mmol/L
Digoxin > 2.4 µg/L
Theophylline > 20 mg/L
ParacetamolInform all resultsmg/L
SalicylateInform all resultsmmol/L
Ketone, blood> 1.4mmol/L
Lithium> 2.0mmol/L
Bilirubin (neonates only) > 299µmol/L
Amikacin> 35mg/L
Gentamicin> 15mg/L
Phenobarbital> 40 mg/L
Phenytoin> 20mg/L
Valproic acid > 100mg/L
Vancomycin > 80mg/L


APTT> 100seconds
INR> 5.0
Haemoglobin (for Adult) < 6.0 or > 20.0g/dL
Haemoglobin (Newborn) < 6.0 or > 25.0 g/dL
WBC< 1.0 or > 50.0 x 109/L
Platelets< 20 or > 800 x 109/L
Malarial ParasitesPositive
Fibrinogen< 0.9 or > 7.8g/L
New cases of leukaemia
Combination of strong positives (++) for glucose and ketones
when dipstick is ordered


  1. First time AFB smear positive specimens
  2. Microscopic examination of positive blood culture broths  
  3. VZV IgM, VZV antigen positive in pregnant women at term, newborns, immunocompromised patients, infected Healthcare Worker (HCW) / patients in contact with immunocompromised patients/newborns, adults with pneumonia
  4. HSV antigen, HSV IgM positive in viral encephalitis, newborns, pregnant women in labour, immunocompromised patients
  5. Antibody positive to any neurotropic virus – when a titer is ≥ 8 in a CSF sample
  6. Sars-CoV IgM/ Sars-CoV isolation/ MERS-CoV isolation/ Influenza A (H5) in any new case


  1. All positive results for cerebrospinal fluid
  2. Positive result for SARS Coronavirus PCR
  3. Positive result for Avian influenza H5N1 PCR or H7N9 PCR
  4. Positive result for MERS coronavirus PCR