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Topic: APTT

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	CIGNA - Partial Thromboplastin Time
		A longer-than-normal PTT or APTT can mean a lack of or low level of one of the blood clotting factors or another substance needed to clot blood.
		A longer-than-normal PTT or APTT can be caused by liver disease, kidney disease (such as nephrotic syndrome), or treatment with blood thinners, such as heparin or warfarin (Coumadin).
		The APTT is used to check treatment of people who are using heparin or other blood-thinning medicine to prevent blood clots.
	www.cigna.com /healthinfo/hw203152.html (980 words)

	02-1555 -- U.S. v. Aptt -- 01/21/2004
		Aptt argues that the criminal activity in this case was not extensive enough to qualify him for the four-level enhancement he received on his fraud offense for being the organizer or leader of criminal activity that involves five or more participants or is otherwise extensive.
		Aptt, both Murphy brothers, and two other individuals were participants in the fraud offense, and therefore applied the four-level enhancement to Mr.
		Aptt falsely represented to investors that "the houses [in Costa Rica] were being built in 21 days and sold very quickly," Mr.
	www.kscourts.org /ca10/cases/2004/01/02-1555.htm (7476 words)

	Test Descriptions - DUMC Clinical Coagulation Laboratory
		The aPTT may be prolonged due to deficiency of one or more clotting factor or due to the presence of an inhibitor that interferes either specifically or nonspecifically with the measurement of a coagulation factor.
		This is important because the aPTT tend to prolong upon incubation due to degradation of the labile clotting factors V and VIII.
		The aPTT prolongs as the activated protein C in the patient’s plasma inactivates factors V and VIII on the reagent plasma.
	www.pathology.mc.duke.edu /coag/TestDes.htm (9567 words)

	Test Descriptions - DUMC Clinical Coagulation Laboratory
		The aPTT may be prolonged due to deficiency of one or more clotting factor or due to the presence of an inhibitor that interferes either specifically or nonspecifically with the measurement of a coagulation factor.
		This is important because the aPTT tend to prolong upon incubation due to degradation of the labile clotting factors V and VIII.
		The aPTT prolongs as the activated protein C in the patient’s plasma inactivates factors V and VIII on the reagent plasma.
	pathology.mc.duke.edu /coag/TestDes.htm (9567 words)

	Medical Laboratory Services
		The aPTT test measures the length of time (in seconds) that it takes for clotting to occur when reagents are added to plasma (liquid portion of the blood) in a test tube.
		The aPTT and PT tests are also sometimes used as pre-surgical screens for bleeding tendencies, although numerous studies have shown that they are not useful for this purpose.
		If the aPTT is prolonged, and the cause is not due to heparin contamination or to other pre-analytical problems such as an insufficient or clotted blood sample, then the aPTT is followed by mixing studies to check for possible factor deficiencies or inhibitors.
	www.mlsstjames.com /pages/tests/aptt.htm (1415 words)

	aPTT: The Test (Site not responding. Last check: 2007-10-26)
		Along with the PT test (which evaluates the extrinsic and common pathways of the coagulation cascade), the aPTT is often used as a starting place when investigating the cause of a bleeding or thrombotic (blood clot) episode.
		If the aPTT is prolonged, and the cause is not due to heparin contamination or to other pre-analytical problems such as an insufficient or clotted blood sample, then the aPTT is followed by mixing studies to decide whether there is deficient Coagulation Factor(s) or a coagulation inhibitor is present.
		The aPTT may be requested, along with other tests such as a PT test, when a patient presents with unexplained bleeding or bruising, or a thromboembolism (blood clot).
	www.labtestsonline.org.uk /understanding/analytes/aptt/test.html (1308 words)

	Coagulation instrument for performing clotting tests - Patent 4497774
		If an APTT test is to be done on a plasma sample, the sample is put in a cuvette that is coded in a way to program the instrument for an APTT test.
		The PT and APTT (both determined by the formation of a clot and differing because different reagents are used for the two tests) are within the index time of the instrument, so a test will be completed and the results recorded before the turntable is indexed to advance the cuvettes loaded in the instrument.
		The circuitry, of which photocells 64 and 66 are a part, determine the PT and APTT of the plasma in the receptacles 117 and 118, respectively, because of the reagents added to the plasma samples.
	www.freepatentsonline.com /4497774.html (4814 words)

	HEPARIN THERAPY
		However, some patients receiving heparin but not demonstrating an adequate aPTT prolongation may require further laboratory evaluation for heparin resistance.
		Using linear-regression, a graph is prepared that correlates the aPTT in seconds to the heparin Anti-Xa units.
		Whenever the heparin dosage is changed, the aPTT should be reevaluated every 6 hours until the desired therapeutic range is reached.
	www.utmb.edu /lsg/LabSurvivalGuide/hem/HEPARIN_THERAPY.htm (504 words)

	CAP - Addressing clinical etiologies of a prolonged aPTT
		It is important to evaluate a new reagent or an instrument used to perform the aPTT in order to determine the effectiveness of the method in identifying the aforementioned etiologies.
		The normal plasma used for mixing with the patient's plasma should have a known concentration of coagulation factors, particularly factors V and VIII (near 100 percent), and should be a fresh-frozen and platelet-depleted specimen.
		If the resulting aPTT fails to correct to the reference range, an inhibitor likely is present and evaluation of the type (cause) of the inhibitor is indicated.
	www.cap.org /apps/cap.portal?_nfpb=true&cntvwrPtlt_actionOverride=/portlets/contentViewer/show&_windowLabel=cntvwrPtlt&cntvwrPtlt{actionForm.contentReference}=cap_today/case_study/coag4.html&_state=maximized&_pageLabel=cntvwr (1867 words)

	Use of Anti-Xa Activity as a Marker for Heparin-Induced Bleeding in Patients with APTT >180 s -- Haliassos et al. 43 ...
		This prolongation of APTT was not heparin related, although
		The APTT assay (CTS Neothromtin; Behring) was performed in a semiautomated
		According to this method the patient's plasma (50 µL) is incubated with optimal amounts of phospholipids and an activator
	www.clinchem.org /cgi/content/full/43/9/1781 (1046 words)

	NW Newborn Drug Protocol - Heparin Pharmacology
		The normal APTT in term neonates and babies up to 30 days of age is 31-55 seconds.
		APTT is used to monitor unfractionated heparin treatment and is reagent/instrument specific.
		APTT monitoring is important to prevent overdose with the associated bleeding risk.
	www.adhb.govt.nz /newborn/DrugProtocols/HeparinPharmacology.htm (669 words)

	What is the APTT?
		It would be accurate to say that APTT is unique in that it clearly recognises the specific status of part-time workers in education, and especially their very specialised needs (which are best supported by the part-timers themselves).
		APTT also positively promotes the enormous contribution that part-timers bring to adult education, and wants to value part-time work as a career choice in its own right.
		All APTT members are entitled to attend full the APTT Council meetings which occur three times a year (one of which is the AGM).
	www.apttuk.com /apttinfo.htm (990 words)

	Activated Partial Thromboplastin Time (APTT), Testing at Millenova Immunology Laboratories (Site not responding. Last check: 2007-10-26)
		APTT is also sensitive to decreased concentrations of Fleicher and Fitzgerald Factors I, II, V, VIII, IX, X, XI and XII.
		In the APTT test a contact activator is used to stimulate the production of Factor XIIa by providing a surface for the function of high molecular weight kininogen, kallikrein and Factor XIIa.
		APTT is measured by the IL TestTM APTT-SP(liquid).
	millenova.com /tests/aptt.asp (345 words)

	Diagnostic Handbook (Site not responding. Last check: 2007-10-26)
		The APTT is a basic test used to detect abnormalities of coagulation involving the intrinsic pathway.
		Marked prolongation of the APTT (>80 secs) is usually due to haemophilia if the patient presents with bleeding, or due to Factor XII deficiency if the patient is asymptomatic.
		The APTT is used to monitor standard or unfractionated heparin but not low molecular weight heparin (LMWH) therapy.
	www.dml.co.nz /hbook/5a63ef8.htm (165 words)

	Coagulation Manual Online
		Factors VIII, IX, XI, and XII are assayed by performing the aPTT on dilutions of patient plasma mixed with an equal volume of substrate plasma that is prepared by the manufacturer to be deficient specifically in the clotting factor of interest.
		At PCMH we have a calibrated quantitative assay for FDP on the Dupont ACA.
		Both the PT and the aPTT are affected, but it is widely held that prolongation of the PT is the better monitor for titrating the dose of drug for best effect, due to its sensitivity to Factor VII.
	www.pathology.ecu.edu /coagman.htm (8413 words)

	APPROACH TO A BLEEDING CHILD PEDIATRIC OCNALL (Site not responding. Last check: 2007-10-26)
		Prolongation of the PT or aPTT is indicative of a factor deficiency.
		An abnormal PT or aPTT should be followed by a mixing study, the results of which will indicate either the presence of an inhibitor or a factor deficiency.
		When aPTT mixing studies indicate a factor deficiency, it is necessary to measure factors VIII, IX and XI because deficiencies of these factors are associated with clinical bleeding.
	www.pediatriconcall.com /fordoctor/diseasesandcondition/ApproachBleedingChild.asp (3272 words)

	Heparin dosing review
		The recommended therapeutic range for the treatment of venous thrombosis is based on studies which demonstrated that thrombus extension is prevented by a heparin dose that prolonged the aPTT ratio to 1.5 to 2.5, corresponding to a heparin level of 0.2 to 0.4 units/ml.
		The "control" value used to determine the ratio is poorly defined, it may be the mean value of the normal range for the aPTT, or the patient's baseline aPTT (the aPTT measured before any heparin).
		Since the aPTT response to changes in heparin infusion rates is not always linear the dosage adjustments should be made in small increments of 100-200 units/hr.
	www.rxkinetics.com /heparin.html (2060 words)

	Abstract
		The possibility to analyze the inhibitors protein C and anti-thrombin are limited to a smaller number of laboratories and are often available only during office hours, which may jeopardize the optimal use of coagulation inhibitor concentrates.
		Ninety-two patients were included; the length of the stay at the ICU and hospital, the survival time at leaving the ICU and hospital and after 30 and 180 days were recorded.
		Especially prolonged APTT and/or low protein C level indicate a sinister prognosis in the ICU patient.
	www.blackwellpublishing.com /isth2003/abstract.asp?id=8746 (386 words)

	aPTT Mixing Studies
		Unless the cause for the prolonged aPTT is known, as in the case of heparin therapy, mixing studies may be necessary to determine the etiology of the prolonged result.
		After incubation at 37°C, an aPTT result equivalent to that of the original mixture is indicative of a factor deficiency or heparin.
		If the result of the aPTT on the incubated mixture demonstrates further prolongation (with the control remaining equivalent to the original result), a specific factor inhibitor is indicated.
	www.labcorp.com /datasets/labcorp/html/chapter/mono/cf006700.htm (980 words)

	February 1996 - Heparin Monitoring
		Heparin treatment is usually monitored to maintain the ratio of the patient's APTT to the mean control APTT within a defined range of approximately 1.5 to 2.5, referred to as the therapeutic range.
		The therapeutic range for any given APTT reagent should therefore be established in the clinical laboratory to correspond to a heparin level of 0.2 to 0.4 U/mL by protamine titration.
		Monitoring of heparin is difficult by conventional methods when the baseline APTT is prolonged as seen in patients with lupus anticoagulants and deficiencies of factor XII (Hagemen factor), prekallikrein (Fletcher factor) and high molecular weight kininogen (Fitzgerald factor).
	www.itxm.org /Archive/tmu2-96.htm (1093 words)

	Abstract
		There are data suggesting that the activated partial thromboplastin time (aPTT) and anti-Xa activity that are used for monitoring UFH therapy in adults are not optimal in children.
		The aPTT (Haemoliance Thrombosil, Beckman Coulter assayed on a MLA 1400) and anti-Xa activity (Haemoliance Anti-Xa chromogenic kit, Beckman Coulter assayed on MLA 1400) results from routine coagulation monitoring were collected prospectively.
		The aPTT and anti-Xa levels do not correlate with UFH dose in children receiving therapeutic doses of UFH.
	www.blackwellpublishing.com /isth2003/abstract.asp?id=8228 (317 words)

	Hemostasis Reference Laboratory \| Activated Partial Thromboplastin Time (APTT) with Kaolin
		The APTT assesses the coagulation factors of the intrinsic pathway (factors XII, XI, IX, VIII, X, V, prothrombin, and fibrinogen).
		The APTT will be prolonged in the presence of a factor deficiency, factor inhibitor, heparin or lupus-like inhibitors.
		Shortening of the APTT can occur as a result of coagulation factor activation due to a traumatic venipuncture, inadequately processed sample, or disseminated intravascular coagulation (DIC).
	www.psbc.org /lab_hemostasis/test01.htm (113 words)

	A Critical Care Drug Update
		In general, therapy with lepirudin is monitored using the aPTT ratio (patient aPTT at a given time over an aPTT reference value, usually median of the laboratory normal range for aPTT).
		Any aPTT ratio out of the target range is to be confirmed at once before drawing conclusions with respect to dose modifications, unless there is a clinical need to react immediately.
		Formation of antihirudin antibodies was observed in approximately 40% of HIT patients treated with lepirudin and this may increase the anticoagulant effect of lepirudin possibly because of delayed renal elimination of active lepirudin-antihirudin complexes.
	www.continuingeducation.com /pharmacy/critical-care/anti-thromb.html (1162 words)

	Refludan (Lepirudin) clinical pharmacology - prescription drugs and medications at RxList (Site not responding. Last check: 2007-10-26)
		The pharmacodynamic effect of REFLUDAN on the proteolytic activity of thrombin was routinely assessed as an increase in aPTT.
		For patients undergoing additional thrombolysis, elevated aPTT ratios were already observed at low lepirudin plasma concentrations, and further response to increasing plasma concentrations was relatively flat.
		At plasma concentrations of 1500 ng/mL, aPTT ratios were nearly 3.0 for healthy volunteers, 2.3 for patients with heparin-induced thrombocytopenia, and 2.1for patients with deep venous thrombosis.
	www.rxlist.com /cgi/generic3/lepirudin_cp.htm (1462 words)

	Oncology Nursing Society.
		The aPTT of this plasma sample was abnormally prolonged, yet a sample taken after the line was flushed with 50 ml of normal saline yielded a normal aPTT.
		The findings of this study indicate that the results of PT, aPTT, and FBG tests performed on blood obtained from pediatric patients through heparinized TVADs that have the same or similar dead space, are maintained by similar flushing techniques, and where sampling includes the same discard volume are unreliable for clinical use.
		With regard to aPTT values, the ratings of the four clinicians indicated that more than a third of the TVAD values were beyond the normal clinical range, an outcome that probably would have prompted change in care or a retest.
	www.ons.org /publications/journals/ONF/Volume29/Issue3/290326.asp (4913 words)

	The multiple faces of the partial thromboplastin time APTT (Site not responding. Last check: 2007-10-26)
		In the historical sketch by G. White [1], the importance of the activated partial thromboplastin time (APTT) for research on coagulation and hemophilia is emphasized.
		In this brief comment, I reflect upon the role played by the APTT in the discovery of activated protein C (APC) resistance and on the importance of the method for the elucidation of the underlying molecular mechanisms of this condition.
		A contributing factor is that the APTT is dependent on the activity of both FVa and FVIIIa.
	www.journalth.com /showitem.php?table=Articolo&id=13206 (1084 words)

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