| Study | Critical Finding (Conventional Units [CU]) | Conversion Factor | Critical Finding (SI) |
|---|
| Therapeutic Drugs |
| Analgesic and Antipyretic Drugs |
| Acetaminophen | Greater than 200 mcg/mL (4 hr postingestion) | SI = CU × 6.62 | Greater than 1,324 micromol/L (4 hr postingestion) |
| Acetylsalicylic acid | Greater than 40 mg/dL | SI = CU × 0.073 | Greater than 2.9 mmol/L |
| Anticonvulsant Drugs |
| Carbamazepine | Greater than 20 mcg/mL | SI = CU × 4.23 | Greater than 85 micromol/L |
| Ethosuximide | Greater than 200 mcg/mL | SI = CU × 7.08 | Greater than 1,416 micromol/L |
| Lamotrigine | Greater than 20 mcg/mL | SI = CU × 3.9 | Greater than 78 micromol/L |
| Phenobarbital | Greater than 60 mcg/mL | SI = CU × 4.31 | Greater than 259 micromol/L |
| Phenytoin | Greater than 30 mcg/mL | SI = CU × 3.96 | Greater than 119 micromol/L |
| Primidone | Greater than 15 mcg/mL | SI = CU × 4.58 | Greater than 69 micromol/L |
| Valproic acid | Greater than 200 mcg/mL | SI = CU × 6.93 | Greater than 1,386 micromol/L |
| Antidepressant Drugs (Cyclic) |
| Amitriptyline | Greater than 500 ng/mL | SI = CU × 3.6 | Greater than 1,800 nmol/L |
| Doxepin | Greater than 500 ng/mL | SI = CU × 3.58 | Greater than 1,790 nmol/L |
| Imipramine | Greater than 500 ng/mL | SI = CU × 3.57 | Greater than 1,785 nmol/L |
| Nortriptyline | Greater than 500 ng/mL | SI = CU × 3.8 | Greater than 1,900 nmol/L |
| Protriptyline | Greater than 500 ng/mL | SI = CU × 3.8 | Greater than 1,900 nmol/L |
| Antidysrhythmic Drugs |
| Amiodarone | Greater than 2.5 mcg/mL | SI = CU × 1.55 | Greater than 3.9 micromol/L |
| Digoxin | Greater than 2.5 ng/mL | SI = CU × 1.28 | Greater than 3.2 nmol/L |
| Disopyramide | Greater than 7 mcg/mL | SI = CU × 2.95 | Greater than 20.6 micromol/L |
| Flecainide | Greater than 1 mcg/mL | SI = CU × 2.41 | Greater than 2.41 micromol/L |
| Lidocaine | Greater than 6 mcg/mL | SI = CU × 4.27 | Greater than 25.6 micromol/L |
| Procainamide | Greater than 10 mcg/mL | SI = CU × 4.25 | Greater than 42.5 micromol/L |
| N-Acetyl Procainamide | Greater than 40 mcg/mL | SI = CU × 4.25 | Greater than 170 micromol/L |
| Quinidine | Greater than 6 mcg/mL | SI = CU × 3.08 | Greater than 18.5 micromol/L |
| Antimicrobial Drugs |
| Aminoglycosides: Amikacin | Greater than 10 mcg/mL | SI = CU × 1.71 | Greater than 17.1 micromol/L |
| Aminoglycosides: Gentamicin | Peak greater than 12 mcg/mL, trough greater than 2 mcg/mL | SI = CU × 2.09 | Peak greater than 25.1 micromol/L, trough greater than 4.2 micromol/L |
| Aminoglycosides: Tobramycin | Peak greater than 12 mcg/mL, trough greater than 2 mcg/mL | SI = CU × 2.09 | Peak greater than 25.1 micromol/L, trough greater than 4.2 micromol/L |
| Tricyclic Glycopeptide: Vancomycin | Trough greater than 30 mcg/mL | SI = CU × 0.69 | Trough greater than 20.7 micromol/L |
| Antipsychotic Drugs and Antimanic Drugs |
| Haloperidol | Greater than 42 ng/mL | SI = CU × 2.66 | Greater than 112 nmol/L |
| Lithium | Greater than 2 mEq/L | SI = CU × 1 | Greater than 2 mmol/L |
| Immunosuppressants |
| Cyclosporine | Greater than 500 mcg/mL | SI = CU × 0.832 | Greater than 416 nmol/L |
| Everolimus | Greater than 15 ng/mL | SI = CU × 1.04 | Greater than 15.6 mcg/L |
| Methotrexate | Greater than or equal to 5 micromol/L | SI = CU × 1 | Greater than or equal to 5 micromol/L |
| Sirolimus | Greater than 25 ng/mL | SI = CU × 1.1 | Greater than 28 mcg/L |
| Tacrolimus | Greater than 25 ng/mL | SI = CU × 1.24 | Greater than 31 mcg/L |
| Drug Screen |
| Alcohol | Greater than 400 mg/dL | | |
| Alphabetical Listing |
| Amniotic Fluid Analysis: Lecithin/Sphingomyelin Ratio | An L/S ratio less than 1.5:1 is predictive of respiratory distress syndrome at the time of delivery | | |
| Bilirubin and Bilirubin Fractions | Adults and Children: Total bilirubin greater than 15 mg/dL; Newborns: Total bilirubin greater than 13 mg/dL | SI = CU × 17.1 | Adults and Children: Total bilirubin greater than 257 micromol/L; Newborns: Total bilirubin greater than 222 micromol/L |
| Biopsies | Assessment of clear margins after tissue excision; classification or grading of tumor; identification of malignancy | N/A | |
| Biopsy, Chorionic Villus | Identification of abnormalities in chorionic villus tissue | N/A | |
| Bioterrorism and Public Health Safety Concerns: Testing for Infectious Agents | Positive findings of suspected bacterial or viral organisms or toxins by Gram stain, culture, serology, immunochemical testing, polymerase chain reaction, or any other method. Lists of specific organisms may vary by facility; specific organisms are required to be reported to local, state, and national departments of health | N/A | |
| Bladder Cancer Markers | Positive findings may be an indication for expedited confirmatory procedures as ordered | N/A | |
| Blood Gases, Arterial | | | |
| pH | Less than 7.2 or greater than 7.6 | SI = CU × 1 | Less than 7.2 or greater than 7.6 |
| HCO3 | Less than 10 or greater than 40 mmol/L | SI = CU × 1 | Less than 10 or greater than 40 mmol/L |
| PCO 2 | Less than 20 or greater than 67 mm Hg | SI = CU × 0.133 | Less than 2.7 or greater than 8.9 kPa |
| PO 2 | Less than 40 mm Hg | SI = CU × 0.133 | Less than 6 kPa |
| Blood Typing, Antibody Screen, and Crossmatch | Note and immediately report to the health-care provider any signs and symptoms associated with a blood transfusion reaction | N/A | |
| Calcium, Blood Total | Less than 7 mg/dL or greater than 12 mg/dL | SI = CU × 0.25 | Less than 1.8 or greater than 3 mmol/L |
| Calcium, Ionized (see Calcium Total and Ionized) | Less than 3.2 mg/dL or greater than 6.2 mg/dL | SI = CU × 0.25 | Less than 0.8 or greater than 1.6 mmol/L |
| Carbon Dioxide | Less than 15 mEq/L or mmol/L; greater than 40 mEq/L or mmol/L | SI = CU × 1 | Less than 15 mmol/L or greater than 40 mmol/L |
| Carbon Monoxide | 30%–40%: dizziness, muscle weakness, vision problems, confusion, increased heart rate, increased breathing rate; 50%–60%: loss of consciousness, coma; greater than 60%: death | N/A | |
| Cerebrospinal Fluid Analysis | Positive Gram stain, India ink preparation, or culture; presence of malignant cells or blasts; elevated WBC count; Adults: Glucose less than 37 mg/dL or greater than 440 mg/dL; Children: Less than 31 mg/dL or greater than 440 mg/dL | Glucose SI = CU × 0.0555 | Positive Gram stain, India ink preparation, or culture; presence of malignant cells or blasts; elevated WBC count; Adults: Glucose less than 2.1 mmol/L or greater than 24.4 mmol/L; Children: Less than 1.7 mmol/L or greater than 24.4 mmol/L |
| Chloride, Blood | Less than 80 mEq/L or mmol/L; greater than 115 mEq/L or mmol/L | SI = CU × 1 | Less than 80 mmol/L; greater than 115 mmol/L |
| Chloride, Sweat | Greater than 60 mEq/L or mmol/L considered diagnostic of cystic fibrosis | SI = CU × 1 | Greater than 60 mmol/L considered diagnostic of cystic fibrosis |
| Creatinine, Blood | Adults: Potential critical value is greater than 7.4 mg/dL (nondialysis patient); Children: Potential critical value is greater than 3.8 mg/dL (nondialysis patient) | SI = CU × 88.4 | Adults: Potential critical value is greater than 654.2 micromol/L (nondialysis patient); Children: Potential critical value is greater than 336 micromol/L (nondialysis patient) |
| Creatinine Clearance, Urine (see Creatinine, Urine, and Creatinine Clearance, Urine) | Degree of impairment—marked: Less than 28 mL/min/1.73 m2 | SI = CU × 0.0167 | Degree of impairment—marked: Less than 0.5 mL/s/1.73 m2 |
| Cultures | Positive for various organisms including, acid-fast bacillus Mycobacterium, Campylobacter, Clostridioides difficile, Corynebacterium diphtheriae, Escherichia coli, O157:H7, group B streptococcus (GBS), Legionella, Listeria, methicillin-resistant Staphylococcus aureus, Salmonella, Shigella, vancomycin-resistant enterococcus, Vibrio, Yersinia. Viruses such as influenza, respiratory syncytial virus, rotavirus, varicella. Positive findings of bacterial or viral organisms in any sterile body fluid such as amniotic fluid, blood, pericardial fluid, peritoneal fluid, pleural fluid. Lists of specific organisms may vary by facility; specific organisms are required to be reported to local, state, and national departments of health | N/A | |
| Cytology, Sputum and Urine | Identification of malignancy | N/A | |
| Fibrinogen | Less than 80 mg/dL; greater than 800 mg/dL | SI = CU × 0.0294 | Less than 2.4 micomol/L; greater than 23.5 micromol/L |
| Glucose | Less than 40 mg/dL; greater than 400 mg/dL | SI = CU × 0.0555 | Less than 2.22 mmol/L; greater than 22.2 mmol/L |
| Gram Stain | Any positive results in blood, cerebrospinal fluid, or any body cavity fluid | N/A | |
| Hematocrit (see Hemoglobin and Hematocrit) | Adults and Children: Less than 19.8% or greater than 60%; Newborns: Less than 35% or greater than 66.9% | SI = CU × 0.01 | Adults and Children: Less than 0.2 volume fraction or greater than 0.6 volume fraction; Newborns: Less than 0.35 volume fraction or greater than 0.67 volume fraction |
| Hemoglobin (see Hemoglobin and Hematocrit) | Adults and Children: Less than 6.6 g/dL or greater than 20 g/dL; Newborns: Less than 12 g/dL or greater than 22.3 g/dL | SI = CU × 10 | Adults and Children: Less than 66 g/L or greater than 200 g/L; Newborns: Less than 120 g/L or greater than 223 g/L |
| Iron (see Iron Studies) | Serious toxicity: Greater than 400 mcg/dL; lethal: greater than 1,000 mcg/dL | SI = CU × 0.179 | Serious toxicity: Greater than 71.6 micromol/L; lethal: greater than 179 micromol/L |
| Ketones, Blood and Urine | Strongly positive test results for ketones | N/A | |
| Lactic Acid | Adults: Greater than 31 mg/dL; Children: Greater than 37 mg/dL | SI = CU × 0.111 | Adults: Greater than 3.4 mmol/L; Children: Greater than 4.1 mmol/L |
| Lead | Levels equal to or greater than 3.5 mcg/dL indicate exposure above the reference level. | SI = CU × 0.0483 | Levels equal to or greater than 0.24 micromol/L indicate exposure above the reference level. |
| Levels equal to or greater than 45 mcg/dL may require chelation therapy. Levels greater than 70 mcg/dL may cause severe brain damage and result in death. | | Levels equal to or greater than 2.2 micromol/L require chelation therapy. Levels greater than 3.3 micromol/L may cause severe brain damage and result in death. |
| Magnesium, Blood | Less than 1 mg/dL; greater than 9 mg/dL | SI = CU × 0.4114 | Less than 0.4 mmol/L; greater than 3.7 mmol/L; |
| Methemoglobin (see Hemoglobin Electrophoresis and Abnormal Hemoglobins) | Signs of central nervous system depression can occur at levels greater than 45%; death may occur at levels greater than 70% | N/A | |
| Osmolality, Blood | Less than 265 mOsm/kg; greater than 320 mOsm/kg | SI = CU × 1 | Less than 265 mmol/kg; greater than 320 mmol/kg |
| Partial Thromboplastin Time, Activated | Greater than 75–100 sec | N/A | |
| Pericardial Fluid Analysis | Positive culture findings in any sterile body fluid | N/A | |
| Peritoneal Fluid Analysis | Positive culture findings in any sterile body fluid | N/A | |
| Phosphorus, Blood | Less than 1 mg/dL; greater than 8.9 mg/dL | SI = CU × 0.323 | Less than 0.3 mmol/L; greater than 2.9 mmol/L |
| Platelet Count | Less than 30 × 103/microL; greater than 1,000 × 103/microL | SI = CU × 1 | Less than 30 × 109/L; greater than 1,000 × 109/L |
| Pleural Fluid Analysis | Positive culture findings in any sterile body fluid | N/A | |
| Potassium, Blood | Adults and Children: Less than 2.5 mEq/L or mmol/L; greater than 6.2 mEq/L or mmol/L; Newborns: Less than 2.8 mEq/L or mmol/L; greater than 7.6 mEq/L or mmol/L | SI = CU × 1 | Adults and Children: Less than 2.5 mmol/L; greater than 6.2 mmol/L; Newborns: Less than 2.8 mmol/L; greater than 7.6 mmol/L |
| Prothrombin Time and International Normalized Ratio | PT greater than 40 sec; INR greater than 5 | N/A | |
| Pseudocholinesterase and Dibucaine Number (see Cholinesterases: Acetylcholinesterase, Pseudocholinesterase, and Dibucaine Number) | A positive result indicates that the patient is at risk for prolonged or unrecoverable apnea related to the inability to metabolize succinylcholine | N/A | |
| RBC Morphology and Inclusions (see RBC Count, Indices, Morphology, and Inclusions) | The presence of abnormal cells, other morphological characteristics, or cellular inclusions may signify a potentially life-threatening or serious health condition and should be investigated. | N/A | |
| Examples are the presence of sickle cells, moderate numbers of spherocytes, marked schistocytosis, oval macrocytes, basophilic stippling, nucleated RBCs (if the patient is not an infant), or malarial organisms | | |
| Rubella Testing | A nonimmune status in pregnant patients may present significant health consequences for the developing fetus if the mother is exposed to an infected individual | N/A | |
| Sodium, Blood | Less than 120 mEq/L or mmol/L; greater than 160 mEq/L or mmol/L | SI = CU × 1 | Less than 120 mmol/L; greater than 160 mmol/L |
| Synovial Fluid Analysis | Positive culture findings in any sterile body fluid | N/A | |
| Thyroxine, Total | Less than 2 mcg/dL; greater than 20 mcg/dL | SI = CU × 12.9 | Less than 26 nmol/L; greater than 258 nmol/L |
| Tuberculosis: Skin and Blood Tests | Positive results (indicative of past or present exposure to Mycobacterium tuberculosis | N/A | |
| Urea Nitrogen, Blood | Greater than 100 mg/dL (nondialysis patients) | SI = CU × 0.357 | Greater than 35.7 mmol/L (nondialysis patients) |
| Uric Acid, Blood | Greater than 13 mg/dL | SI = CU × 0.059 | Greater than 0.8 mmol/L |
| Urinalysis | Presence of uric acid, cystine, leucine, or tyrosine crystals; the combination of grossly elevated urine glucose and ketones is also considered significant | N/A | |
| Vitamins A, D, E, K (see Vitamin Studies) | Vitamin toxicity can be as significant as problems brought about by vitamin deficiencies. The potential for toxicity is especially important to consider with respect to fat-soluble vitamins, which are not eliminated from the body as quickly as water-soluble vitamins and can accumulate in the body | N/A | |
| WBC Count, Blood Smear, and Differential | Less than 2 × 103/microL; greater than 40 × 103/microL; absolute neutrophil count less than 0.5 × 103/microL | SI = CU × 1 | Less than 2 × 109/L; greater than 40 × 109/L; absolute neutrophil count less than 0.5 × 109/L |