Of the first 83 elements in the periodic table, 80 have isotopes considered to be stable. Technetium, promethium (atomic numbers 43 and 61, respectively) and all the elements with an atomic number over 82 only have isotopes that are known to decompose through radioactive decay.nly 13 of the 38 known-but-unstable elements (assuming the total number of elements is 118) have isotopes with a half-life of at least 100 years. Every known isotope of the remaining 25 elements is highly radioactive; these are used in academic research and sometimes in industry and medicine.
Cortisol Saliva Test. This test uses a saliva sample to measure a personâs Cortisol level. Saliva testing can provide just as accurate a measurement of adrenal hormones like Cortisol as a blood test can.
This test is performed to determine if dexamethasone, which is a steroid similar to cortisol, has an effect on cortisol levels. Typically, the client takes a low or high dose of dexamethasone by mouth, and blood is drawn the next morning to determine if cortisol is present.