Activated Partial Thromboplastin Time (aPTT) is a tested used to evaluate the intrinsic coagulation system. It aids the screen for congenital deficiencies of factors II, V, VIII, IX, X, XI and XII of the coagulation pathway. aPTT is also useful in the monitoring of heparin therapy. In addition, aPTT is used in the detection of Hemophilia A, Christmas disease, liver failure and Vitamin K deficiency. Furthermore, the test proveds screening for the presence of dysfibrinogenemia, disseminated intravascular coagulation, congenital deficiency of Fitzgerald factor and prekallikrein. aPTT is prolonged in the deficiency or inhition of any of the coagulation factors except factor VII. Coumadin therapy, heparin, aprotinin and lupus anticoagulants also have the same effect on aPTT. Prolonged aPTT is often evaluated with that of Prothrombin Time (PT) to assess coagulation system.
Coagulation Method
Coagulation Reaction Detection Method (Scattered Light Detection Method)
Irridates red light (660nm) onto a mixture of blood plasma and reagent and detects the change in turbidity (when fibrin clots are formed) as the change in scattered light. It measures the coagulation time.
Coagulation Point Detection Method (Percentage Detection Method)
Calculates the coagulation time as the time required to achieve the amount of scattered light that is set for the coagulation detection point, using the amount of scattered light that is present just after the start of detection as 0% and the amount of scattered light that is present at the completion of coagulation as 100%
Sunday, November 8, 2009
Urine FEME
Urine FEME, also known as Urine Formed Elements with Microscopic Examination, consists of mainly two components. One component involves using reagent strips on patient's urine sample, while the other component involves microscopic examination of the urine.
The reagent strips contains nine separate reagent areas that contain different chemicals for the determination of a particular analyate. It also contains a non-reactive reagent pad which is used to determine the colour of the urine specimen. The automated machine used in the clinical laboratory is called the Clinitek Atlas analyzer. The machines contains the reagent strips mentioned above, and would be able to test several components in a urine specimen. The 12 components to be tested are pH, colour of urine, clarity, protein, occult blood, leukocytes, nitrite, glucose, ketone, bilirubin, urobilinogen and specific gravity. When a patient's urine sample reacts with the reagent pad, there would be a colour change on the respective reagent pad. A manual test can be carried out a spearate manual test reagent strip. The results can be read using a colour chart supplied by the manufacturer which indicate the presence or absence of some analytes, pH of urine or the level of analytes present in the urine specimen. These results may provide information regarding the patient's kidney function, urinary tract infections, carbohydrate metabolism and liver function
Firstly, 5ml of a patient's urine sample is poured into a clear plastic tube and labelled with the patient's particulars and barcode label. The tuve is then loaded onto a tube rack and loaded onto the analyzer. The machine would take up a small volume of the urine specimen and aliquot it onto the 10 reagent pads on the reagent strips. After which, the machine would detect the colour change on the test strip and the test results would be recorded.
The test results might give us some information of a patient's health status. For example, a presence of leukocytes could indicate a possible urinary tract infection. Presence of ketones could indicate a possible carbohydrate metabolic disorder or due to fasting. Presence of casts or blood in the urine could indicate a possible loss of kidney function.
The microscopic examination of the urine specimen involves charging a small volume of urine to a Kova microscopic slide. The slide is then examined using a light microscope and observed for the presence of RBC, WBC, epithelial cells, casts or crystals present in the urine. The results of microscopic examination should be cross-referenced to the results from the reagent strips, such as the presence of RBCs and WBCs. The results of the two different components should tally.
The reagent strips contains nine separate reagent areas that contain different chemicals for the determination of a particular analyate. It also contains a non-reactive reagent pad which is used to determine the colour of the urine specimen. The automated machine used in the clinical laboratory is called the Clinitek Atlas analyzer. The machines contains the reagent strips mentioned above, and would be able to test several components in a urine specimen. The 12 components to be tested are pH, colour of urine, clarity, protein, occult blood, leukocytes, nitrite, glucose, ketone, bilirubin, urobilinogen and specific gravity. When a patient's urine sample reacts with the reagent pad, there would be a colour change on the respective reagent pad. A manual test can be carried out a spearate manual test reagent strip. The results can be read using a colour chart supplied by the manufacturer which indicate the presence or absence of some analytes, pH of urine or the level of analytes present in the urine specimen. These results may provide information regarding the patient's kidney function, urinary tract infections, carbohydrate metabolism and liver function
Firstly, 5ml of a patient's urine sample is poured into a clear plastic tube and labelled with the patient's particulars and barcode label. The tuve is then loaded onto a tube rack and loaded onto the analyzer. The machine would take up a small volume of the urine specimen and aliquot it onto the 10 reagent pads on the reagent strips. After which, the machine would detect the colour change on the test strip and the test results would be recorded.
The test results might give us some information of a patient's health status. For example, a presence of leukocytes could indicate a possible urinary tract infection. Presence of ketones could indicate a possible carbohydrate metabolic disorder or due to fasting. Presence of casts or blood in the urine could indicate a possible loss of kidney function.
The microscopic examination of the urine specimen involves charging a small volume of urine to a Kova microscopic slide. The slide is then examined using a light microscope and observed for the presence of RBC, WBC, epithelial cells, casts or crystals present in the urine. The results of microscopic examination should be cross-referenced to the results from the reagent strips, such as the presence of RBCs and WBCs. The results of the two different components should tally.
Saturday, November 7, 2009
Streptococcus pneumoniae Antigen Test
Hi everyone. This is Jeremy (0702919B) from TG01 posting. This post will be about a test kit used in the lab to detect Streptococcus pneumoniae. Any questions, please feel free to ask.
Streptococcus pneumoniae Antigen Test
The BinaxNOW® Streptococcus pneumoniae Test is a rapid, in vitro immunochromatographic assay. It detects S. pneumoniae antigen in the urine of patients with pneumonia and also in the cerebral spinal fluid (CSF) of patients with meningitis. Both pneumonia and bacterial meningitis pose many complications to patients, and are almost always fatal if left untreated. Thus, it is necessary for an early detection and appropriate treatment to be administered. The Streptococcus pneumoniae Antigen Test, used together with culture and other methods, can also aid in the diagnosis of both pneumococcal pneumonia and pneumococcal meningitis.
Principle
The test kit involves the use of anti-S. pneumoniae antibody and control antibody. Both antibodies are adsorbed onto a nitrocellulose membrane (the anti-S. pneumoniae antibody on the sample line, while control antibody on the control line). The antibodies are conjugated to visualizing particles that are dried onto an inert fibrous support.
The presence of pneumococcal antigen in the sample will reacts to bind anti-S. pneumoniae conjugated antibody. The resulting antigen-conjugate complexes are captured by immobilized anti-S. pneumoniae antibody, forming the Sample Line. Immobilized control antibody captures anti-species conjugate, forming the Control Line.
Results Interpretation
Positive results:
Two pink-to-purple coloured lines will be formed. This means that an antigen was detected. Specimens with low levels of antigen may give a faint sample line. Any visible line is positive.
Negative results:
Only one pink-to-purple coloured control line in the top half of the window is formed. Formation of only the control line means that detection part of the test was done correctly, however no S. pneumoniae antigen was detected.
Invalid results:
No lines are seen, or only the sample line is seen. An invalid test must be repeated.
*Read results after 15 minutes.
That is all for the test kit. Thank you for reading.
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