Which lab tests are performed in the workup of Down syndrome?

Updated: May 18, 2020
  • Author: Gratias Tom Mundakel, MBBS, DCH; Chief Editor: Maria Descartes, MD  more...
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Laboratory studies that may be helpful include the following:

  • Complete blood count with differential

  • Bone marrow examination to rule out leukemia

  • Thyroid-stimulating hormone (TSH) and thyroxine (T4) to rule out hypothyroidism

  • Papanicolaou smears every 1-3 years in sexually active women

  • Cytogenetic studies (karyotyping) for diagnosis of trisomy 21

  • Interphase fluorescence in situ hybridization (FISH) for rapid diagnosis of trisomy 21

  • Assessment of mosaicism for trisomy 21 (lymphocyte preparations, buccal mucosa cellular preparations, FISH, scoring frequency of trisomic cells)

  • Immunoglobulin G

  • Maternal serum biochemical markers

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