Reference Ranges & Critical Values
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REFERENCE RANGES
Reference Ranges (“normal limits”) are usually determined by taking either the lowest and highest values (range) of results obtained on a normal population, the mean 2 standard deviations (S.D.) of the values obtained on a large population or the central 95% range. Thus at least 5% of healthy subjects will have values outside the reference range (“false positives”). The proportion of false positives may be even greater when the patient population is not closely matched to the control subjects with respect to age, sex, ethnic group, and other factors.
The reference range for each test is listed in the ALPHABETICAL LIST OF TESTS section. (Check Index). Reference ranges for common tests are in printed list form, available at the Administrative Office of the clinical lab. This list will be updated periodically. These reference ranges apply specifically to the SFGH Clinical Laboratory and the patients we serve.
A NOTE ABOUT SI UNITS
The SI System (“Système International d’Unités”) is a “coherent” system of metric units developed around 1970. Its purpose is to standardize and simplify the units of measurement and eliminate the confusion surrounding the many variants of “metric” units that have developed since the meter was defined in 1800.
The World Health Organization recommended the SI system to the medical community in 1977, and most of the world has already adopted it. In the United States, acceptance has been much slower. For your convenience, both traditional units and SI units are listed in the following table. Further information about the SI system is available upon request from the Clinical Laboratory Director's office, NH 2M2, x 8588.
Reference Ranges for Common Laboratory Tests
-
CONSTITUENT
REFERENCE RANGES*
SI UNITS (if not already reported in SI Units)
Blood, Plasma, or Serum tests
Albumin
See specific test information
ALT
M:10-40
F: 7-35
U/L
Anion gap (No K)
7-16
mmol/L
AST
10-41
U/L
B-type natriuretic peptide (BNP)
<100
pg/mL
<7.0
pmol/L
β-hydroxybutyrate
0.02-0.27
mmol/L
Bilirubin, total
0.1-1.2
mg/dL
1.7-20.5
mcmol/L
Bilirubin, Direct
0.1-0.3
mg/dL
1.7-5.1
mcmol/L
Blood Gas, Arterial
See specific test information
Calcium
8.6-10.5
mg/dL
Calcium, Ionized
1.12 – 1.32
mmol/L
Chloride
98-107
mmol/L
Cholesterol
<200
mg/dL
<5.17
mmol/L
CO2
22-29
mmol/L
Cortisol
See specific test information
Creatinine
0.6-1.3
mg/dL
53-115
mcmol/L
Ferritin
See specific test information
Glucose, Fasting
70-99
mg/dL
3.86-5.45
mmol/L
Glucose, Random
70-139
mg/dL
3.86-7.66
mmol/L
Hepatitis A
IgM Antibody
Negative
Hepatitis Bs Antigen
Negative
Hepatitis Bs Antibody
Negative
Hepatitis B Core Antibody
Negative
HCG
<5
U/L
Ionized Calcium
See Calcium, Ionized above
Iron
M: 65-175
F: 50-170
mcg/dL
11.64-31.34
8.96-30.45
mcmol/L
Iron% Saturation
16-60
%
LD
100-190
U/L
Lead
<10
mcg/dL
<0.48
mcmol/L
Lipase
7-58
U/L
Magnesium
1.7-2.4
mg/dL
0.70-0.99
mmol/L
Osmolality
275-295
mOsm/kg
Phosphatase, Alk.
M: 53-128
F: 42-98
U/L
Phosphorus
2.5-4.5
mg/dL
0.81-1.45
mmol/L
Potassium
3.5-5.1
mmol/L
Pregnancy test
Negative
Protein, total
6.4-8.3
g/dL
64-83
g/L
Sodium
136-145
mmol/L
Triglyceride
<150
mg/dL
<1.69
mmol/L
TSH-3rd Generation
0.37-4.42
mcIU/mL
Thyroxine, Free
0.65-1.80
ng/dL
8.4-23.2
pmol/L
Triiodothyronine, Free
2.30-4.20
pg/mL
3.54-6.47
pmol/L
Urea Nitrogen
6-20
mg/dL
2.1-7.1
mmol/L
Uric Acid
M: 3.5-8.5
F: 2.5-7.5
mg/dL
208-506
149-446
mcmol/L
Vitamin B12
236-888
pg/mL
174-655
pmol/L
Hematologic Values
Hemoglobin, Men
13.3-17.7
g/dL
133-177
g/L
Hemoglobin, Women
11.7-15.7
g/dL
117-157
g/L
Hematocrit, Men
39.8-52.2
%
0.40-0.52
Hematocrit, Women
34.9-46.9
%
0.35-0.47
Red Blood Cell Count:
Men
4.40-5.90 x 106/mcL
4.4-5.9 x 1012/L
Women
3.80-5.20 x 106/mcL
3.8-5.2 x 1012/L
MCV
80-100
fl
80-100
fl
Reticulocyte Count
0.5-2.0
%
0.005-0.02
Reticulocyte, Absolute
20-100
k/mcL
Sedimentation Rate (Westergren)
Children
0-10
mm/h
< Age 50, Men
0-15
mm/h
< Age 50, Women
0-20
mm/h
>Age 50, Men
0-20
mm/h
> Age 50, Women
0-30**
mm/h
Leukocytes
White Blood Cell Count (WBC)
3.9-11.7 x 103/mcL
3.9-11.7 x 1012/L
Platelets
Platelet Count
150-400 x 103/mcL
150-400 x 109/L
Coagulation Tests
Fibrinogen
170-440***
mg/dL
Fibrin D-Dimer
< 400
ng/mL
< 0.4
mg/L
Prothrombin Time (PT)
<14.5***
seconds
Partial Thrombin Time (APTT)
< 37.6***
seconds
Drug Levels - Therapeutic†
Acetaminophen
10-30
mg/L
66-199
mcmol/L
Carbamazepine (Tegretol)
4.0-10.0
mg/L
17-42
mcmol/L
Digoxin
0.5-2.0
mcg/L
0.6-2.6
nmol/L
Gentamicin‡
peak 5.0-10.0
trough 1.0-2.0
mg/L
mg/L
10.5-20.9
2.1-4.2
mcmol/L
Lithium
0.5-1.5
mmol/L
Phenobarbital
15.0-40.0
mg/L
65-172
mcmol/L
Phenytoin (Dilantin)
10.0-20.0
mg/L
40-79
mcmol/L
Salicylate
< 25
mg/dL
< 1.81
mmol/L
Theophylline
10.0-20.0
mg/L
55.5-111
mcmol/L
Tobramycin‡
peak 5.0-10.0
trough 0.5-2.0
mg/L
mg/L
10.7-21.4
1.07-4.3
mcmol/L
Valproic Acid
50-100
mg/L
347-693
mcmol/L
Vancomycin ‡
peak 20-40
trough 5-15
mg/L
10-24
3.5-10.4
mcmol/L
Urine Tests
Calcium
50-300
mg/24 hr
12.5-74.9
mmol/24 hr
Chloride
140-250
mmol/24 hr
Creatinine
0.8-2.0
g/24 hr
7.1-17.7
mmol/24 hr
Creatinine Clearance
90-130
mL/min/ 1.73m2
0.87- 1.25
mL/s/m2
Glucose
< 0.5
g/24 hr
< 2.8
Mmol/24 hr
Osmolality
50-1200
mOsm/kg
Phosphorus
0.4-1.3
g/24 hr
12.9-42.0
mmol/24 hr
Potassium
25-125
mmol/24 hr
Protein, total
< 0.16
g/24 hr
Sodium
40-220
mmol/24 hr
Urea Nitrogen
12-20
g/24 hr
4.3-7.1
mmol/24 hr
Uric Acid
0.25-0.75
g/24 hr
1.49-4.46
mmol/24 hr
Spinal Fluid (CSF)
Glucose
60-80
% blood level
Protein, total
15-45
mg/dL
150-450
mg/L
* Adult values unless otherwise specified.
** > Age 65, may exceed 40 mm/h.
*** May vary depending on reagent lot number.
† Typical maintenance levels. Actual values differ in each individual.
‡ Therapeutic ranges not established for random sampling
When the laboratory becomes aware of a critical value, i.e., an extreme and possibly life-threatening value, we will call the requesting physician or patient care unit immediately. It is essential that the correct clinic/ward location is provided on the requisition to facilitate notification of critical values. (Note: There may be some delay between submission of a routine specimen and telephone notification, as the abnormal result may be identified only after the entire analytical run has been completed and reviewed.) The following values have been adopted in communication with the medical staff of SFGHTC and are reviewed annually by the Hospital's Medical Executive Committee.
|
Constituent |
Conventional Units |
SI Units |
||
|
Acetaminophen |
> 50 |
mg/L |
> 331 |
mcmol/L |
Blood Gases, Arterial |
|
pH |
< 7.20 or > 7.55 |
|
||
|
PCO2 |
< 25 or > 65 |
mm Hg |
|
|
|
PO2 |
< 40 |
mm Hg |
|
|
|
0 to 30 days |
< 40 or > 100 |
mm Hg |
|
Blood Gases, Arterial and Capillary, Infant |
|
pH |
< 7.20 or > 7.55 |
|
||
|
PCO2 |
< 25 or > 65 |
mm Hg |
|
|
|
Base Deficit, 0 to 30 days, only |
> 10 |
mmol/L |
|
Blood Gases, Venous and Arterial, Cord Blood |
|
pH |
< 7.0 |
|
||
|
Base Deficit |
> 10 |
mmol/L |
|
|
|
Calcium |
< 6.5 or > 13.5 |
mg/dL |
< 1.62 or > 3.37 |
mmol/L |
|
Calcium, ionized |
< 0.8 or > 1.55 |
mmol/L |
|
|
|
Carbamazepine |
> 15 |
mg/L |
>63.5 |
mcmol/L |
|
CO2, Total |
< 15 or > 40 |
mmol/L |
|
|
|
Digoxin |
> 2.0 |
mcg/L |
> 2.6 |
nmol/L |
|
Ethanol * |
> 400 |
mg/dL |
> 87 |
nmol/L |
|
Fibrinogen |
< 75 |
mg/dL |
|
|
|
Gentamicin |
> 12.0 |
mg/L |
25.1 |
mcmol/L |
|
Glucose, CSF |
< 30 or > 300 |
mg/dL |
< 1.65 or > 16.53 |
mmol/L |
|
Glucose |
< 50 or > 500 |
mg/dL |
< 2.76 or > 27.55 |
mmol/L |
|
Glucose for neonates |
< 30 or > 170 |
mg/dL |
< 1.65 or > 16.53 |
mmol/L |
|
Hemoglobin |
< 7 or > 20 |
g/dL |
< 70 |
g/L |
|
INR |
> 4.9 |
|||
|
Lactate |
> 3.9 |
mmol/L |
|
|
|
Lithium |
> 2.0 |
mmol/L |
|
|
|
Magnesium |
< 1.0 or > 4.5 |
mg/dL |
< 0.41 or > 1.85 |
mmol/L |
|
Osmolality |
< 240 or > 320 |
mOsm/kg |
|
|
|
Phenobarbital |
> 50 |
mg/L |
> 216 |
mcmol/L |
|
Phenytoin (Dilantin) |
> 35 |
mg/L |
> 139 |
mcmol/L |
|
Phosphorus |
< 1 |
mg/dL |
< 0.32 |
mmol/L |
|
Platelets |
< 25 or > 1000 |
103/ mcL |
< 25 or > 1000 |
x109/L |
|
Potassium |
< 3.0 or > 6.0 |
mmol/L |
|
|
|
PT |
(See INR) |
|
||
|
PTT |
> 68.9 |
sec |
|
|
|
Salicylate |
> 35 |
mg/dL |
>2.53 |
mmol/L |
|
Sodium |
< 125 or > 155 |
mmol/L |
|
|
|
Theophylline |
> 30 |
mg/L |
> 167 |
mcmol/L |
|
Tobramycin |
> 12 |
mg/L |
> 47.6 |
mcmol/L |
|
Valproic Acid |
> 150 |
mg/L |
> 1040 |
mcmol/L |
|
Vancomycin |
> 80 |
mg/L |
> 55 |
mcmol/L |
|
WBC** |
< 1.5 or > 100 |
103/mcL |
< 1.5 or > 100 |
x109/L |
* As requested by Emergency Department, critical ethanols are not called.
** For each patient, only the first critical WBC every 30 days will be reported by telephone.
Unusual or potentially life-threatening microbiological findings will also be reported immediately by telephone, including positive cultures from blood, CSF, or other normally sterile body fluids.
Blood Bank will call immediately whenever there are delays expected in release or unavailability of blood components, or in case a transfusion reaction work-up suggests a serious adverse effect such as hemolysis, sepsis or transfusion-related acute lung injury (TRALI).
“Read-back” of all critical results (including both stat and critical values) reported verbally or by telephone is requested to verify values and assure accuracy, in accordance with Joint Commission’s National Patient Safety Goals.