In medicine and health-related fields, a<unk>  or<unk>  interval is the<unk>  or the interval of values that is deemed normal for a physiological measurement in healthy persons (for example, the amount of creatinine in the blood, or the partial pressure of oxygen). It is a basis for comparison for a physician or other health professional to interpret a set of test results for a particular patient. Some important<unk> s in medicine are<unk> s for blood tests and<unk> s for urine tests. The standard definition of a<unk>  (usually referred to if not otherwise specified) originates in what is most prevalent in a<unk>  group taken from the general (i.e. total) population. This is the general<unk> . However, there are also optimal health<unk> s<unk> s that appear to have the optimal health impact) and<unk> s for particular conditions or statuses (such as pregnancy<unk> s for hormone levels). Values within the<unk>  (WRR) are those within normal limits (WNL). The limits are called the upper<unk>  limit (URL) or upper limit of normal (ULN) and the lower<unk>  limit (LRL) or lower limit of normal (LLN). In health care–related publishing, style sheets sometimes prefer the word<unk>  over the word normal to prevent the nontechnical senses of normal from being conflated with the statistical sense. Values outside a<unk>  are not necessarily pathologic, and they are not necessarily abnormal in any sense other than statistically. Nonetheless, they are indicators of probable pathosis. Sometimes the underlying cause is obvious; in other cases, challenging differential diagnosis is required to determine what is wrong and thus how to treat it. A cutoff or threshold is a limit used for binary classification, mainly between normal versus pathological (or probably pathological). Establishment methods for cutoffs include using an upper or a lower limit of a<unk> .
Reference range
Cancer slope factor
Threshold limit value
Indicative limit value
Baseline 
Mortality rate
Absolute threshold
Prevalence