Immunochemical detection of human blood in feces

Combining methylated SDC2 test in stool DNA, fecal immunochemical test, and tumor markers improves early detection of colorectal neoplasms

Objective

To explore the value of testing methylated SDC2 (SDC2) in stool DNA combined with fecal immunochemical test (FIT) and serum tumor markers (TM) for the early detection of colorectal neoplasms.

Methods

A total of 533 patients, including 150 with CRC (67 with early-stage CRC), 23 with APL, 85 with non-advanced adenomas and general polyps, and 275 with benign lesions and healthy controls. SDC2 was detected by methylation-specific PCR, FIT (hemoglobin, Hb and transferrin, TF) was detected by immunoassay, and the relationships between SDC2, FIT, and clinicopathological features were analyzed. Pathological biopsy or colonoscopy were used as gold standards for diagnosis, and the diagnostic efficacy of SDC2 combined with FIT and TM in CRC and APL evaluated using receiver operating characteristic (ROC) curves.

Results

SDC2 positive rates in early-stage CRC and APL were 77.6% (38/49) and 41.2% (7/17), respectively, and combination of SDC2 with FIT increased the positive rates to 98.0% (48/49) and 82.4% (14/17). The positive rates of SDC2 combined with FIT assay in the APL and CRC groups at stages 0-IV were 82.4% (14/17), 85.7% (6/7), 100% (16/16), 100% (26/26), 97.4% (38/39), and 100% (22/22), respectively. Compared to the controls, both the CRC and APL groups showed significantly higher positive detection rates of fecal SDC2 and FIT (χ2 = 114.116, P < 0.0001 and χ2 = 85.409, P < 0.0001, respectively). Our results demonstrate a significant difference in the qualitative methods of SDC2 and FIT for the detection of colorectal neoplasms (McNemar test, P < 0.0001). ROC curve analysis revealed that the sensitivities of SDC2 and FIT, alone or in combination, for the detection of early CRC and APL were 69.9%, 86.3%, and 93.9%, respectively (all P<0.0001). When combined with CEA, the sensitivity increased to 97.3% (P<0.0001).

Conclusions

SDC2 facilitates colorectal neoplasms screening, and when combined with FIT, it enhances detection. Furthermore, the combination of SDC2 with FIT and CEA maximizes overall colorectal neoplasm detection.

A review of cardiac troponin I detection by surface enhanced Raman spectroscopy: Under the spotlight of point-of-care testing

Cardiac troponin I (cTnI) is a biomarker widely related to acute myocardial infarction (AMI), one of the leading causes of death around the world. Point-of-care testing (POCT) of cTnI not only demands a short turnaround time for its detection but the highest accuracy levels to set expeditious and adequate clinical decisions. The analytical technique Surface-enhanced Raman spectroscopy (SERS) possesses several properties that tailor to the POCT format, such as its flexibility to couple with rapid assay platforms like microfluidics and paper-based immunoassays. Here, we analyze the strategies used for the detection of cTnI by SERS considering POCT requirements. From the detection ranges reported in the reviewed literature, we suggest the diseases other than AMI that could be diagnosed with this technique. For this, a section with information about cardiac and non-cardiac diseases with cTnI release, including their release kinetics or cut-off values are presented. Likewise, POCT features, the use of SERS as a POCT technique, and the biochemistry of cTnI are discussed. The information provided in this review allowed the identification of strengths and lacks of the available SERS-based point-of-care tests for cTnI and the disclosing of requirements for future assays design.

Evaluation of the usefulness of the simultaneous assay of fecal hemoglobin (Hb) and transferrin (Tf) in colorectal cancer screening - for the establishment of the Hb and Tf two-step cutoff assay (HTTC assay)

Background One of the issues of fecal immunochemical test (FIT) is false-negativity caused by hemoglobin degradation by bacteria. We investigated the usefulness of the transferrin assay, which is stable toward bacteria. Methods The study included 1174 patients who visited our hospital and underwent colonoscopy for some symptoms or for cancer screening. We compared the hemoglobin-transferrin combination assay with the hemoglobin-alone assay using the Discrete Clinical Chemistry Analyzer NS-Plus and 1174 clinical samples. In the combination assay, two hemoglobin cutoff values (a) and (b) and one transferrin cutoff value (c) were set. Cases with values of (a) or more were defined as primary positive and values lower than (b) were defined as negative. Cases with values between (a) and (b) underwent the transferrin assay. Then, cases with values of (c) or higher were defined as secondary positive. All primary and secondary positive cases were defined as positive. Among the combination of cutoff values (a), (b) and (c), we identified Method A exhibiting high specificity and a positive predictive value (PPV), and Method B exhibiting the highest sensitivity. Results In Method A, the sensitivity of colorectal cancer detection increased from 67.3% to 68.2%, the specificity significantly (p = 0.0011) increased from 90.5% to 92.6%, and the PPV increased from 42.9% to 49.6% compared with the hemoglobin-alone assay. In Method B, the sensitivity increased significantly (p = 0.046) from 67.3% to 71.1% and the PPV increased from 42.9% to 44.8%. Conclusions This combination assay showed higher accuracy and effectiveness for colorectal cancer screening.

Fecal immunochemical test for hemoglobin in combination with fecal transferrin in colorectal cancer screening

Objective

Fecal transferrin has been suggested as a complementary or even superior marker for early detection of colorectal cancer (CRC) besides fecal hemoglobin. We aimed to evaluate both markers individually and in combination in a large cohort of participants of screening colonoscopy.

Methods

Precolonoscopy stool samples were obtained from participants of screening colonoscopy and frozen at -80℃ until blinded analysis, using a dual-quantitative fecal immunochemical test (FIT) for hemoglobin and transferrin. Sensitivity, specificity and area under the curve (AUC) were calculated for CRC and advanced adenoma (AA).

Results

A total of 1667 participants fulfilled our inclusion criteria. All individuals with advanced neoplasm (AN) (16 CRC, 200 AA) and 300 randomly selected participants without AN were included. Mean age was 63 years and 56% were male. The AUC for CRC and AA was 92% and 68%, respectively, for hemoglobin vs. 79% and 58%, respectively for transferrin. Combination of both markers yielded an AUC for CRC and AA of 92% and 68%, respectively.

Conclusion

FIT for hemoglobin shows better diagnostic performance than FIT for transferrin for the detection of ANs (both proximal and distal neoplasms), and a combination of both markers does not improve the diagnostic performance.

Evaluation of the analytical performance of the novel NS-Prime system and examination of temperature stability of fecal transferrin compared with fecal hemoglobin as biomarkers in a colon cancer screening program

OBJECTIVE

To examine the analytical aspects of fecal transferrin (Tf) and hemoglobin (Hb) measured on the NS-Prime analyzer for use in a colon cancer screening program.

DESIGNS AND METHODS

Method evaluation and temperature stability studies for fecal Tf and Hb were completed. A method comparison was carried out against the NS-Plus system using samples collected from 254 screening program participants. A further 200 samples were analyzed to help determine suitable reference limits for fecal Tf using these systems.

RESULTS

The assay for fecal Tf showed acceptable linearity, precision, and recovery, and showed minimal carryover with low potential for impact by the prozone effect. The 95th percentile for fecal Tf obtained for the reference population was 4.9 µg/g feces. The collection device sufficiently maintained fecal Tf and Hb stability for at least 7 days at room temperature, 4 °C, and -20 °C. Fecal Tf and Hb were most stable at 4 °C and -20 °C, but showed considerable loss (20-40%) of both proteins at 37 °C within the first 7 days. Mixing small amounts of blood into diluted fecal samples maintained at 37 °C for various time periods showed >50% loss of both proteins within 1 h of incubation.

CONCLUSIONS

The NS-Prime analyzer showed acceptable performance for fecal Tf and Hb. These studies suggest that use of both Tf and Hb together as biomarkers will result in higher positivity rates, but this may not be attributed to greater stability of Tf over Hb in human feces.

Colorectal cancer screening: Comparison of transferrin and immuno fecal occult blood test

AIM: To evaluate the sensitivity and specificity of transfesrrin dipstick test (Tf) in colorectal cancer (CRC) screening and precancerous lesions screening.

METHODS: Eight hundreds and sixty-one individuals at high-risk for CRC were recruited. Six hundreds and eleven subsequently received the three fecal occult blood tests and colonoscopy with biopsy performed as needed. Fecal samples were obtained on the day before colonoscopy. Tf, immuno fecal occult blood test (IFOBT) and guaiac fecal occult blood test (g-FOBT) were performed simultaneously on the same stool. To minimize false-negative cases, all subjects with negative samples were asked to provide an additional stool specimen for a second test even a third test. If the results were all negative after testing three repeated samples, the subject was considered a true negative. The performance characteristics of Tf for detecting CRC and precancerous lesions were examined and compared to those of IFOBT and the combination of Tf, IFOBT and g-FOBT.

RESULTS: A total of six hundreds and eleven subjects met the study criteria including 25 with CRC and 60 with precancerous lesions. Sensitivity for detecting CRC was 92% for Tf and 96% for IFOBT, specificities of Tf and IFOBT were both 72.0% (95% CI: 68.2%-75.5%; χ² = 0.4, P > 0.05); positive likelihood ratios of those were 3.3 (95% CI: 2.8-3.9) and 3.4 (95% CI: 2.9-4.0), respectively. In precancerous lesions, sensitivities for Tf and IFOBT were 50% and 58%, respectively (χ² = 0.8, P > 0.05); specificities of Tf and IFOBT were 71.5% (95% CI: 67.6%-75.1%) and 72.2% (95% CI: 68.4%-75.8%); positive likelihood ratios of those were 1.8 (95% CI: 1.3-2.3) and 2.1 (95% CI: 1.6-2.7), respectively; compared to IFOBT, g-FOBT+ Tf+ IFOBT had a significantly higher positive rate for precancerous lesions (83% vs 58%, respectively; χ² = 9.1, P < 0.05). In patients with CRC and precancerous lesions, the sensitivities of Tf and IFOBT were 62% and 69% (χ² = 0.9, P > 0.05); specificities of those were 74.5% (95% CI: 70.6%-78.1%) and 75.5% (95% CI: 71.6%-79.0%); positive likelihood ratios of those were 2.5 (95% CI: 2.0-3.1) and 2.8 (95% CI: 2.3-3.5). Compared to IFOBT alone, combining g-FOBT, IFOBT and Tf led to significantly increased sensitivity for detecting CRC and cancerous lesions (69% vs 88%, respectively; χ² = 9.0, P < 0.05).

CONCLUSION: Tf dipstick test might be used as an additional tool for CRC and precancerous lesions screening in a high-risk cohort.

[Controversial issues in colorectal screening in Hungary: conflict of clinical and public health viewpoints]

In Hungary, mortality rates from colorectal cancer are dramatically high, therefore the reduction by population screening as a public health measure is considered as one of the priorities of National Public Health Program. In the beginning, a human-specific immunological test was applied in the "model programs", as a screening tool, to detect the occult blood in the stool; compliance was 32% in average. However, the objectives of the model programs have not been achieved, because, among other reasons, a debate on the method of choice and the strategy to follow have divided the professional public opinion. In this study the debated issues are critically discussed, being convinced that, at present, population screening seems to be the most promising way to alleviate the burden of colorectal cancer.

Usefulness of fecal lactoferrin and hemoglobin in diagnosis of colorectal diseases

AIM: To evaluate prospectively usefulness of fecal lactoferrin (Lf) and fecal hemoglobin (Hb) in the diagnosis of colorectal diseases.

METHODS: Fecal Lf and Hb were measured using ELISA in 872 patients before they underwent colorectal endoscopy.

RESULTS: Lf was positive in 18 (50%) of 36 patients with colorectal cancer, 25 (15.9%) of 157 with colorectal polyps, 29 (46.8%) of 62 with ulcerative colitis, and 25 (62.5%) of 40 (62.5%) with Crohn’s disease. The Hb-positive rates were 50%, 12.1%, 41.9% and 32.5%, respectively. Of the 318 patients free of abnormalities by colorectal endoscopy, Lf was positive in 29 (9.1%) and Hb was positive in 15 (4.7%). Among patients with Crohn’s disease, the Lf-positive rate was significantly higher than the Hb-positive rate. If either high Lf or Hb levels were considered positive, the positive rates rose to 61.1%, 51.6%, and 67.5% in the colorectal cancer group, ulcerative colitis group, and Crohn’s disease group, respectively. If both high Lf and Hb levels were rated positive, the positive predictive values (PPV) were 21% for colorectal cancer, 33% for ulcerative colitis, and 17% for Crohn’s disease, and PPV of high Hb level alone was 18%, 25% and 13%, respectively.

CONCLUSION: Fecal Lf and Hb were found useful in the detection of colorectal diseases, and the combination of the two measurements appears to increase the sensitivity and efficacy of diagnosis.

Evaluation of the sensitivity and specificity of four laboratory tests for detection of occult blood in cockatiel (Nymphicus hollandicus) excrement

OBJECTIVE

To compare sensitivity and specificity of cytologic examination and 3 chromogen tests for detection of occult blood in cockatiel (Nymphicus hollandicus) excrement.

ANIMALS

20 adult cockatiels.

PROCEDURES

Pooled blood from birds was divided into whole blood and lysate aliquots. Excrement was mixed with each aliquot in vitro to yield 6 hemoglobin (Hb) concentrations (range, 0.375 to 12.0 mg of Hb/g of excrement). For the in vivo portion of the study, birds were serially gavaged with each aliquot separately at 5 doses of Hb (range, 2.5 to 40 mg/kg). Three chromogen tests and cytologic examination were used to test excrement samples for occult blood. Sensitivity, specificity, and observer agreement were calculated.

RESULTS

In vitro specificity ranged from 85%to 100% for the 3 chromogen tests and was 100% for cytologic examination. Sensitivity was 0% to 35% for cytologic examination and 100% for the 3 chromogen tests on samples containing >or= 1.5 mg of Hb/g of excrement. In vivo specificity was 100%, 90%, 65%, and 45% for cytologic examination and the 3 chromogen tests, respectively. Sensitivity was 0% to 5% for cytologic examination and >or= 75% for all 3 chromogen tests after birds received doses of Hb >or= 20 mg/kg. Observer agreement was lowest for cytologic examination.

CONCLUSIONS AND CLINICAL RELEVANCE

Chromogen tests were more useful than cytologic examination for detection of occult blood in cockatiel excrement. The best combination of sensitivity, specificity, and observer agreement was obtained by use of a chromogen test.

Experiences in providing a screening service for colorectal cancer from a pathology laboratory

AIM

To provide a colorectal cancer screening service for the general public, based on the detection of blood in faeces, that was effective, affordable and convenient.

METHODS

Kits for collecting faecal specimens were sold directly to the public and, after collecting three specimens, kits were transported to the laboratory for testing by an immunochemical procedure involving a positive cut-off value. Reports were sent to participants and their nominated doctors who were requested to provide information on participants testing positive.

RESULTS

Over a 10-year period, 35 139 kits were analysed and 5.63% were positive. After follow-up, 7.4% of positive testing participants were found to have colorectal cancer, 23.4% adenomas, 34.6% miscellaneous non-neoplastic pathology and in 25.0% no abnormality was found. Sixty-six per cent of cancers were early stage, Dukes stages A and B. There were 35 139 kits processed on 16 240 individuals, indicating that a number were repeat testing.

CONCLUSIONS

The screening service was able to detect a high yield of colorectal pathology, especially early stage neoplasia which is curable, and encouraged repeat testing. Education of doctors about how to investigate a positive test, and of participants about symptoms, have been important lessons arising from this screening service.

Early detection for colorectal cancer: new aspects in fecal occult blood screening

The authors report on promising diagnostic methods of occult intestinal bleeding and discusses the potential new strategy of early detection of colorectal carcinomas in respect to old and new diagnostic measures available. Because of the limited sensitivity and specificity of classical methods used for the demonstration of occult fecal blood, the authors recommend the introduction of new techniques and markers in screening practice. It is presumed that new discoveries in molecular biology will improve the accuracy of early colorectal cancer prevention. Their implementation into routine screening, however, will not take place in the near future. Until their realization, improved screening efficacy is expected from the use of more specific and sensitive blood tests.

Detection by ELISA of low transferrin levels in bronchoalveolar secretions of preterm infants

Transferrin levels in bronchoalveolar secretions (BAS) are very low compared to serum levels in humans. For the exact measurement of transferrin concentrations in BAS a very sensitive assay was developed as a double sandwich enzyme immunoassay using the combination of a polyclonal and a monoclonal antibody against human transferrin. The measurable range of the assay was 1.5 to 100 ng/ml of human transferrin. The lowest measurable value was 0.84 ng/ml and the sensitivity of the assay was 0.88 ng/ml. The coefficient of variation was 14.1% for 25 ng/ml (intra-assay) and 11-20% (inter-assay). The levels measured in 123 samples of BAS of preterm infants ranged between 0.03 and 8.93 (microgram/microgram secretory component (SC)). The determination of transferrin in BAS of preterm infants is helpful in determining oxidative damage, e.g. the availability of free iron, in the neonatal lung. The transferrin concentration in BAS of neonates who recovered from respiratory distress syndrome (RDS) in the first six days of life was 0.48 compared to 0.52 ((microgram/microgram SC), median range) for infants who developed chronic lung disease.

Significance of serum iron and ferritin in patients with colorectal adenomas

BACKGROUND

Colorectal adenomas are often detected on mass screening, although detection rates with fecal occult blood tests are low. The relationship between colorectal adenomas and the resulting blood loss was examined indirectly, using serum iron and ferritin levels.

METHODS

Serum iron and ferritin concentrations were measured in 184 men with colorectal adenomas (> or = 1 cm in 92; < 1 cm in 92) and in 92 healthy male controls. Values in the three groups were compared. In the patients with adenomas > or = 1 cm, serum iron and ferritin levels were compared on the basis of the site, number, histology, and degree of dysplasia of the adenoma.

RESULTS

The mean serum iron level was significantly lower in patients with adenomas > or = 1 cm than in controls (P < 0.05), although this level did not differ significantly between those with adenomas < 1 cm and controls. The mean serum ferritin level also was significantly lower in patients with adenomas > or = 1 cm than in those with adenomas < 1 cm and controls (P < 0.05, P < 0.01, respectively), although this level did not differ between those with adenomas < 1 cm and controls. There was no difference in mean serum iron or ferritin levels on the basis of the site, number, histology, or degree of dysplasia of the adenoma.

CONCLUSIONS

We conclude that decreased serum iron and ferritin levels are related only to adenoma size and that adenomas > or = 1 cm may bleed steadily, resulting in iron deficiency. However, low dietary intake of iron and fiber may be one of the causes of low serum iron and ferritin.

Monoclonal antibodies for exercise-induced fecal blood detection--comparison with Hemofec

The purpose of this investigation was to determine the incidence of fecal occult blood in marathoners using an immunochemical technique (OC-Hemodia). Five stool specimens (2 pre- and 3 postrace) were collected from 24 male runners (mean age 41.4 +/- 9.3 yrs) and analysed for fecal occult blood using the OC-Hemodia test. The results were also compared with a qualitative test (Hemofec) in 12 subjects who were randomly selected from the overall group of 24 runners. With the immunochemical technique, the results evidenced the presence of fecal occult blood in 8 subjects in the first postrace stool specimens. Four of these 8 subjects also tested positive in the second postrace sample, whereas in the third postrace sample only one of them tested positive. With the qualitative test, fecal blood was demonstrated in 10 runners in the first postrace sample. Eight of them tested positive in the second sample, whereas only 5 tested positive in the third sample. The immunochemical technique is recommended for fecal occult blood detection in marathoners.

Laboratory study on occult gastrointestinal bleedings: differential diagnostic method for the parallel study of intact and fragmented hemoglobin

The authors produced various degradation products of human hemoglobin. With the aid of immune sera raised against native hemoglobin and their fragments, we examined the antigenicity of the intact molecule and fragments as well as the specificity and reactivity of the immune sera used. Since conventional guaiac-type reactions make no distinction between the different hemoglobin molecules and the methods described in recent years' publications only with immune sera raised against native intact hemoglobin, the demonstration of occult fecal blood has not reached the desired rate of efficacy in clinical practice. The authors recommend the introduction of a simple differential diagnostic methods suitable for the parallel examination of intact and fragmented hemoglobin.

Double immunochemical screening test (hemoglobin and albumin) for the detection of occult intestinal bleeding

The authors have developed a combined electrophoretic-immunoprecipitation technique suitable for the simultaneous demonstration of two blood proteins, i.e., hemoglobin and albumin, in the feces. The analytical sensitivity of the method is 2 micrograms hemoglobin and albumin/ml. The technique is simple, inexpensive, and suitable for the reliable demonstration of occult intestinal bleeding for either inpatients or mass screening. This technique is an aid not only to the fact that bleeding can be detected, but to its intensity, as well. This new technique improves the diagnostic accuracy of early detection of carcinomas and polyps, presumably without raising significantly the number of "false-positive" reactions.