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Updates |
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| Lp(a) |
It is widely accepted that Lp(a) is an important risk factor that may contribute to coronary artery disease (CAD) independent of other lipid or non-lipid risk factors1. Although similar to LDL, Lp(a) is not affected by dietary factors and Lp(a) determination is being recognized as a significant independent marker for assessment of the risk of coronary heart disease.
The Lp(a)’s unique composition shows sequence similarity to those of plasminogen and hepatocyte growth factor – which suggests that the role of Lp(a) in promoting the development of atherosclerosis may come from its capability to:
- Interfere in the breakdown of blood clots
- Stimulate atherosclerotic cell proliferation
ORDERING INFORMATION :
Test # 493
PHYSIOLOGY
Lp(a) is a complex macromolecule formed by the assembly of apolipoprotein (apo) B100 – containing lipoproteins composed mainly of LDL, with a carbohydrate-rich protein, apo(a). Apo(a) has a high degree of structural homology with plasminogen – a key zymogen of the coagulation cascade.
In Lp(a) particles – one molecule of apo(a) is covalently linked by a disulfide bridge with one molecule of apo B100.
Subsequent studies have shown that Lp(a) is a specific family of lipoprotein particles whose protein moiety is composed of Apo B linked to a variable mass that has not been found in any other lipoprotein.
The presence of apo(a) imparts unique physiochemical characteristics and metabolic properties to Lp(a) that distinguish it from LDL and all other lipoprotein particles.
The Lp(a) antigen was also found to be genetically determined by an autosomal dominant mode of inheritance2. Early familial studies indicated that the presence of Lp(a) is segregated in a Mendelian autosomal-dominant fashion that is determined by 2 alleles. This has firmly established that Lp(a) concentrations are strongly influenced by genetic factors3.
CLINICAL SIGNIFICANCE
Lp(a) is an independent risk factor for atherosclerotic and cardiovascular complications in both the general and uremic populations of the United States4. The wide range of different Lp(a) levels seen in most individuals is primarily due to genetic factors and may not be controllable by dietary and lifestyle changes.
However, the identification of individuals at CHD risk through the diagnostic testing of Lp(a) can play a significant role in alerting such individuals for the need to eliminate or control other high risk factors when possible.
In addition to its diagnostic value for risk assessment of cardiovascular and cerebral vascular disease- Lp(a) is also effective for management of diabetes and renal insufficiency.
DIABETES
LDL particle size abnormalities are extremely common in diabetes. Recent reviews have described that 35% of diabetics demonstrate abnormally elevated levels of Lp(a). This type of dyslipidemia has shown to present with a three-fold increased rate for cardiovascular events in diabetics based on Lp(a) alone5. Renal Disease
Markedly, elevated Lp(a) levels have been consistently reported in patients with renal disease, specifically in :
- Proteinuric patients
- receiving hemodialysis or chronic
- peritoneal dialysis
It was demonstrated that Lp(a) concentrations are significantly increased in early renal insufficiency . This condition may result in non-specific synthesis or catabolism disturbances in-patients with mild to moderate renal insufficiency6. Furthermore Lp(a) increased significantly with decreasing glomerular filtration rate.
CLINICAL USAGE SUMMARY
- Assessment of Cardiovascular and Cerebrovascular risk
- Independent atherosclerosis Risk Factor
- Detection of early renal insufficiently
- Assessment of CHD risk in diabetics
SCREENING CONDITIONS7
- Patient or family history of premature atherosclerotic heart disease
- Familial history of Hyperlipidemia
- Established CAD/CHD with normal routine lipid profile
- Hyperlipidemia refractory to therapy
- History of recurrent arterial stenosis
CLINICAL- ADDED VALUE
- Identify the 50% of Coronary Events with Normal Lipid Panels
- Identify Potential CHD Patients with a Genetic Predisposition
- Diabetic Monitoring
- Renal Dialysis Patient Monitoring
METHODOLOGY
Agglutination occurs due to an antigen-antibody reaction between Lp(a) in a sample and anti-Lp(a) antibody absorbed to latex particles. The change in absorbance is proportional to Lp(a) concentration in the sample.
The actual concentration is then determined from a calibration curve prepared from standards known.
SAMPLE COLLECTION AND PREPARATION
Collect serum using standard sampling tubes and plasma using tubes containing Li heparin, Na heparin, Na EDTA, K EDTA or citrate.
SAMPLE STORAGE AND STABILITY
The samples should be analyzed immediately or stored at -20OC
PERFORMANCE CHARACTERISTICS
- Correlation to Reference Method is r = 0.999
- CV% of 2.3% to Reference Value
- Sensitivity = 2 mg/dL
- Intra-Precision = 1.6 to 2.4%
- Reference Range: <30 mg/dL
REFERENCES
- Marcovina SM, Koshinsky ML, Hegele RA. Lp(a) and Coronary Heart Disease Risk. Curr. Cardiol. Rep. 1999; 1:105-11
- Berg K. The Lp System. [Review] Ser Haemotol 1968;1:111-36
- Morton NE, Berg K, Dahlen G, Ferrel RE, Rhoads GG. Genetics of the Lp Lipoprotein in Japanese-Americans. Genet Epidemiol. 1985;2:113-21
- Herrmann W, Quast S, Wolter K, et al. Determination of free apolipoprotein(a) in serum by immunoassay and its significance for risk assessment in patients with coronary artery disease. Clin Chem Lab Med 1999;37:22-8
- Stein JH, Rosenson RS. Lipoprotein Lp(a) excess and CHD. Arch Internal Med 1997;157:1170-1176
- Kimak, E and Solski J. Lp(a) concentration in moderate renal insufficiency. American Clinical Laboratory June 2001:p 28-30
- Futterman LG, Lemberg L, “Lp(a) - An independent risk factor for coronary heart disease. Am F Crit Care. 2001;10(1):63-67
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| D-Dimer |
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| D-Dimer: Lifting the Veil of Confusion |
These days there’s more confusion than ever about D-dimer testing. While awareness of the test’s role in indicating thrombolytic activity has undeniably improved in recent years, confusion surrounding this unique test still persists. More specifically, what type of D-dimer test is better?
To clarify, three different D-dimer assays are available: the traditional latex agglutinin test, the more sensitive ELISA assays and the equally sensitive (some would even argue more sensitive) quantitative, immunoturbidimetric D-dimer assay. While the latter test employs latex technology, it should not be confused with the less sensitive agglutinin test.
The agglutinin test is used to evaluate patients with disseminated intravascular coagulation (DIC), while the more sensitive ELISA and immunoturbidimetric D-dimer assays can additionally aid in the diagnosis of deep vein thrombosis (DVT) and pulmonary embolism (PE) – abilities the agglutinin method can not duplicate.
"Just because you’re running a D-dimer test doesn’t mean you’re getting the sensitivity you need to be able to rule out DVT or a PE,” points out David Schaffner, Ph.D., hemostasis market planning manager for Beckman Coulter. "If the intent is to diagnose DVT or PE, clinicians and laboratorians should make sure they’re running either an ELISA test or a quantitative immunoturbidimetric D-dimer
like IL Test* D-Dimer."
And even after clarifying which test the lab is using, there still might be room for improvement. Dr. Schaffner notes that clinical evidence is mounting that the immunoturbidimetric D-dimer may be even better than the ELISA method.
"In many circumstances, the immunoturbidimetric D-dimer is faster and easier to perform than ELISA, delivering highly accurate test results with up to 99 percent negative predictability and improved specificity in about seven minutes,” he says. “Contrast that with the ELISA methods, which are time consuming and require specialized equipment and training. But, at any rate, both tests are far superior to the agglutinin methods and should be used more frequently in hospitals today."
According to Schaffner, another reason to perform more D-dimer testing is, in addition to providing more accurate information, the assay will help save time and money. For example, invasive tests for DVT and PE, such as a venogram or lung scan, can cost up to $1,500 and may be risky.
"
Tests like IL Test D-Dimer provide a cost-effective alternative,"says Schaffner. "A negative test result as part of an overall testing algorithm can help physicians conclusively rule out a clot, eliminating the need for invasive and risky procedures." |
Trademark of Instrumentation Laboratory
© 1998 - 2003 Beckman Coulter, Inc. |
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| HPV DNA |
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| SOCIETY OF GYNECOLOGIC ONCOLOGISTS AND GYNECOLOGIC CANCER FOUNDATION APPLAUD FDA APPROVAL OF NEW CERVICAL CANCER SCREENING OPTION |
Chicago, April 16, 2003 --- The Society of Gynecologic Oncologists (SGO) and the Gynecologic Cancer Foundation (GCF) support the recent positive step by the Food and Drug Administration (FDA) to allow the use of HPV testing in conjunction with the Pap test for cervical cancer screening for women 30 and older.
"This is exciting news for women and their physicians," said Kenneth D. Hatch, M.D, President of SGO. "By combining these two tests, we can better determine which women are at risk of developing cervical cancer-and more important, which women are at little or no risk of the disease. If a woman has a normal Pap smear and tests negative for the HPV-the cause of virtually all cervical cancer-we can say with great assurance that she will not develop cervical cancer in the near future." Dr. Hatch is the head of the Department of Obstetrics and Gynecology at the University of Arizona.
Based on FDA approval, the American Cancer Society (ACS) recently recommended that the combination of HPV DNA testing for high-risk HPV types, together with a Pap test, be considered as an alternative for routine screening in women age 30 and older. The ACS's recommendation was based on studies using Digene's hc2TM HR HPVTM DNA Test.
Worldwide, cervical cancer affects more than 400,000 women annually and, after breast cancer, is the second most common malignancy found in women. In the United States, there are an estimated 13,000 cases of cervical cancer resulting in approximately 4,100 deaths each year.
Dr. Hatch also noted, "The FDA approval of the first significant change in how we screen women for cervical cancer in over 50 years means that we are one step closer to achieving our ultimate goal-the elimination of cervical cancer as a cause of death among women in America."
"When cervical cancer is detected early, it is virtually 100% curable. This approach to cervical cancer screening allows us the opportunity to determine which women over age 30 are at virtually no risk for cervical cancer in the next two to three years," said GCF Chairman Karl C. Podratz, MD, Ph.D. Roughly one half of the cases of cervix cancer in the U.S. occur in women who do not get regular Pap tests. "Our Foundation is committed to ensuring that women are educated about the importance of screening so that we can eliminate cervical cancer." Dr. Podratz is a professor of Obstetrics and Gynecology at the Mayo Clinic.
The SGO is a national medical specialty organization of physicians who are trained in the comprehensive management of women with malignancies of the reproductive tract. Its purpose is to improve the care of women with gynecologic cancer by encouraging research, disseminating knowledge which will raise the standards of practice in the prevention and treatment of gynecologic malignancies and cooperating with other organizations interested in women's health care, oncology and related fields.
The Society's membership is primarily comprised of gynecologic oncologists, as well as other related medical specialists such as, medical oncologists, radiation oncologists and pathologists. SGO members provide multidisciplinary cancer care including chemotherapy, radiation therapy, supportive care and surgery. More information on the SGO can be found at www.sgo.org.
The SGO formed the GCF in 1991 to ensure public awareness of gynecologic cancer prevention, early diagnosis and proper treatment. In addition, the Foundation supports research and training related to gynecologic cancers. Please access www.wcn.org to learn more about the GCF.
For further information, click on the following article.
What Women Should Know about HPV and Cervical Health |
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| BNP in Diagnosis of Heart Failure |
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Issue Date:
April 01, 2003 |
Vol. 12 •Issue 4 • Page 63
BNP in the Diagnosis of Heart Failure
B-type natriuretic peptide is a new tool for the diagnosis, prognosis and therapeutic management of heart failure patients.
By Barry I. Bluestein, PhD, MT(ASCP); Normand Despres, PhD; Alexander Belenky, PhD; Farooq Ghani, MD, PhD; and E. Glenn Armstrong, PhD
Heart failure or congestive heart failure (CHF), when heart failure patients experience a buildup of fluid, is a clinical syndrome characterized by shortness of breath, fatigue and peripheral edema caused by the heart's inability to adequately circulate blood to the body's essential organs. CHF has become so common that it is considered by some to be a new epidemic.1 This dysfunction is associated with coronary artery disease (CAD), chronic hypertension, valvular heart diseases and cardiomyopathies.
The World Health Organization now estimates that 16 million people worldwide are living with some degree of heart failure. Approximately two-thirds of those, according to the National Institutes of Health, will die within five years of their diagnosis. Eighty percent of hospitalized patients age 65 and older are admitted with a diagnosis of CHF, making it the most common diagnosis of hospitalized patients in that age group.2 As a result, more Medicare dollars are spent on heart failure than any other single diagnosis.
In the general population, the prevalence of this disorder is also considerable. In the United States, where heart failure is considered one of the fastest-growing health problems, those 40 and older have a 1-in-5 chance of developing CHF.2 The steadily increasing incidence of this disorder is due, in part, to the increasing age of the population, hypertension and number of patients surviving myocardial infarctions. The incidence of CHF is about 10 per 1,000 population after age 65 years, but 20 per 1,000 for those with hypertension, and about 50 per 1,000 for those with a previous heart attack.2
Summary
The European Society of Cardiology has approved the use of BNP measurements as an aid in the screening and diagnosis of heart failure.24 Given the growing body of literature and the availability of routine, reproducible assays, it is expected that leading cardiology associations in the United States will soon follow suit.
Many patients with CHF remain unidentified or misdiagnosed and may, therefore, not receive appropriate therapy in a timely fashion. As with most chronic diseases, identification and intervention at an early stage leads to prolonged survival and an overall improvement in the quality of life. However, as with most other clinical laboratory tests, BNP should not be used alone but in conjunction with physical exam, patient history and other noninvasive and invasive laboratory procedures. When used in this context, BNP measurements add significant value in aiding clinicians in the differential diagnosis of CHF and the selection and monitoring of therapy.
Dr. Bluestein is the principal staff scientist/technical manager for the ADVIA Centaur® BNP project, Bayer Healthcare LLC, Diagnostics Division, Lab Testing Segment R&D, Tarrytown, NY. Dr. Despres is a senior staff scientist/project manager; Dr. Belenky is a senior scientist for the ADVIA Centaur® BNP project; Dr. Ghani is manager of Clinical Trials; and Dr. Armstrong is director of Disease Focus Research and Development, Bayer Healthcare LLC.
For a list of references, contact lnace@merion.com
http://www.advanceforal.com /common/editorialsearch/viewer.aspx?FN=03apr1_alp63.html&AD=4/1/2003&FP=al
(Complete Article) |
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HPV 16/18 Genotyping |
Cervista®
HPV
16/18
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Cervista HPV
16/18 individually identifies
and differentiates high-risk
types 16 and 18
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- Identifies the
two most highly oncogenic and
persistent high-risk HPV types known
to cause high-grade cervical
neoplasia
- Facilitates
risk-stratification of patients at
greater risk for cervical disease in
order to
tailor care more appropriately
- Uses the same
technology as Cervista HPV HR, and
the test may be run from the
same 2 ml specimen
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| Celiac
Disease Testing |
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Celiac Disease Testing: PAL will soon be replacing
the conventional Gliadin IgA & IgG tests on the
Celiac Screening Panel with the Deamidated Gliadin
Peptide (DGA) antibodies IgA & IgG. DGA antibodies
feature superior sensitivity, specificity and
accuracy; and along with the t-TG antibodies,
provide the most robust non-invasive means of
investigating a possible diagnosis of celiac
disease, as well as monitoring compliance with a
gluten-free diet. |
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| Cocci
Testing |
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Cocci Testing: Effective January 1, 2011,
Physician’s Automated Laboratory, Inc. (PAL) will no
longer include the EIA methodology for Cocci IgM
screening on our Cocci Panel. New and previously
diagnosed patients will be monitored with the
immunodiffusion (ID) IgM & IgG method and the
complement fixation (CF) method, if indicated. These
changes are consistent with the protocol recently
implemented at the Kern County Public Health
Laboratory. |
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