This week I am posted to routine section. The routine section is where the analysis of urine and other excretory products are done. Stool analysis is also part of the routine section; only that the actual analysis is carried out in the BSC class 2 (Biosafety Cabinet). During urine analysis, tests such as pregnancy test, urine formed elements and urine phase contrast (UPC).
I want to highlight on 2 main tests that is done in the routine section. The first test is the hCG test. HCG test is also known as the pregnancy test. hCG is a short term for Human Chronic Gonadotropin. hCG is a glycoprotein hormone which is produced by the blastocyst. A blastocyst is a thin-walled structure in the earlier development containing a cluster of cells from which the embryo arises. The concentration of hCG increases with age. It is normally below 5IU/ml in women of child-bearing age. After conception, the level of hCG rises rapidly, reaching up to 200 000IU/ml during the first trimester. Therefore, the concentration of hCG in urine and serum proves to be a great marker for pregnancy.
The Testpack Plus hCG Combo Plus is used to measure the concentration of hCG. This test uses both monoclonal and polyclonal antibodies to detect increased levels of hCG. The specificity of this test kit enables it to eliminate the cross-reactivity interference from other glycoprotein hormones present in the urine and serum.
http://www.1-medical-equipment.com/Vendors/ABBOTTDI/SYSTEMS_/images/testpack.jpg
When urine is loaded into the sample well of the test kit with the help of a transfer pipette, the urine is allowed to transfer through the membrane. When the urine is transferred through the membrane, it mobilises the anti-hCG monoclonal antibody-colloid. When hCG is present, it will form a complex with the antibody-colloid. This complex then travels through the membrane and binds with the immobilised anti-hCG polyclonal antibody and thus provides a visual indication of the presence of hCG.
The test should be read at 5 minutes. When hCG is present at levels of 25mIU/ml or greater, a plus sign (+) will be indicated in the result window. A minus sign (-) will be indicated whenever there is no sign of hCG.
However there are limitations to this test. A negative result will appear if the urine is too diluted. False positive and false negative are resulted in patients with abnormal kidney functions eg. renal failure. Patients with renal failure tend to produce excessive amount of hCG. Inaccurate results will occur if urine contains too many bacteria.
Now, another test is the blood Beta-ketone test. Blood Beta-ketone is carried out to detect elevated amounts of beta-ketone in the blood. This usually occurs in patients suffering from diabetes. By using a device called Medisense Optium Monitor, it can measure the amount of beta-ketone in the blood sample through a current mechanism. A drop of blood is placed on a piece of test strip that is provided.
http://www.nuh.nhs.uk/qmc/mesu/images/Medisense-Optium---bevel-si.jpg
The beta-ketone in the blood sample will react with on the test strip and thus produce a small electrical current. The size of the current depends on the amount of ketones in the blood sample. There are limitations to this test. Beta-ketone in the blood must be measured within 30 minutes after blood collection. The test strip is not designed for use with serum of plasma samples.
Siti Nurfatin
0605853A
20 comments:
Hi Fatin,
I have some questions for you,
1)Why must the stool analysis be performed in the BSC 2?
2)Why must the test be read at 5 minutes?
3)What are urine formed elements and urine phase contrast?
Thankz!
Han Yang
TG01
hey Fatin!
Whao I realised theres quite a few tests to test for diabetes! Theres glucose/ketone test strip, HbA1c etc...
Can i ask how beta-ketone is link with diabetes? Is it a screening test or confirmatory test?
Thanks!
Cheers,
Huimin =)
Hi Fatin,
Can you explain in more details how the Medisense Optium Monitor works?
You mention that beta-ketone in the blood sample will react with on the test strip and thus produce a small electrical current. But how and what exactly causes the electric current?
Xin Yi
TG02
hello..
for the beta-ketone test, why is serum of plasma is not ideal for the test?
and why must it be measured within 30 minutes after blood collection?
sutiana
hey han yang,
1) stool analysis is done in the BSC 2because firstly, dealing with stool is dirty and of course the smell may be overwhelming. thus, doing it in the BSC 2 will help to protect the person doing it. this is because the airflow is inwards and it prevents air-borne pathogens to come in contact with the person.
2) the test must be read 5 minutes as viewing of results in less than 5 min will result in false positive and if its read more than 5 min, it will result in false negative.
3) urine formed elements are the things u see under the microscope, such as red blood cells, white blood cells, casts, crystals (calcium oxalate), microoraganisms (blastoconidia) and epithelial cells. urine phase contrast is used to identity dysmorphic and isomorohic RBCs. Dysmorphic RBCs are characterised by an inrregular outer cell membrane. isomorphic RBCs are charaterised by uniform shape and size of RBCs. these RBCs are seen in many conditions such as renal calculi and acute cytitis.
Hi Fatin!
Just a quick question that I hope you could answer for me...
Why is it that the presence of bacteria will cause inaccurate results? Is it because somehow, they produce hCG too and cause a false positive result? or..they act on hCG and give a false negative result?
Many thanks
Quan Jun
TG02
Group 8
27 August 2008
hey huimin,
yup! there are various ways to test for diabetes. =) anyway, blood beta-ketone is linked with diabetes because excess glucose is excreted instead of being converted to glycogen in body. therefore fats are being broken down instead to produce ATP. this causes ketone to released in the process. it is a screening test btw. =)
hi fatin,
you mentioned about beta-ketone, is it the same as beta-hydroxybutyrate? if yes, why test for tis type of ketone instead of other types of ketones for diabetes? and lastly, can beta-ketones be detected in urine too? if yes, why use blood to test for beta-ketones instead of urine?
thanks.
Malerie
TG02
hey xin yi,
the medisense optium blood beta-ketone test strips measures beta-hydroxybutyrate (B-OHB). normally, levels of B-OHB are expected to be less than 0.6mmol/ml(square). B-OHB levels may increase if the person fasts, exercise vigorously or has diabetes Tthe test strips can read blood beta-ketone levels between 0-8.0mmol/ml(square). The temperature must be between 18-30 deg celsius.
The strips must only be used once. About the electric current, the betaketone in the blood sample reacts with a certain component called hydroxybutyrate dehydrogenase on the test strip. This will cause a small amount of electric current to be produced. I hope I answered ur questions! =)
hi! firstly, the electrode in the strip is not designed to measure serum. another reason is that this will help to decrease the turnover time of the beta-ketone test. in order for us to get serum from blood samples, we need to spin down the tubes first in order to separate the serum and red cells.so by using blood to do the test helps to save time. furthermore, beta-ketone in the blood will be repleted in a short time.this is due to the cell metabolism that is occurring in the blood. thats why the test has to be done in 30 min. hope this helps! =)
hey quan jun,
hmm, the microorganisms will act on the hCG to produce a false negative result. this may due to the fact that microorganisms that replete the amount of hCG in the blood. another reason may be that the presence of microorganisms interfere with the reading of hCG in the urine and thus false negative results will be resulted. hope this helps!
hey malerie,
as far as i know its not the same as beta-ketone. i believe the beta-hydroxybutyrate is a component in the strip that reacts with the beta-ketone to give the results. blood ketone is chosen over urine ketone as results tend to be more accurate in blood ketone.blood ketone gives the amount of ketone at the time the test is done. whereas for urine ketone,it can be hours behind as urine may be stored in the bladder for several hours. this may give an inaccurate result as the amount of ketone is not the exact amount at the time the test is done, hope this helps!
Hello!
Is the pregnancy test kit disposable? if it's not disposable, how do you ensure that there is no cross contamination between specimens?
Is it the same as those type of pregnancy test kit available in pharmacies? If no, what are the differences?
you also mention that there are possibility of false negative and false positive results. so are there any comfirmatory test performed?
Thanks
Yu Mei
TG01
hey yu mei,
sorry for the late reply. i have been busy.. btw, yes the pregnancy test kit is disposable. so we dont have to worry about cross-contamination. yes, it is similar to those sold in pharmacies. whenever we receive positive results, we redo the test to act as a confirmatry test. if the control dont work, we repeat the test using a new kit. hope this helps!
hey,
juz wondering, wads is the normal range for the blood ketone test??
sofie
A few clarification adn questions.
1. What causes the false negative result if it was read after 5 mins?
2. In diabetes, do we get to excrete excess glucose? If yes, then patients will not be hyperglycemic.
3. What is repleted? Is it depleted?
4. How does the presence of microorganisms affect the hCG levels?
5. How does urine ketone get to store in the bladder? This is the first time I ever know bladder can store components. I only know bladder is a temporary storage bag for urine before urination.
hey there sofie, then normal range for blood ketone is usually negative. it means when there is no ketone bodies in the body, we are normal. hope this helps!
hey ms chew,
1) evaporation line appears if the results are read after 5 minutes. this occurs when urine dries up,leaving a faint line. this is considered as insignificant. and thus the test has to be repeated.
2)yes. i found out that hyperglycemic is known as high conc of glucose in the blood.means that its not excreted right. ketones may also appear in urine without the presence of glucose in the body. this is due to the body breaking down fats for energy.
3) oops sorry. what i meant is used up. yes,it's like depleted.
4)im not too sure for this question.but what i know is the presence of microorganism wll interfere with the detection of hCG levels.they may block the hCG and prevent it from being detected or they may make use of hCG as nutrients for growth.
5)ketones are filtrated by the kidneys which is then excreted through urine.thus urine containing the ketones is stored temporarily in the bladder before being excreted.
Post a Comment