withdraw its blood and use radioimmunoassy technique with estradiol kit.

Thank dear Ali,

which equipments I need? For example: estradiol kit + ELISA reader + standard solution and ......? I investigated lactate, glucose and cholesterol. Is there any special difference between estradiol and other (for example lactate, glucose and cholesterol) parameters methods or it is the same of above parameters?

Regards,

Using either gamma counter of Elisa technique.You are able to perform with either of them.Ask more question if you need.

radioimmunoassay or ELISA technique? which one is more sensitive for investigation of 17beta estradiol?

I don't think you need to worry too much about sensitivity. RIAs are most often slightly more sensitive than ELISAs, but in this case, there's not a great difference. A RIA protocol I looked at (see links below) has a sensitivity of 4.8 pg/ml and an ELISA protocol 8.7 pg/ml.

The approach you take should rather be based on practicalities as Ali has already mentioned - do you have the equipment needed, and in the case of RIA work, do you have permits to work with radioisotopes.

Many labs switched from RIA to ELISA when these became available, just for the reason of not having to deal with the radioisotope work including permits, special labs and expensive waste disposal.

 Whichever methodology you use (there's also e.g. DELFIA and HPLC techniques to consider), just make sure that you validate your method correctly for this new species so that you know that you're getting correct measurements. Good luck!

http://www.ibl-international.com/media/catalog/product/M/G/MG12101_IFU_en_17beta-Estradiol_RIA_int.pdf

http://www.abcam.com/17-beta-estradiol-elisa-kit-ab108667.html

Dear Björn thanks.

I have done this kind of experiment on Brook trout. Sex steroid levels such 17 β-estradiol or testosterone can be measured in plasma using blood tests after collecting blood by caudal puncture (~1 ml).

For 17 β-estradiol was measured by radioimmunoassay kits: # 07¬-138102; ImmuChem ™ Double Antibody ICN Biomedicals, Inc. Costa Mesa, CA, USA. 

You should consider your collection moment, to avoid the biases with circadian hormones. In my case all samples were held between 9 am and 1 pm.