Analyzer Information and Courses from MediaLab, Inc.

Measuring ApoB and ApoA1 can be performed using standard immunoassay techniques. Nephelometry is popular, as are ELISA-based methods that are performed on automated chemistry analyzer platforms. The power of the ApoB/ApoA1 ratio as a cardiovascular risk marker is getting widespread attention. An individual with seemingly normal LDL-C may in fact have high ApoB concentrations. When this individual has his or her ApoB/ApoA1 ratio calculated, the risk is evident. Studies have also shown that patients with metabolic syndrome and type-2 diabetes can also easily be identified with the ApoB/ApoA1 ratio, whereas these patients cannot always be identified by measuring LDL-C and HDL-C.In 2004, the global INTERHEART study of risk factors for acute myocardial infarction concluded that the ApoB/ApoA1 ratio was the most important risk factor in all geographic regions. The ApoB/ApoA1 ratio is easy to use because the risk is integrated into a single number that indicates the balance between atherogenic and antiatherogenic particles.There have been many studies concerning the predictive power of the ApoB/ApoA1 ratio. One study, which involved thousands of patients who were followed for an average of 10 years, showed that the ApoB/ApoA1 ratio was a strong predictor of stroke in addition to other cardiovascular events. Due to the evidence presented in studies like these, the National Academy of Clinical Biochemistry (NACB) has recommended that the ApoB/ApoA1 ratio be used as an alternative to the usual total cholesterol (TC)/HDL cholesterol ratio when determining lipoprotein-related risk for cardiovascular disease. Some believe that ApoB/ApoA1 testing will eventually replace traditional LDL-C and HDL-C measurements.

Serum iron (SI) is a measure of circulating iron bound to transferrin and is reflective of total body iron. SI is elevated in hereditary hemochromatosis (HH) and acute hepatitis. SI is decreased in iron deficiency anemia and chronic inflammation. SI concentrations exhibit diurnal variation, with the lowest values occurring around midnight. In addition, specimens collected from the same individual at the same time of the day may exhibit day to day variations as high as 40%. SI determinations are also affected by diet, menstrual cycle, pregnancy, ingestion of iron supplements, and oral contraceptive use. SI levels alone are considered insensitive indicators of HH. SI is typically measured on automated analyzers using spectrophotometric methods. Iron in the sample is released from transferrin with an acid reagent, reduced to the ferrous state, and reacted with a chromogen such as bathophenanthroline or ferrozine. The intensity of the color change is proportional to the iron concentration. Interference can arise from the use of a hemolyzed sample and contamination of reagents and water with iron. A typical reference interval for SI is 60 - 150 micrograms/dL. SI is usually ordered along with its companion test, the total iron binding capacity (TIBC), or with transferrin (Tf).(2)

Error prevention depends on vigilance. Without this watchfulness, human factors can override systems designed to prevent mistakes. For example, people can make mistakes when they operate computerized analyzers. Ignoring or overriding warning messages about abnormal operating conditions can lead to testing errors. Medical professionals should be vigilant and remain open to corrective input.

The setting is automated chemistry department, night shift, busy core laboratory for a hospital based outreach laboratory. A medical technologist who operates the automated chemistry analyzer on third shift encounters short samples a couple of times a night. When this happens, he runs as many of the ordered tests as he can and fills in the blank results with a comment indicating that a short sample occurred. As far as he knows there isn't a policy that addresses this problem directly.The test reports out with the results and the comments. The technologist does not have to change the physician order in any way and is providing the maximum results that can be reported for the specimen in a timely fashion. This is done as a matter of patient care and quality service. There has not ever been a complaint about this practice as far as he knows. Are there any additional steps this technologist should be taking?Correct Answer: The technologist should follow the procedures that the laboratory has in place for testing and billing samples for which there is no order or for ambiguous orders. If the policies do not seem to address his particular situation, he thinks there should be a separate policy to cover this situation or has a question about it, he should talk to his supervisor or to the laboratory compliance officerDiscussion: This choice addresses the problem in the most complete manner, in that the employee fulfills his responsibility to take action when he thinks there is a problem.

Controls must resemble as closely as possible the human samples they emulate.For hematology analyzers, controls need to have the same consistency and color as human blood. Likewise, serum controls need to have similar amounts of chemicals to those found in human serum.

Illustrated in this field is a normoblast and a myelocyte, representing leukoerythroblastosis, a term associated with the release of immature cells from a disrupted marrow. Metastatic disease in the bone marrow, particularly in patients with primary breast or prostate cancer, is usually the culprit. Leukoerythroblastosis in the absence of anemia or thrombocytopenia is a signal to search for cancer metastic to the marrow. Nucleated RBCs were not identified on the blood smear seen here but were detected by an automated analyzer.The mortality rate of elderly patients with increased NRBCs, especially following accidents or general surgery, is greater.

In addition to determining the percent motility, the laboratory must evaluate the quality of the movement. The process of rating motility may vary somewhat from one laboratory to another. Normal motile sperm should have strong forward progressive motion. Automated sperm analyzers commercially available and specifically designed to evaluate semen can add specific information about motility parameters. In addition to determining percent motility, they calculate the speed at which the sperm are swimming in microns/second.