ABSTRACT
OBJECTIVE: Our goal was to determine the status of prenatal Down syndrome screening in the United States in 1995. STUDY DESIGN: Information was sought via questionnaire from laboratories participating in external proficiency testing. RESULTS: Services were provided to 2,498,000 women annually by 265 screening laboratories. All but 10 laboratories offered both open neural tube defect and Down syndrome screening. Twenty-one percent of Down syndrome interpretations were based on alpha-fetoprotein measurements alone; 79% also included other serum analytes. Sixty-six laboratories (26%) offered interpretations at 14 weeks' gestation or earlier. CONCLUSIONS: Some laboratories extend serum screening too early in gestation for optimal neural tube defect interpretation. When 1995 was compared with 1992, more women were being screened, a higher proportion were receiving a Down syndrome interpretation, and more interpretations were based on multiple analytes. Laboratories should be encouraged to use some combination of multiple markers when screening for Down syndrome.
Subject(s)
Chorionic Gonadotropin/blood , Down Syndrome/blood , Down Syndrome/diagnosis , Estriol/blood , Laboratories , Prenatal Diagnosis , alpha-Fetoproteins/analysis , Amniotic Fluid/chemistry , Female , Gestational Age , Humans , Mass Screening , Organizations, Nonprofit , Pregnancy , Surveys and Questionnaires , United StatesABSTRACT
Appropriate use of test strategies requires not only an appreciation of analytic considerations and the ability of the tests to confirm or exclude the hypotheses, but also an understanding of the underlying pathophysiology and clinical features of the problems to be addressed. This discussion covers disease definition, pathophysiology, analytic considerations, and strategies for diagnosis and management.
Subject(s)
Hyperglycemia/diagnosis , Hypoglycemia/diagnosis , Blood Glucose/analysis , C-Peptide/blood , Diabetes Mellitus/classification , Diabetes Mellitus/diagnosis , Female , Glucose Tolerance Test , Glycated Hemoglobin/analysis , Humans , Insulin/blood , Male , Pregnancy , Proinsulin/bloodABSTRACT
We observed factitious hypophosphatemia in a patient who was receiving large amounts of intravenous mannitol. Mannitol concentrations as low as 25 mmol/L inhibited phosphorus measurement by the Dupont aca endpoint method; a kinetic method was unaffected. The mechanism of the mannitol interference was binding to molybdate in the reaction, decreasing both the rate of color development and the endpoint measurement. We conclude that the molybdate concentration in the DuPont method is suboptimal for measuring phosphorus in specimens containing mannitol.
