Guaiac
Immunochemistry
Gold Sodium Thiosulfate
Colorectal Neoplasms
Indicators and Reagents
Gastrointestinal bleeding and iron absorption in the experimental blind loop syndrome. (1/32)
Rats with surgically created self-filling jejunal blind loops and the blind loop syndrome manifested gastrointestinal bleeding and hyperabsorption of iron. Although the mean hematocrit and serum iron levels of rats with self-filling blind loops became overtly anemic and manifested low-serum iron levels. It is suggested that the documented gastrointestinal bleeding in these rats with the experimental blind loop syndrome is another manifestation of damage to the intestinal epithelium in conditions of small intestinal bacterial overgrowth. (+info)Effect of dietary factors on the detection of fecal occult blood in cats. (2/32)
Eight different diets were each fed to 6 cats to evaluate the effect on a guaiac and an o-tolidine fecal occult blood test. Fecal samples were collected from day 5 through day 7. Canine blood or pure cottage cheese were used as positive and negative controls, respectively. One hundred thirty-four fecal samples were analyzed. The dry fish (capelin) and vegetable (tapioca) diet and the pure cottage cheese diet had only negative results in both tests, whereas a canned chicken and cereal (rice) diet had negative results in all fecal samples in the o-tolidine tablet test and in 10 of 16 fecal samples in the guaiac paper test. All other fecal samples from cats eating 6 other diets and the canine blood additive were positive in both fecal occult blood tests. These results indicate that occult blood tests based on o-tolidine and guaiac are clinically useful, but cats need to be on a strict diet before the tests are used. (+info)Tests for occult in stools of children. (3/32)
Three tests for the presence of occult blood in the stools of children were examined; the orthotolidine test, the guaiacum resin test, and a modified reduced phenolphthalain test. The stools of 71 neonates, 33 normal children, and 8 children with suspected gastrointestinal pathology were examined. The 1% orthotolidine test and the guaiacum resin test produced a high number of false positive results in healthy children eating a meat-containing diet. It is concluded that a positive result by these tests is of little diagnostic value in children eating a normal diet. (+info)Guaiac and immunochemical tests for faecal occult blood in colorectal cancer screening. (4/32)
Seven hundred and eighty-six subjects spontaneously referring to our Center performed two guaiac (Rehydrated Hemoccult II (R.HO), and Hemoccult Sensa (HO S.)), and two immunochemical (OC Hemodia (Hdia) and Hemeselect (Hsel)) faecal occult blood tests on three consecutive faecal determinations. The positivity rates of 3 day R.HO, HO S., Hdia, and Hsel were 4.8%, 5.6%, 8.4% and 11.2% respectively. One hundred and thirty-five of the 150 subjects with at least one positive test completed the diagnostic work-up. Cancer was detected in three subjects and adenomas in 15. Three-day specificity estimates of R.HO, HO S., Hdia and Hsel in the overall series were 96.1%, 96.0%, 93.8% and 91.2% respectively, the differences between guaiac and immunochemical tests being significant. Corresponding values of specificity as determined on the first faecal sample only in the overall series were 98.1%, 98.3%, 96.1% and 94.9% respectively. No significant difference in specificity is evident when 3-day guaiac tests are compared to 1-day immunochemical ones. Three-day immunochemical testing is not recommended for screening purposes due to its very low specificity. Nevertheless, 1-day immunochemical testing is almost as specific as 3-day guaiac testing. A preliminary estimate of colonic neoplasms detection rates shows no difference as well. The benefit of 1-day testing on screening acceptability is evident, but the impact on sensitivity should be evaluated in a screening situation with a proper study design and a larger sample size. (+info)Comparative evaluation of a new bedside faecal occult blood test in a prospective multicentre study. (5/32)
BACKGROUND: Faecal occult blood testing is an established method of colorectal neoplasia screening. Guaiac-based tests are limited by poor patient compliance, low sensitivity, specificity and positive predictive value. Newer immunochemical-based tests, accurate but tedious, require a well-established laboratory set up. There is need for simpler immunochemical tests that can be performed at the out-patient clinic. AIM: To compare the performance characteristics of a new bedside immunological test strip device with a sensitive Guaiac-based and established immunochemical test for detection of faecal occult blood in patients undergoing colonoscopy. METHODS: A total of 389 consecutive patients from four centres who were referred for colonoscopy also provided the stool samples for detection of occult blood without dietary restrictions. Stool tests performed were (i) Guaiac-based, (ii) immunochemical enzyme-linked immunosorbent assay and (iii) bedside immunochemical strip test. RESULTS: At the optimal threshold level, the sensitivity and specificity of the beside immunochemical strip test for detection of significant colorectal neoplasia (adenomas >1.0 cm and carcinomas) were 60% and 95%, respectively. CONCLUSIONS: This bedside immunochemical strip test proved to be a simple, convenient, non-cumbersome and accurate tool with similar performance characteristics for detection of any bleeding lesion including colorectal neoplasia when compared with an established immunochemical faecal occult blood test. (+info)A quantitative immunochemical faecal occult blood test is more efficient for detecting significant colorectal neoplasia than a sensitive guaiac test. (6/32)
BACKGROUND: The sensitive guaiac faecal occult blood test, Haemoccult SENSA (HOS; Beckman Coulter, Fullerton, CA, USA), is our standard screening test for significant colorectal neoplasia. We evaluated an automatically-developed, quantified human haemoglobin immunochemical faecal test, OC-MICRO (Eiken Chemical Co., Tokyo, Japan), to improve test specificity and so reduce the colonoscopy burden. AIM: To compare guaiac faecal occult blood test and immunochemical faecal test diagnostic efficacy and costs for identifying significant neoplasia. METHODS: Colonoscopies were performed on patients who prepared three daily guaiac faecal occult blood tests with or without immunochemical faecal tests. RESULTS: Total colonoscopy was performed on 151 subjects who prepared both guaiac and immunochemical faecal tests (group 1) and the positive predictive values (PPV) were also compared to those of 162 subjects undergoing colonoscopy for positive guaiac faecal occult blood tests (group 2). In group 1, comparative sensitivity, specificity, and PPVs for significant neoplasia with guaiac faecal occult blood test were 75%, 34%, and 12% (PPV, 18% for group 2) and with immunochemical faecal test were 75%, 94% and 60% (P < 0.01 for specificity). The number of colonoscopy examinations needed to detect a significant neoplasm because of positive faecal occult blood tests was six to eight with HOS and two with OC-MICRO at 21-31% the cost of evaluating a positive guaiac faecal occult blood test. CONCLUSION: An immunochemical faecal test maintains the high sensitivity of guaiac faecal occult blood test, but significantly reduces the colonoscopy burden and screening costs. (+info)Comparison of a guaiac based and an immunochemical faecal occult blood test in screening for colorectal cancer in a general average risk population. (7/32)
BACKGROUND: The guaiac faecal occult blood test (G-FOBT) is recommended as a screening test for colorectal cancer but its low sensitivity has prevented its use throughout the world. METHODS: We compared the performances of the reference G-FOBT (non-rehydrated Hemoccult II test) and the immunochemical faecal occult blood test (I-FOBT) using different positivity cut-off values in an average risk population sample of 10,673 patients who completed the two tests. Patients with at least one test positive were asked to undergo colonoscopy. RESULTS: Using the usual cut-off point of 20 ng/ml haemoglobin, the gain in sensitivity associated with the use of I-FOBT (50% increase for cancer and 256% increase for high risk adenoma) was balanced by a decrease in specificity. The number of extra false positive results associated with the detection of one extra advanced neoplasia (cancer or high risk adenoma) was 2.17 (95% confidence interval 1.65-2.85). With a threshold of 50 ng/ml, I-FOBT detected more than twice as many advanced neoplasias as the G-FOBT (ratio of sensitivity = 2.33) without any loss in specificity (ratio of false positive rate = 0.99). With a threshold of 75 ng/ml, associated with a similar positivity rate to G-FOBT (2.4%), the use of I-FOBT allowed a gain in sensitivity of 90% and a decrease in the false positive rate of 33% for advanced neoplasia. CONCLUSIONS: Evidence in favour of the substitution of G-FOBT by I-FOBT is increasing, the gain being more important for high risk adenomas than for cancers. The automated reading technology allows choice of the positivity rate associated with an ideal balance between sensitivity and specificity. (+info)Comparison of a brush-sampling fecal immunochemical test for hemoglobin with a sensitive guaiac-based fecal occult blood test in detection of colorectal neoplasia. (8/32)
BACKGROUND: Fecal immunochemical tests (FIT) are an advanced fecal occult blood test (FOBT) technology that reduces barriers to population screening by simplifying the logistics of stool-sampling. The current study was conducted to undertake a paired comparison of a sensitive guaiac FOBT (GFOBT; Hemoccult II Sensa, Beckman Coulter, Fullerton, CA) with a brush-sampling FIT (InSure; Enterix, North Ryde, NSW, Australia), to determine whether this FIT improves detection of significant neoplasia. METHODS: Individuals sampled consecutive stools, at home, with both FIT and GFOBT sampling devices while following dietary restrictions appropriate for GFOBT. Study populations included a screening cohort (n = 2351) and a symptomatic diagnostic group (n = 161). Paired comparison of positivity rates was undertaken in those found to have cancer and/or significant adenoma (high-grade dysplasia, villous change, > or =10 mm, serrated histology or > or =3 polyps), benign pathology, or no pathology. RESULTS: Combined results for both cohorts showed that the FIT returned a true-positive result significantly more often in cancer (n = 24; 87.5% vs. 54.2%) and in significant adenomas (n = 61; 42.6% vs. 23.0%). Of all UICC Stage I cancers, the FIT was positive in 12 of 13 compared with 4 of 13 with the GFOBT (P = .002). In analyses of just the screening cohort, the FIT remained significantly better at detecting cancers and significant adenomas; the false-positive rate for any neoplasia was marginally higher with the FIT than the GFOBT (3.4% vs. 2.5%; 95% CI of difference, 0-1.8%), whereas positive predictive values were 41.9% and 40.4%, respectively. CONCLUSIONS: This brush-sampling FIT is more sensitive for cancers and significant adenomas than a sensitive GFOBT. As such, it should deliver greater reductions in colorectal cancer mortality and incidence than the GFOBT. (+info)Guaiac, also known as guaiacum, is not a medical term itself but it is related to a diagnostic test in medicine called the Guaiac test or guaiac card test. This test is used to detect the presence of occult blood (blood that is not visible to the naked eye) in stool, which may indicate conditions such as colorectal cancer, polyps, or inflammatory bowel disease.
The Guaiac test works by using a chemical reagent made from the wood of the guaiacum tree, which contains a compound called guaiaconic acid. When this reagent comes into contact with blood, it produces a blue-green color change. The stool sample is placed on a special card treated with the guaiac reagent and then a developer solution is added. If there is blood in the stool, the developer will cause the reagent to turn blue-green.
It's important to note that while a positive Guaiac test can indicate the presence of occult blood in the stool, it does not necessarily mean that there is cancer or other serious condition present. Other factors such as recent ingestion of iron supplements, red meat, or certain vegetables can also cause false-positive results. Therefore, a positive Guaiac test should be followed up with further diagnostic tests to confirm the diagnosis.
Occult blood refers to the presence of blood in the stool or gastrointestinal tract that is not visible to the naked eye. It is typically detected through chemical tests, such as fecal occult blood tests (FOBT) or fecal immunochemical tests (FIT), which can detect small amounts of blood in the stool. The presence of occult blood may indicate a variety of gastrointestinal conditions, including colorectal cancer, polyps, ulcers, inflammatory bowel disease, and other digestive disorders. It is important to follow up with medical evaluation if occult blood is detected, as early detection and treatment of underlying conditions can improve outcomes.
Immunochemistry is a branch of biochemistry and immunology that deals with the chemical basis of antigen-antibody interactions. It involves the application of chemical techniques and principles to the study of immune system components, particularly antibodies and antigens. Immunochemical methods are widely used in various fields such as clinical diagnostics, research, and forensic science for the detection, quantification, and characterization of different molecules, cells, and microorganisms. These methods include techniques like ELISA (Enzyme-Linked Immunosorbent Assay), Western blotting, immunoprecipitation, and immunohistochemistry.
Gold sodium thiosulfate is a medication that contains the active ingredients gold and sodium thiosulfate. It is used in the treatment of rheumatoid arthritis, a chronic autoimmune disease characterized by inflammation and damage to the joints. The gold component of the medication is thought to work by modulating the immune system and reducing inflammation, while the sodium thiosulfate helps to protect cells from the potential toxic effects of the gold.
Gold sodium thiosulfate is administered as an injection, typically on a weekly basis, and may be given in combination with other medications to manage rheumatoid arthritis. It is important to note that this medication can have serious side effects, including kidney damage, bone marrow suppression, and allergic reactions, and it should only be used under the close supervision of a healthcare professional.
A colonoscopy is a medical procedure used to examine the large intestine, also known as the colon and rectum. It is performed using a flexible tube with a tiny camera on the end, called a colonoscope, which is inserted into the rectum and gently guided through the entire length of the colon.
The procedure allows doctors to visually inspect the lining of the colon for any abnormalities such as polyps, ulcers, inflammation, or cancer. If any polyps are found during the procedure, they can be removed immediately using special tools passed through the colonoscope. Colonoscopy is an important tool in the prevention and early detection of colorectal cancer, which is one of the leading causes of cancer-related deaths worldwide.
Patients are usually given a sedative to help them relax during the procedure, which is typically performed on an outpatient basis in a hospital or clinic setting. The entire procedure usually takes about 30-60 minutes to complete, although patients should plan to spend several hours at the medical facility for preparation and recovery.
Colorectal neoplasms refer to abnormal growths in the colon or rectum, which can be benign or malignant. These growths can arise from the inner lining (mucosa) of the colon or rectum and can take various forms such as polyps, adenomas, or carcinomas.
Benign neoplasms, such as hyperplastic polyps and inflammatory polyps, are not cancerous but may need to be removed to prevent the development of malignant tumors. Adenomas, on the other hand, are precancerous lesions that can develop into colorectal cancer if left untreated.
Colorectal cancer is a malignant neoplasm that arises from the uncontrolled growth and division of cells in the colon or rectum. It is one of the most common types of cancer worldwide and can spread to other parts of the body through the bloodstream or lymphatic system.
Regular screening for colorectal neoplasms is recommended for individuals over the age of 50, as early detection and removal of precancerous lesions can significantly reduce the risk of developing colorectal cancer.
Indicators and reagents are terms commonly used in the field of clinical chemistry and laboratory medicine. Here are their definitions:
1. Indicator: An indicator is a substance that changes its color or other physical properties in response to a chemical change, such as a change in pH, oxidation-reduction potential, or the presence of a particular ion or molecule. Indicators are often used in laboratory tests to monitor or signal the progress of a reaction or to indicate the end point of a titration. A familiar example is the use of phenolphthalein as a pH indicator in acid-base titrations, which turns pink in basic solutions and colorless in acidic solutions.
2. Reagent: A reagent is a substance that is added to a system (such as a sample or a reaction mixture) to bring about a chemical reaction, test for the presence or absence of a particular component, or measure the concentration of a specific analyte. Reagents are typically chemicals with well-defined and consistent properties, allowing them to be used reliably in analytical procedures. Examples of reagents include enzymes, antibodies, dyes, metal ions, and organic compounds. In laboratory settings, reagents are often prepared and standardized according to strict protocols to ensure their quality and performance in diagnostic tests and research applications.
Medical mass screening, also known as population screening, is a public health service that aims to identify and detect asymptomatic individuals in a given population who have or are at risk of a specific disease. The goal is to provide early treatment, reduce morbidity and mortality, and prevent the spread of diseases within the community.
A mass screening program typically involves offering a simple, quick, and non-invasive test to a large number of people in a defined population, regardless of their risk factors or symptoms. Those who test positive are then referred for further diagnostic tests and appropriate medical interventions. Examples of mass screening programs include mammography for breast cancer detection, PSA (prostate-specific antigen) testing for prostate cancer, and fecal occult blood testing for colorectal cancer.
It is important to note that mass screening programs should be evidence-based, cost-effective, and ethically sound, with clear benefits outweighing potential harms. They should also consider factors such as the prevalence of the disease in the population, the accuracy and reliability of the screening test, and the availability and effectiveness of treatment options.