moles = (mass in grams)/MW.
pmol = pg/MW, so pg = pmol x MW.
MW is about 21,000 daltons (unglycosylated), so 1 pmol/L = 21,000 pg/L =
So, multiply the number of pmol/L by 21 and you have pg/mL.
if pg = pmol x MW,
Why is this not: pg = pmol x 21000
pg = 21000pmol
pg/L = 21,000pmol/L = 21pmol/ml