Keywords: control survey, radioimmunoassay, α-fetoprotein, aldosterone, β₂-microglobulin, carcinoembryonic antigen, cortisol, C-peptide, digoxin, elastase 1, ferritin, free thyroxin, follicle stimulating hormone, gastrin, growth hormone, glucagon, immunoglobulin E, insulin, luteinizing hormone, prostatic acid phosphatase, prolactin, parathyroid hormone, triiodothyronine, triiodothyronine uptake, thyroxine, thyroid stimulating hormone