Radioimmunoassay of triiodothyronine and thyroxine in capillary blood.

A radioimmunoassay technique for the estimation of T3 and T4 levels in capillary blood is described and evaluated in comparison to a simultaneously drawn and equally analyzed sample from the cubital vein. A total number of 236 samples thus received from the capillary and the vein from euthyroid, hypo- and hyper-thyroid patients were collected. For both T3 and T4 a good correlation (r = 0.94) was obtained. The clinical implication would especially be for paediatric practice.