Keywords: control survey, radioimmunoassay, immunoradiometric assay, adrenocorticotropic hormone, growth hormone, somatomedin C, follicle stimulating hormone, luteinizing hormone, prolactin, thyroid stimulating hormone, triiodothyronine, free triiodothyronine, thyroxine, free thyroxine, triiodothyronine uptake, thyroglobulin, thyroxine binding globulin, calcitonin, insulin, C-peptide, glucagon, gastrin, testosterone, free testosterone, estradiol, progesterone, 17α-hydroxyprogesterone, aldosterone, cortisol, dehydroepiandrosterone sulfate, renin, immunoglobulin E, digoxin, α-fetoprotein, carcinoembryonic antigen, tissue polypeptide antigen, CA125, CA19-9, CA15-3, prostatic acid phosphatase, prostate specific antigen, β₂-microglobulin, ferritin