Critical tests are called to the caregiver regardless of the result obtained. The Clinical Laboratory does not currently define any tests as “critical.”


Click here to review the University of Colorado Hospital “Critical Results/Values Notification and Documentation” policy.

Less than: <Less than or equal to: ≤
Greater than: >Greater than or equal to: ≥
Absolute Neutrophil Count
See table below for Oncology exceptions.
<1.0 x 109/L 
Acetaminophen ≥40.0 ug/mL
AFB Culture or Smear, Cerebrospinal Fluid Positive
Amikacin trough >10 ug/mL
Antibody, red blood cell, unexpected and clinically significant, STAT and surgical blood transfusions Positive
Antithrombin III Activity<20 U/dL 
APTT >159 seconds
Bicarbonate (HCO3), arterial blood gas≤12 mmol/L≥40 mmol/L
Bilirubin, total (newborns 0-1 month) ≥20.0 mg/dL
Blood Culture Positive
Blood culture, blood product associated with transfusion reaction Positive
Blood parasites (Malaria, Babesia, Microfilaria, Trypanosomes, etc.) Positive
Calcium<6.0 mg/dL>12.0 mg/dL
Carbamazepine ≥15.0 ug/mL
Carboxyhemoglobin ≥12%
CO2≤9 mmol/L≥40 mmol/L
CO2, total (tCO2), arterial blood gas≤12 mmol/L≥40 mmol/L
Coagulation Factor Activities ( II, V, VII, VIII, IX, X, XI, XII and vWF)<20 U/dL 
Cryptococcal Antigen Positive
Culture, following sources:


  • Any source (Acanthamoeba, Naegleria, Balamuthia, Nocardia, partial acid fast organisms only)
  • Blood
  • CSF
  • Eye (Gram negative rod only)
Cyclosporine >400 ng/mL
Digoxin ≥3.0 ng/mL
Ethanol ≥400 mg/dL
Ethylene glycol ≥3 mg/dL
Factor Inhibitors >0.5 U/mL
Fibrinogen<100 mg/dL 
Gentamicin trough ≥2.00 ug/mL
Gentamycin peak ≥12.0 ug/mL
Gentamycin random ≥12.0 ug/mL
Glucose≤40 mg/dL≥500 mg/dL
Gram Stain, following sources:


  • Body fluids (ascites, CSF, paracentesis, peritoneal)
  • Tissues (brain, epidural, eye, heart)
  • Specimens submitted from Surgery
  • Blood products associated with  transfusion reaction
See table below for Oncology  exceptions.
<24 %>60%
See table below for Oncology exceptions.
<8 gm/dL>20 gm/dL
Heparin Associated Platelet Antibodies Positive
Heparin Level >1.2 U/mL
INR ≥6.0
Ionized Calcium≤0.75 mmol/L≥1.66 mmol/L
Isopropanol 5 mg/dL
Ketones (infants under 6 months old) 3+
Lidocaine >9 ug/mL
Lithium > 1.5 mmol/dL
Low Molecular Weight (LMW) Heparin Level ≥1.7 U/mL
Magnesium≤1.2 mg/dL≥6.0 mg/dL
Methanol >5 mg/dL
Methemoglobin ≥3.0%
Methotrexate 24 Hour: >5 µmol/L


48 hour: >0.5 µmol/L

pCO2≤20 mmHg≥70 mmHg
PCR, following sources (viruses):


  • CSF
  • Blood (HSV, VZV, Parvovirus, Enterovirus)
  • Amniotic
  • Peritoneal
  • Pleural fluid
  • Eye including conjunctiva, aqueous vitreous
  • Tissue biopsy other than skin
Pentobarbital >50 ug/mL
PH, Arterial≤7.200≥7.600
Phenobarbital ≥50.0 ug/mL
Phenytoin ≥30.0 ug/mL
Phenytoin, Free ≥4.0 ug/mL
Phosphorus≤1.0 mg/dL 
Plasminogen<20 U/dL (>6 months)


<10 U/dL (0-6 months)

See table below for Oncology exceptions.
<50 x 109/L>600 x 109/L

PO2, Arterial

≤39 mmHg 
Potassium≤2.5 mmol/L≥6.4 mmol/L
Propylene glycol ≥5 mg/dL
Protein C Activity<20 ug/dL (>4 years)


<10 ug/dL (0-4 years)

Protein C Clot<20 ug/dL 
Protein S Clot<20 ug/dL 
Protein S Free<20 ug/dL 
Protein S Total<20 ug/dL 
Reducing Substances (infants under 6 months old) Positive
Salicylate ≥40.0 mg/dL
Sirolimus >30 ng/mL
Sodium≤120 mmol/L≥160 mmol/L
Tacrolimus >25 ng/mL
Theophylline ≥30.0 ug/mL
Thiocyanate >50 ug/mL
Tobramycin trough ≥2.0 ug/mL
Transfusion reaction investigation, hemolytic Positive
Triglycerides ≥1500 mg/dL
Triglycerides (Dermatology Clinic only) ≥800 mg/dL
Valproic Acid ≥150.0 ug/mL
Vancomycin, random and peak ≥80.0 ug/mL
Vancomycin, trough ≥35.0 ug/mL
Viral culture, following sources:


  • CSF
  • Blood
  • Amniotic
  • Peritoneal
  • Pleural
  • Eye (conjunctiva, aqueous vitreous)
  • Tissue biopsy other than skin
 Positive for CMV, HSV, VZV, or Enterovirus
Viral culture, source BAL Positive for CMV, HSV, or VZV
See table below for Oncology exceptions.
<1.5 x 109/L>30 x 109/L

Critical Values – Oncology Patients Only

Results called when criteria metResults are always called
<1.5 x 109/L<1.0 x 109/L<25 x 109/L<7 gm/dL<21%
>30 x 109/L >600 x 109/L>20 gm/dL>60%

WBC and ANC (Absolute Neutrophil Count) are called to Oncology healthcare providers when:

  1. It is the first time the critical value is detected on the patient.
  2. The patient has not had a similar critical value within the previous 24 hours.
  3. The test was not ordered in the previous 24 hours.
  4. The previous result within 24 hours was not a critical value. (The patient’s result has changed from a critical value to a non-critical value, then back to a critical value.)

Positive test results considered significant, but not defined as critical will be called to the care provider on the same day that the results are available. These results are:

  • D-dimer (Outpatients only; excludes patients in Emergency Department) ≥ 500 ng FEU/mL
  • Positive AFB smears
  • Positive AFB cultures other than M. gordonae
  • Positive Coccidioides immitis, Blastomyces dermatidis, or Histoplasma capsulatum DNA probes
  • Positive cultures for bacteria and fungus from body fluids and tissues (normally sterile sites)