Critical values are potentially life-threatening laboratory results that must be conveyed immediately to the physician or other health care professional so that therapeutic measures can be instituted rapidly. Main Line Health Laboratories (MLHL) maintains critical values for routine laboratory studies, therapeutic drug monitoring, microbiology testing and blood bank results.
When a critical value is encountered, MLHL automatically repeats the test in question. Once the critical value is verified, we will report the value to your office, usually by telephone. If an answering service is reached, we will inform them that you have a critical laboratory result, provide the patient's name and request that you contact our testing facility. If your answering service is authorized to accept critical values, the result will be left with the service. Communication of critical values is documented on the patient's laboratory report. If your office uses an answering machine after the close of business and no physician can be reached, MLHL will leave critical results on the answering machine and follow up the next working day.
Critical values for general laboratory tests
| Test | Low ( < or = ) | High ( > or = ) |
|---|---|---|
| Hemoglobin | 7 g/dl | 20 g/dl |
| White cell count | 2500/ mm3 | 30,000/mm3 * |
| Platelet count |
50,000/mm3 100,000/mm3 (NICU) |
1,000,000/mm3 |
| Fibrinogen | 100 mg/dl | None |
| Prothrombin Time | None | INR 6.0 |
| PTT, Activated | None | 143 sec. |
| Alcohol | None | 350 mg/dl |
| Bilirubin (newborn) | None | 15 mg/dl |
| Calcium, ionized | 0.77 mmol/L | 1.59 mmol/L |
| Calcium, serum | 6 mg/dl | 13 mg/dl |
| BUN, serum | None | 80 mg/dl** |
| Creatinine, serum | None | 5.0 mg/dl** |
| Glucose, serum | 50 mg/dl | 450 mg/dl |
| Magnesium, serum | 1.0 mg/dl | 4.0 mg/dl |
| Potassium, serum | 2.8 mEq/L |
6.0 mEq/L 7.0 mEq/L (NICU) |
| Sodium, serum | 125 mEq/L | 160 mEq/L |
| Troponin I | None | 0.4*** ng/mL |
| Total C02, serum | 10 mEq/L | 40 mEq/L |
| pCO2, arterial or capillary | 20 mmHg | 70mmHg |
| PH, arterial or capillary | 7.25 | 7.60 |
| p02, arterial or capillary | 40 mmHg | None |
| Positive initial malaria identification | ||
| Positive culture: blood, CSF, body fluid, tissue | ||
| Positive Gram stain: CSF, body fluid, tissue | ||
| Positive CSF finding (other): Cryptococcal antigen |
*Unless a known chronic leukemia patient
**Unless a known patient with renal failure
***Unless a known patient with high troponin
Critical Values for Therapeutic Drug Levels
| Drug | Therapeutic Level |
Toxic Levels (Call Results) |
|---|---|---|
|
Antibiotics |
||
| Gentamicin |
Peak: 4.0-10.0 mcg/mL Trough: 0.0-2.0 mcg/mL Single day dosing: 0.0-1.0 mcg/mL |
Peak:>10.0 mcg/mL Trough: >2.0 mcg/mL Single day dosing: >1.0 mcg/mL |
| Tobramycin | Same as above | Same as above |
| Vancomycin |
Peak: 30.0-40.0 mcg/mL Trough: 5.0-10.0 mcg/mL |
Peak: >40.0 mcg/mL Trough:>12.0 mcg/mL |
|
Anticonvulsants |
||
|
Carbamazepine (Tegretol) |
8.0-12.0 mcg/mL (single agent) 6.0-10.0 mcg/mL(multiple drugs) |
>15.0 mcg/mL >12.0 mcg/mL |
| Phenobarbital | 15.0-40.0 mcg/mL | >50.0 mcg/mL |
|
Phenytoin (Dilantin) |
10.0-20.0 mcg/mL | >25.0 mcg/mL |
| Valproic Acid | 50.0-100.0 mcg/mL | >125.0 mcg/mL |
|
Bronchodilators |
||
| Caffeine | 10.0-20.0 mcg/mL | >20.0 mcg/mL |
| Theophylline |
5.0-15.0 mcg/mL (adult) 10.0-20.0 mcg/mL (0-19 years) |
>20.0 mcg/mL >20.0 mcg/mL |
|
Cardiovascular |
||
| Digoxin | 0.5-2.0 ng/mL | >2.4 ng/mL |
| Procainamide | 4.0-10.0 mcg/mL | >10.0 mcg/mL |
| PA + NAPA levels in renal insufficiency | PA + NAPA: 5.0-30.0 mcg/mL | >30.0 mcg/mL |
| Quinidine | 1.5-5.0 mcg/mL | >5.0 mcg/mL |
|
Other Agents |
||
| Acetaminophen | 10-30 mcg/ml | >120 mcg/ml |
| Cyclosporine | 100-300 ng/ml | >300 ng/ml |
| Lithium | 0.5-1.0 mEq/L | >1.1 mEq/L |
| Salicylate | <20 mg/dl | >30 mg/dl |
Critical Values for Microbiology Testing
| Finding | Call to Physician or Designee | Call to Nursing Unit or Physician Office | Call to Infection Control Practitioner |
|---|---|---|---|
| Positive blood culture |
Xa |
Xb |
|
|
Significant CSF findings:
|
X | If gram-negative diplococci are observed on Gram stain or if N. meningitidis is recovered by culture. | |
Positive Gram stain or culture of:
|
X | ||
AFB findings:
|
X |
Xc |
X |
| Positive malaria smear |
X |
||
|
a Results are called to physician
0700 - 2200. After 2200, nursing unit is called
and the physician is notified the following
morning. b BMH and PMH only. c Only if patient is still an inpatient. |
|||
Other Noncritical Microbiology Reports Called
| Finding | Call to Physician or Designee | Call to Nursing Unit or Physician Office | Call to Infection Control Practitioner |
|---|---|---|---|
| Positive catheter tip (>15 CFU) | X | ||
| Respiratory tract specimen positive for N. meningitidis |
X |
X | |
| Identification of vancomycin resistant Enterococci |
Xa |
||
| Genital specimens—positive for group B Strep | X | ||
| Throat specimen—positive culture or antigen test for group A Strep | X | ||
| Positive culture for N. gonorrhoeae | X | ||
| Positive amplified test for N. gonorrhoeae DNA |
X |
||
| Positive amplified test for Chlamydia trachomatis DNA |
X |
||
| Positive culture for enteric pathogen | X | ||
| Positive O+P exam | X | ||
| Positive test for Clostridium difficile toxins A/B |
Xb |
||
|
a Inpatient only b PMH and BMH only |
|||
Critical Values for Blood Banking
| Critical Result | Patient's Physician Notified by Medical Director | Patient Care Unit Notified by Blood Bank Technologist | Verification and Read Back | Blood Bank Medical Director or Pathologist on Call |
|---|---|---|---|---|
| Acute hemolytic transfusion reaction |
X |
X |
X |
X |
| Detection of bacterial contamination of blood product |
X |
X |
X |
X |
| Positive DAT—specific antibody identified in eluate |
X |
X |
X |
|
| Antigen negative red cells not available on site for inpatient transfusion |
X |
X |