Beckwith-Wiedemann Syndrome Workup

Updated: Dec 05, 2016
  • Author: Sunil Kumar Sinha, MD; Chief Editor: Robert P Hoffman, MD  more...
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Workup

Laboratory Studies

The following studies may be indicated in patients with suspected Beckwith-Wiedemann syndrome (BWS):

  • Proper documentation of hypoglycemia (blood glucose < 60 mg/dL) requires proper sample collection and processing. Guidelines for the monitoring and treatment of hypoglycemia have been established. [8, 9]
    • Ideally, blood samples for glucose assessment should be processed immediately after collection. Cells in the blood sample continue to metabolize glucose, even at cold temperatures, leading to falsely low glucose values and falsely high lactate values. Collecting the blood in a sodium fluoride-lined tube (gray top tube) inhibits glycolysis, reducing the likelihood of falsely low values.
    • Measurements made with portable glucometers are useful for screening but not for diagnosis of hypoglycemia. Portable glucometers are widely available and relatively inexpensive, which are their primary advantages in the outpatient management of diabetes mellitus. These devices, however, were not designed for accuracy because distinguishing between blood glucose values of 200 and 220 mg/dL, for example, is less important than making the device convenient and affordable. When compared with central laboratory assays, these glucometers display as high as 20% inaccuracy at the lower ranges. For diagnostic purposes (during fasting studies and in other hospital settings), blood glucose should be measured in the central hospital laboratory, preferably by the well-established glucose oxidase method. Portable glucometers remain useful for monitoring blood sugar on an outpatient basis, but persistent low values should prompt consultation with the physician.
    • At the time of hypoglycemia, obtain plasma ketones (acetoacetate and b-hydroxybutyrate), plasma free fatty acid, serum insulin, and serum IGF levels (IGF-1 and IGF-2 by radioimmunoassay; large molecular weight forms of IGF-2 can be detected by Western ligand blot).
    • If intravenous or intramuscular administration of 1 mg glucagon at the time of hypoglycemia results in a rise of blood glucose of at least 30 mg/dL above baseline, the test is consistent with inappropriately conserved glycogen stores as observed in hyperinsulinism or panhypopituitarism.
  • Patients with Beckwith-Wiedemann syndrome should be screened for hypercalciuria. A single random, nonfasting urine sample obtained at each health maintenance visit is adequate for this purpose.
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Imaging Studies

Longitudinal abdominal ultrasonography has been suggested to screen for embryonal tumors, although it should be performed concomitantly with training parents to examine their child's abdomen. Most authorities recommend at least biannual abdominal ultrasonographic examinations; however, in 1983, Professor Wiedemann recommended that children with Beckwith-Wiedemann syndrome undergo renal sonography at 3-month intervals through the third year of life and at 6-month intervals thereafter. Recent reports of rapidly presenting Wilms tumors in patients with Beckwith-Wiedemann syndrome continue to support this traditional guideline.

Chest radiography may exclude rare neural crest tumors such as thoracic neuroblastoma.

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Procedures

Perform an inpatient fasting study to identify the cause of hypoglycemia. Acute insulin response testing (currently available only as research protocol at the Children's Hospital of Philadelphia) may be performed to differentiate from known forms of congenital hyperinsulinism.

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