PRL and TSH-secreting pituitary adenoma: This article reviews the most common errors while interpreting endocrine tests' including the hook effect and falsely normal values of prolactin (PRL) mainly in macroprolactinomas, macroprolactinemia and falsely elevated PRL, macro thyrotropinoma and falsely elevated thyroid-stimulating hormone (TSH) levels, heterophile antibodies leading to a false hormone elevation, biotin interference with hormonal assays and cross-reactivity of steroidal hormones with immunoassays cases and a brief overview of the other conditions.