National Medical Laboratory

13/11/2017

06/11/2017

The Widal test, developed in 1896 and named after its inventor, Georges-Fernand Widal, is a presumptive serological test for enteric fever or undulant fever whereby bacteria causing typhoid and malaria fever are mixed with a serum containing specific antibodies obtained from an infected individual. In cases of Salmonella infection, it is a demonstration of the presence of O-soma false-positive result. Test results need to be interpreted carefully to account for any history of enteric fever, typhoid vaccination, and the general level of antibodies in the populations in endemic areas of the world. Typhidot is the other test used to ascertain the diagnosis of typhoid fever. As with all serological tests, the rise in antibody levels needed to do the diagnosis takes 7–14 days, which limits its applicability in early diagnosis. Other means of diagnosing Salmonella typhi (and paratyphi) include cultures of blood, urine and faeces. These organisms make H2S from thiosulfate and can be acknowledged easily on differential media such as bismuth sulfite agar.
typhidot-rapid-assy
typhidot-rapid-assy
2-mercaptoethanol is often added to the Widal test. This agent more easily denatures the IgM class of antibodies, so if a decrease in the titre is seen after using this agent, it means that the contribution of IgM has been removed leaving the IgG component. This differentiation of antibody classes is significant as it allows for the difference of a recent (IgM) from an old infection (IgG).
The Widal test is positive if TO antigen titre is more than 1:160 in an active infection, or if TH antigen titre is more than 1:160 in past infection or in immunized persons. A single Widal test is of little clinical relevance due to the high number of cross-reacting infections, including malaria. If no other tests (either bacteriologic culture or more specific serology) are available, a fourfold increase in the titer (e.g., from 1:40 to 1:640) in the course of the infection, or a conversion from an IgM reaction to an IgG reaction of at least the same titre, would be consistent with a typhoid infection.
A new serological test called the Tubex test is neither superior nor better performing than the Widal test. Therefore, Tubex test is not recommended for diagnosis of typhoid fever.

05/11/2017

ESR
The erythrocyte sedimentation rate (ESR) is a relatively simple, inexpensive, non-specific test that has been used for many years to help detect inflammation interrelated with conditions such as infections, cancers, and autoimmune diseases.ESR is said to be a non-specific test because an elevated result often indicates the existence of inflammation but does not tell the health practitioner accurately where the inflammation is in the body or what is causing it. An ESR can be affected by other conditions besides inflammation. For this reason, the ESR is typically used in conjunction with other tests, such as C-reactive protein.ESR is used to help diagnose certain specific inflammatory diseases, temporal arthritis, systemic vasculitis and polymyalgia rheumatica. A significantly elevated ESR is one of the main test results used to support the diagnosis. This test may also be used to check disease activity and response to therapy in both of the above diseases as well as some others, such as systemic lupus erythematosus (SLE).
When is it ordered?
An ESR may be ordered when a condition or disease is suspected of causing inflammation anywhere in the body. There are several inflammatory conditions that may be detected using this test. For example, it may be ordered when arthritis is suspected of causing inflammation and pain in the joints or when digestive symptoms are suspected to be caused by inflammatory bowel disease. A health practitioner may order an ESR when an individual has symptoms that suggest polymyalgia rheumatica, systemic vasculitis, or temporal arthritisESR may also be ordered at regular intervals to assist in monitoring the course of these diseases.
, such as headaches, neck or shoulder pain, pelvic pain, anemia, poor appetite, unexplained weight loss, and joint hardness. The
Before doing an extensive workup looking for disease, a health practitioner may want to repeat the ESR.
What does the test result mean?
The result of an ESR is reported as the millimeters of clear fluid (plasma) that is present at the top portion of the tube after one hour (mm/hr).
Reference Ranges
The reference ranges of ESR can be found on your laboratory report. They are typically found to the right of your results.
If you do not have your ESR test report, consult your healthcare provider or the laboratory that performed the test to obtain the reference range.Laboratory test results are not meaningful by themselves. Their meaning comes from comparison to reference ranges. Reference ranges are the values expected for a healthy person. They are sometimes called "normal" values. By compare your test results with reference values, you and your healthcare provider can see if any of your test results fall outside the range of expected values. Values that are outside expected ranges can provide clues to help identify possible conditions or diseases.
While accuracy of laboratory testing has significantly evolved over the past few decades, some lab-to-lab variability can occur due to differences in testing equipment, chemical reagents, and techniques. This is a reason why so few reference ranges are provided on this site. It is important to know that you must use the range supplied by the laboratory that performed your test to evaluate whether your results are "within normal limits."

For more information, please read the article Reference Ranges and What They Mean.

05/11/2017

erythrocyte sedimentation rate (ESR)

01/11/2017

blood group
A blood type (also called a blood group) is a classification of blood based on the presence and absence of antibodies and also based on the presence or absence of inherited antigenic substances on the surface of red blood cells (Erythrocytes). These antigens may be proteins, carbohydrates, glycoproteins, or glycolipids, depending on the blood group system. Some of these antigens are also present on the surface of other types of cells of various tissues. Several of these red blood cell surface antigens can stem from one allele (or an alternative version of a gene) and collectively form a blood group system. Blood types are inherited and represent contributions from both parents.

Blood group systems
A complete blood type would explain a full set of 30 substances on the surface of RBCs, and a those blood type is one of many possible combinations of blood-group antigens. From corner to corner the 35 blood groups, over 600 different blood-group antigens have been found. Almost always, an individual has the same blood group for life, but very rarely a person’s blood type changes through addition or suppression of an antigen in infection, malignancy, or autoimmune disease. Another more common cause in blood type change is a bone marrow transplant. Bone-marrow transplants are performed for many leukemias and lymphomas, among other diseases. If a person receives bone marrow from someone who is a different ABO type (e.g., a type A patient receives a type O bone marrow), the patient's blood type will in time convert to the donor's type.

Some blood types are linked with birthright of other diseases; for example, the Kell antigen is sometimes associated with McLeod syndrome. Certain blood types may affect disadvantage to infections, an example being the resistance to specific malaria species seen in individuals lacking the Duffy antigen. The Duffy antigen, presumably as a result of natural selection, is less common in ethnic groups from areas with a high incidence of malaria.

31/10/2017

Anemia is a decrease in the total amount of red blood cells (RBCs) or hemoglobin in the blood, or a lowered ability of the blood to carry oxygen. When anemia comes on slowly, the symptoms are often vague and may include feeling tired, weakness, shortness of breath or a poor ability to exercise. Anemia that comes on quickly often has greater symptoms, which may include confusion, feeling like one is going to pass out, loss of consciousness, or increased thirst. Anemia must be important before a person becomes noticeably pale. Additional signs may occur depending on the underlying cause.
The three main types of anemia are due to blood loss, decreased red blood cell production, and increased red blood cells go down. Causes of blood loss include trauma and gastrointestinal bleeding, among others. Causes of decreased production include iron deficiency, a lack of vitamin B12, Thalassemia, and a number of neoplasms of the bone marrow. Causes of increased breakdown include a number of genetic conditions such as sickle cell anemia, infections like malaria, and certain autoimmune diseases. It can also be classified based on the size of red blood cells and amount of hemoglobin in each cell. If the cells are small, it is microcytic anemia. If they are large, it is macrocytic anemia while if they are normal sized, it is normocytic anemia. Analysis in men is based on hemoglobin of less than 13 to 14 g/dL, while in women; it must be less than 12 to 13 g/dL. Further testing is then required to determine the cause.
Certain groups of individuals, such as pregnant women, benefit from the use of iron pills for prevention. Dietary supplementation, without determining the specific cause, is not recommended. The use of blood transfusions is typically based on a person's signs and symptoms. In those without symptoms, they are not recommended unless hemoglobin levels are less than 60 to 80 g/L (6 to 8 g/dL). These recommendations may also apply to some people with acute bleeding. Erythropoiesis-stimulating medications are only recommended in those with severe anemia.
Anemia is the most common blood disorder, disturbing about a third of the global population. Iron-deficiency anemia affects nearly 1 billion peoples. In 2013, anemia due to iron deficiency resulted in about 183,000 deaths – down from 213,000 deaths in 1990.It is more common in women than men, during pregnancy, and in children and the mature. Anemia increases costs of medical care and lowers a person's productivity through a decreased ability to work. The name is derived from Ancient.