Houston Methodist. Leading Medicine.
Houston Methodist. Leading Medicine

Critical Values

Critical Values

Critical values are those results that indicate a high risk of morbidity or mortality in the absence of rapid intervention to treat the abnormal value or its underlying cause. The laboratory will immediately notify the physician, or other clinical personnel responsible for patient care, when the following test results fall within critical ranges. Critical Laboratory results are always reported by telephone.

Test Name
Units
Call Values
Any Referral Lab Test All critical values reported to us from our reference labs, including ARUP.
Acetaminophen μg/mL >140.0
Amikacin
    trough
    peak

μg/mL
μg/mL

≥8.1
≥35.1
Bilirubin, Neonatal mg/dL ≥12.0
Blasts % First time any are present each patient encounter
Blood Cultures All positive
Blood Gases
    apH
    apCO2
    apO2


mm Hg
mm Hg

≤7.20; ≥7.60
≤20; ≥60
≤50
Calcium mg/dL ≤6.5; ≥13.0
Calcium Ionized mmol/L ≤0.75; ≥1.50
Carbamazepine (Tegretol®) μg/mL ≥12.1
Carbon Dioxide (CO2) mEq/L ≤14; ≥41
Carboxyhemoglobin (COHb) % All
Cell Count, Spinal Fluid WBC/mm3 >50 (in absence of bloody tap); Abnormal cells present (blasts, lymphoma, carcinoma, etc); organism present
Chloride (CI) mEq/L ≤75; ≥121
Cord Blood Direct Antiglobulin Positive
CSF Cultures All positive
Cyclosporine ng/mL ≥800
Digoxin ng/mL ≥3.0
Fetal Fibronectin All
Fibrinogen mg/dL ≤ 100
Free Phenytoin μg/mL ≥3.0
Free T4 ng/dL ≥5.1
FTA All reactives on mothers and newborns
Gentamicin
    trough
    peak

μg/mL
μg/mL

≥2.1
≥12.1
Glucose, Spinal Fluid mg/dL <40; ≥250
Glucose, Newborn mg/dL ≤30; ≥250
Glucose, Adult mg/dL ≤45; >400
Hemoglobin (Hgb) g/dL ≤7.0
Lactic Acid mmol/L ≥3.5
Lidocaine μg/mL ≥9.0
Lithium (Li) mEq/L ≥1.51
Magnesium (Mg) mg/dL ≤1.0; ≥4.5
Methemoglobin (MetHb) % All
Osmolality mOsm/kg ≤250; ≥320
Partial Thromboplastin Time (PTT) seconds ≥100
Phenobarbital μg/mL >60
Phenytoin (Dilantin®) μ/mL >40.0
Phosphorus mg/dL ≤0.9; ≥9.0
Platelet Count (PLT) K/μL ≤20; or ≥800
Potassium (K) mEq/L ≤3.0; ≥6.0
INR ≥5.0
PTH IO pg/mL All
Quantitative HCG mIU/mL OR only
RPR - Heelstick All reactive
Salicylate mg/dL >30.0
Sodium (Na) mEq/L ≤120; ≥160
T4 μg/dL ≥20
Theophylline μg/mL ≥20
Tobramycin
    trough
    peak

μg/mL
μg/mL

>2.00
≥12.00
Troponin ng/mL ≥1.50
Urinalysis (glucose & ketones are both positive) ≥1+
Valproic Acid (Depakene®) μg/mL ≥150.0
Vancomycin
    trough
    peak

μg/mL
μg/mL

>20.0
≥80.0
White Blood Count (WBC) K/μL ≤1.0; ≥40.0

Notification List

Outpatient results will be called to the ordering provider between the hours of 8am to 5pm. Outside of these hours, results will be called the next day.

TESTS NOTIFICATION VALUES
Ammonia >90 μmol/L
Antithrombin III (AT3) <35%
CK ≥5000 units/L
Clinitest All positive results
CMV Antigenemia All positive
EBV by PCR All positive results on CSF Specimens
Heparin Antibody All positive
Hepatitis A Antibody IgM All positive
Hepatitis B Surface Antigen Final results reactive (Call nursing unit and inpatient dialysis)
HSV by PCR All positive results on CSF Specimens
Lactic Acid, Spinal Fluid All
Lipase ≥1000 Units/L
Methotrexate All
Protein, Spinal Fluid ≥200 mg/dL
Protein, Total ≤3.9 g/dL; ≥10.1 g/dL
Triglycerides ≥800 mg/dL
Uric Acid ≥15 mg/dL
VDRL All reactive results