An online conversion chart for most hormones can also be found here: http://www.questdiagnostics.com/dms/Documents/test-center/si_units.pdf
Of course an online conversion chart is handy, but most accept only one or two different units for input and produces only one output unit. What if your assay gives hormone levels in mg/ml, and you want to convert to pmol/l? What if I want to measure an analyte that is not on the chart (e.g. the gastric hormone ghrelin, or the fish calcium-regulating hormone stanniocalcin!)?
A good way to become independent of conversion charts from unknown sources and to get to grips with chemical calculations is to include not only numerical values but also the units in which they are expressed.
To expand on Neil Wang's correct answer: 10 µg/dL = (10^-6 g)/(10^-1 l) = 10^-5 g/l.
By dividing both "g" and "mol" by the factor 10^-9: M = 362.46 g/mol = (362.46·10^-9 g)/(10^-9 mol).
Looking at the units only you see that you have to divide (not multiply, a mistake quite often made!) "g/l" by "g/mol" to eliminate the unit "g" and to obtain the desired dimension of moles per liter: (10^-5 g/l)/{(362.46·10^-9 g)/(10^-9 mol)} = 27.59·10^-9 mol/l = 27.59 nmol/l.
Suppose an assay gives its results in mg/l, and you want to convert to µmol/l, the conversion becomes (10^-3 g/l)/{(362.46·10^-6 g)/(10^-6 mol)} = 2.76·10^-6 mol/l = 2.76 µmol/l.
Writing units maybe looks redundant, but it is the best way to derive conversion factors and to check the correctness of an answer.
(These fractions and exponents look much better if you write them out!)
