I am currently pregnant after multiple miscarriages. i tested my hcg at 5 weeks 3 days pregnant and it was 16,557. is this an indication of a possible chromosomal abnormality, such as down syndrome?

HCG level is not good test for diagnosing Down syndrome. Mother's blood can be tested as it contains small amounts of fetal DNA. For info: https://www.nichd.nih.gov/health/topics/down/conditioninfo/diagnosis#:~:text=Prenatal%20Diagnostic%20Testing%20for%20Down%20Syndrome%201%20Amniocentesis,Percutaneous%20%28pronounced%20pur-kyoo-TEY-nee-uhs%29%20umbilical%20blood%20sampling%20%28PUBS%29.%20