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.
1 Blood/Serum. 2  A cortisol test is done to measure the level of the hormone cortisol in the blood, which may indicate problems with the adrenal glands or pituitary gland. 3  Ideally, perform the test around 8:00 a.m., and aim for the optimal range for adults of 10-15 mcg/dL.hen it comes to cortisol testing, here are the best options. 1  Blood/Serum. 2  A cortisol test is done to measure the level of the hormone cortisol in the blood, which may indicate problems with the adrenal glands or pituitary gland.