Regional Laboratory
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Fortunately, the use of antepartum, intrapartum and neonatal ZDV has reduced the risk of perinatal HIV transmission. Unfortunately, transmission still occurs. The diagnosis of HIV infection of the newborn is difficult. Antibody levels reflect maternal antibody and are only useful to confirm maternal infection. The mean time for loss of maternal antibody is 10 months. If a child is antibody positive at 12 months but has no other positive finding, the antibody could still be maternal in origin and a retest at 15-18 months would be reasonable. A PCR test done in the nursery will detect as positive only 40-50% of children eventually found to be HIV positive. If repeated at 4-6 weeks and again at 4-6 months and all 3 PCR’s are negative and T-helper cell level and immunoglobulin levels are normal, the infant has a >95% chance of remaining negative. T-helper cell level and immunoglobulin level can also be followed to assist in the diagnosis. Ultimately, the failure to develop antibody over time is the only definitive criteria for ruling out HIV infection.
Hereditary hemochromatosis is a common inherited autosomal recessive disorder of iron metabolism. Recent studies have indicated a higher prevalence of this disease than previously thought. In persons of European descent, 3 to 5 per 1000 are homozygotes and 1 in 10 to 1 in 15 are heterozygotes, making it among the most common inherited diseases in this population. It is likely that a major proportion of affected individuals are underdiagnosed.
The disease is characterized by increased absorption of dietary iron and progressive iron deposition in the parenchymal cells of the liver, heart and certain endocrine organs. This leads to clinical complications including cirrhosis, diabetes, cardiomyopathy, arthritis, and susceptibility to liver cancer. Early diagnosis and treatment by phlebotomy are essential to reduce morbidity and mortality.
The recommended approach to screening for hemochromatosis is measurement of transferrin saturation. If transferrin saturation is greater than 60%, serum ferritin is measured. If serum ferritin is elevated (usually to more than twice normal), liver biopsy is recommended to assess iron overload and determine whether liver fibrosis or cirrhosis is present, and therapeutic phlebotomy is initiated. If serum ferritin is normal, screening tests are repeated at 2 year intervals, although some recommend instituting phlebotomy at this point.
Until recently, laboratory confirmation of hemochromatosis was based on HLA typing, since it has been known for many years that the hemochromatosis gene is closely associated with HLA genes on the short arm of chromosome 6. In 1996, Feder et. al described a candidate gene for hemochromatosis which they named HLA-H. The predominant mutation involves a cysteine to tyrosine change at amino acid position 282 (C282Y) caused by a G®A change at nucleotide position 845. Their findings were immediately confirmed by other investigators. Most studies have reported that 90-100% of patients diagnosed with hemochromatosis are homozygous for the C282Y mutation.
Heterozygotes have higher mean transferrin saturation and serum ferritin values than normal subjects, but complications due to iron overload are extremely rare. A less frequent alteration in hemochromatosis is a histidine to aspartic acid change at position 63 (H63D), but its role in the disease process is still controversial.
Although Feder et. al. named the gene HLA-H, this designation had already been applied to a lesser known gene that is clearly not associated with hemochromatosis. Although not yet official, it is likely that the C282Y mutation will be assigned the name HFE, which was assigned to the hemochromatosis gene prior to knowledge of its structure.
Clinical indications for DNA analysis in the diagnosis of hereditary hemochromatosis include confirmation of a clinical diagnosis of the disease, and testing of asymptomatic individuals with elevated transferrin saturation or serum ferritin levels. Testing may also be considered in asymptomatic individuals who have a family history of the disease, provided that appropriate genetic counseling is available.
Eugenio M. Taboada, M.D. joins Children’s Mercy Hospital
In October, Dr. Eugenio M. Taboada joined the pathology staff at Children’s Mercy Hospital. Dr. Taboada received his medical degree at the Universidad Nacional Autonoma de Nicaragua and did his residency at Albert Einstein College of Medicine and The Children’s Hospital of Harvard Medical School. He completed a fellowship at Cardinal Glennon Children’s Hospital and became an Associate Pathologist. He is board certified in Anatomic Pathology, Neuropathology and Pediatric Pathology. He can be reached at Children’s Mercy Hospital at 234-3126 (Fax 234-3794).
Children’s Mercy South Opens
Children’s Mercy South at 5808 West 110th opened on October 6, 1997. This facility is dedicated to the care of children and is comprised of: a Specialty Center representing 16 pediatric specialty areas, a Pediatric Surgicenter and an After Hours Clinic. The Children’s Mercy South Laboratory on the second floor operates as a patient service center for the RLA. Its hours are 9AM - 11PM Monday - Friday; 6PM - 11PM on Saturday and 3PM - 11PM on Sunday. The late evening hours, with no appointment necessary should add a measure of convenience for our customers. The phlebotomist is especially trained to draw specimens from children. Sweat collection is available by appointment. Telephone: (913) 696-8210. Fax: 696-8266.
New Patient Service Center
On December 1, 1997, Children’s Mercy is opening a new location which will serve as an RLA Patient Service Center for specimen collection. Your patient are welcom at this new location which is:
Children’s Mercy Paseo Clinic 4605 Paseo Kansas City, MO 64110 Phone: 922-4012 Hours: 8AM - 5PM Mon - Fri