Abbott i-STAT 1 System Manual page 531

Whole blood
Sample
A
B
C
Plasma
Sample
A
B
C
A+B
B+C
A+C
Test Limitations
This assay is capable of detecting whole molecule (intact) hCG as well as free β-hCG subunits.
The i-STAT Total β-hCG assay is intended for use in the early detection of pregnancy only and should
not be performed for any other purpose.
Elevated hCG levels have been associated with some abnormal physiological states such
as gestational trophoblastic disease and nontrophoblastic neoplasms, including transitional
cell carcinoma of the bladder and urinary tract, renal cancer, prostate cancer, cancers of the
gastrointestinal system, neuroendocrine tumors, lung cancer, breast cancer, gynecological cancers,
and hematological cancers.
abnormal states. Persistent low levels of hCG (e.g., <50 IU/L) may be present one to five years
preceding malignant gestational trophoblastic disease.
unnecessary medical treatment and surgery, including chemotherapy and hysterectomy, when hCG
results were used in the diagnosis of abnormal states.
For diagnostic purposes, hCG results should always be used in conjunction with other data, e.g.,
patient's medical history, symptoms, results of other tests, clinical impressions, etc. β-hCG cannot be
used alone to establish the diagnosis of ectopic pregnancy.
always be used and interpreted only in the context of the overall clinical picture.
Detection of very low levels of hCG does not rule out pregnancy.
apparently healthy, nonpregnant subjects.
48 hours in a normal pregnancy,
retested after 48 hours.
Specimens from post-menopausal women may elicit weak positive results due to low hCG levels
unrelated to pregnancy. With a weak positive result, it is good laboratory practice to resample and
retest after 48 hours.
Because of the high degree of sensitivity of the assay, positive results during the initial days after
conception may later be negative due to natural termination of the pregnancy. Natural termination
occurs in 22% of clinically unrecognized pregnancies and 31% of pregnancies overall.
laboratory practice to resample and retest weak positive results after an additional 48 hours.
Rev. Date: 24-Jan-17
Concentration
(IU/L)
104.1
288.9
899.8
Concentration Diluted Concentration
(IU/L)
88.8
298.0
971.6
-
-
-
Results of this test should not be used in the diagnosis of these
15,16
Because hCG values double approximately every
19,20
patients with very low levels of hCG should be resampled and
18
Art: 730474-01D
Diluted Concentration
IU/L
52.9
132.0
467.2
IU/L
-
-
-
203.4
655.3
532.2
There have been reports of people receiving
17
The i-STAT total β-hCG results should
9,10
Low levels of hCG can occur in
18
% Recovery
101.8%
91.4%
103.8%
% Recovery
-
-
-
105.2%
103.2%
100.4%
It is good
21
β-hCG
- 5