Items in AFP with MESH term: False Positive Reactions
Diagnosis of Lyme Disease - Article
ABSTRACT: The use of serologic testing and its value in the diagnosis of Lyme disease remain confusing and controversial for physicians, especially concerning persons who are at low risk for the disease. The approach to diagnosing Lyme disease varies depending on the probability of disease (based on endemicity and clinical findings) and the stage at which the disease may be. In patients from endemic areas, Lyme disease may be diagnosed on clinical grounds alone in the presence of erythema migrans. These patients do not require serologic testing, although it may be considered according to patient preference. When the pretest probability is moderate (e.g., in a patient from a highly or moderately endemic area who has advanced manifestations of Lyme disease), serologic testing should be performed with the complete two-step approach in which a positive or equivocal serology is followed by a more specific Western blot test. Samples drawn from patients within four weeks of disease onset are tested by Western blot technique for both immunoglobulin M and immunoglobulin G antibodies; samples drawn more than four weeks after disease onset are tested for immunoglobulin G only. Patients who show no objective signs of Lyme disease have a low probability of the disease, and serologic testing in this group should be kept to a minimum because of the high risk of false-positive results. When unexplained non-specific systemic symptoms such as myalgia, fatigue, and paresthesias have persisted for a long time in a person from an endemic area, serologic testing should be performed with the complete two-step approach described above.
Screening for Gestational Diabetes Mellitus - Putting Prevention into Practice
Screening for Hepatitis C in Adults - Putting Prevention into Practice
ABSTRACT: Family physicians treat an increasing number of children with metabolic disorders identified through newborn screening, and they are often the first line of defense in responding to an abnormal screening result. How the family physician chooses to interpret information from the screening and what he or she chooses to tell the family affects the parent-child relationship, as well as the infant's medical and developmental outcomes. Family physicians must, therefore, be familiar with the current state of expanded newborn screening to effectively communicate results and formulate interventions. They also must recognize signs of metabolic disorders that may not be detected by newborn screening or that may not be a part of newborn screening in their state. For every infant identified with a metabolic disorder, 12 to 60 additional infants will receive a false-positive screening result. One recommendation for communicating results to parents is to explain what the initial and follow-up findings mean, even if the diagnosis is not confirmed. For infants with true-positive results, long-term follow-up involves regular medical examinations, communication with a metabolic treatment center, and developmental and neuropsychological testing to detect possible associated disorders in time for early intervention. This article provides a description of metabolic disorders included in expanded newborn screening programs; a list of disorders screened for in each state; and resources for obtaining ACTion sheets (guidelines for responding to newborn screening results), fact sheets, and emergency and acute illness protocols.
ABSTRACT: Urine drug screening can enhance workplace safety, monitor medication compliance, and detect drug abuse. Ordering and interpreting these tests requires an understanding of testing modalities, detection times for specific drugs, and common explanations for false-positive and false-negative results. Employment screening, federal regulations, unusual patient behavior, and risk patterns may prompt urine drug screening. Compliance testing may be necessary for patients taking controlled substances. Standard immunoassay testing is fast, inexpensive, and the preferred initial test for urine drug screening. This method reliably detects morphine, codeine, and heroin; however, it often does not detect other opioids such as hydrocodone, oxycodone, methadone, fentanyl, buprenorphine, and tramadol. Unexpected positive test results should be confirmed with gas chromatography/mass spectrometry or high-performance liquid chromatography. A positive test result reflects use of the drug within the previous one to three days, although marijuana can be detected in the system for a longer period of time. Careful attention to urine collection methods can identify some attempts by patients to produce false-negative test results.
ABSTRACT: The diagnosis and treatment of syphilis can present difficult dilemmas. Serologic tests can be negative if they are performed at the stage when lesions are present, and the VDRL test can be negative in patients with late syphilis. Cerebrospinal fluid examination is not required in patients with primary or secondary disease and no neurologic signs or symptoms, but it may be warranted in patients with late latent syphilis or in whom the duration of infection is unknown. Patients with penicillin allergy can be treated with alternative regimens if they have primary or secondary syphilis. Penicillin is the only effective drug for neurosyphilis; oral desensitization should be accomplished before treatment of penicillin-allergic patients. Other dilemmas may be encountered in the treatment of patients who have concurrent human immunodeficiency virus infection.