Sepsis Measurement of<unk>  can be used as a marker of severe sepsis caused by bacteria and generally grades well with the degree of sepsis, although levels of<unk>  in the blood are very low.<unk>  has the greatest sensitivity (90%) and specificity (91%) for differentiating patients with systemic inflammatory response syndrome (SIRS) from those with sepsis, when compared with IL-2, IL-6, IL-8, CRP and TNF-alpha. Evidence is emerging that<unk>  levels can reduce unnecessary antibiotic prescribing to people with lower respiratory tract infections. Currently,<unk>  assays are widely used in the clinical environment. A meta-analysis reported a sensitivity of 76% and specificity of 70% for bacteremia. A 2018 systematic review comparing<unk>  and C-reactive<unk> ein (CRP) found<unk>  to have a sensitivity of 80% and a specificity of 77% in identifying septic patients. In the study,<unk>  outperformed CRP in diagnostic accuracy of predicting sepsis. In a 2018 meta-analysis of randomized trials of over 4400 ICU patients with sepsis, researchers concluded that<unk>  led therapy resulted in lower mortality and lower antibiotic administration. Organ rejection Immune responses to both organ rejection and severe bacterial infection can lead to similar symptoms such as swelling and fever that can make initial diagnosis difficult. To differentiate between acute rejection of an organ transplant and bacterial infections, plasma<unk>  levels have been proposed as a potential diagnostic tool. Typically the levels of<unk>  in the blood remain below 0.5 ng/mL in cases of acute organ rejection, which has been stated previously to be well below the 1 μg/mL typically seen in bacterial infection. Respiratory illnesses Given<unk>  is a blood marker for bacterial infections, evidence shows that it is a useful tool in guiding the initiation and duration of antibiotics in patients with bacterial pneumonia and other acute respiratory infections. The use of<unk>  guided antibiotic therapy leads to lower mortality, less antibiotic usage, decreased side effects due to antibiotics and promotes good antibiotic stewardship. The value in these<unk> ocols are evident since a high<unk>  level correlates with increased mortality in critically ill pneumonia patients especially those with a low CURB-65 pneumonia risk factor score. In adults with acute respiratory infections, a 2017 systematic review found that<unk> -guided therapy reduced mortality, reduced antibiotic use (2.4 less days of antibiotics) and led to decreased adverse drug effects across a variety of clinical settings (ED, ICU, primary care clinic).<unk> -guided treatment limits antibiotic exposure with no increased mortality in patients with acute exacerbation of chronic obstructive pulmonary disease. Using<unk>  to guide<unk> ocol in acute asthma exacerbation led to reduction in prescriptions of antibiotics in primary care clinics, emergency departments and during hospital admission. This was apparent without an increase in ventilator days or risk of intubation. Be that acute asthma exacerbation is one condition that leads to overuse of antibiotics worldwide, researchers concluded that<unk>  could help curb over-prescribing. Cardiovascular disease<unk>  serves a marker to help differentiate acute respiratory illness such as infection from an acute cardiovascular concern. It also has value as a prognostic lab value in patients with atherosclerosis or coronary heart disease as its levels correlate with the severity of the illness. The European Society of Cardiology recently released a<unk> -guided algorithm for administering antibiotics in patients with dyspnea and suspected acute heart failure. The guidelines use a cut off point of .2 ng/mL and above as the point at which to give antibiotics. This coincides with a 2017 review of literature which concluded that<unk>  can help reduce antibiotic overuse in patients presenting with acute heart failure. In regards to mortality, a meta analysis of over 5000 patients with heart failure concluded that elevated<unk>  was reliable in predicting short term mortality. Meningitis Blood<unk>  levels can help confirm bacterial meningitis and. if negative, can effectively rule out bacterial meningitis. This was shown in a review of over 2000 patients in which<unk>  had a sensitivity of 86% and a specificity of 80% for cerebrospinal fluid<unk> . Blood<unk>  measurements proved superior to cerebrospinal fluid<unk>  with a sensitivity of 95% and a specificity of 97% as a marker for bacterial meningitis. In acute meningitis, serum<unk>  is useful as a biomarker for sepsis. It can also be of use in determining viral meningitis versus bacterial meningitis. These findings are the result of a 2018 literature review. This followed a 2015 meta analysis that showed that<unk>  had a sensitivity of 90% and a specificity of 98% in judging viral versus bacterial meningitis.<unk>  also outperformed other biomarkers such as C-reactive<unk> ein. Gastrointestinal disease Evidence shows that an elevated<unk>  above .5 ng/mL could help diagnose infectious complications of inflammatory bowel disease such as abdominal abscesses, bacterial enterocolitis etc.<unk>  can be effective in early recognition of infections in IBD patients and decisions on whether to prescribe antibiotics. Kidney disease Patients with chronic kidney disease and end-stage renal disease are at higher risk for infections, and<unk>  has been studied in these populations, who often have higher levels.<unk>  can be dialyzed, and so levels are dependent upon when patients receive hemodialysis. While there is no formally accepted cutoff value for patients undergoing HD, using a value of greater or equal to 0.5 ng/mL yielded a sensitivity of 97-98% and a specificity of 70-96%. Hepatitis<unk> , possibly together with CRP, is used to corroborate the MELD score. Septic arthritis<unk>  at a cutoff value of .5 ng/mL was effective at ruling in septic arthritis in an analysis of over 8000 patients across 10 prospective studies.<unk>  had a sensitivity of 54% and specificity of 95%. The study also concluded that<unk>  outperforms C-reactive<unk> ein in differentiating septic arthritis from non-septic arthritis. Cancer A 2016 literature review showed that<unk>  has good value in diagnosing infections in oncologic patients. Moreso, it is especially effective in diagnosing major life threatening episodes in cancer patient such as bacteremia and sepsis.<unk>  is reliable to monitor recurrence of medullary thyroid carcinoma. In detecting cancer recurrence,<unk>  had a sensitivity and specificity of 96% and 96% respectively. Pediatrics In a meta analysis of 17 studies,<unk>  had a sensitivity of 85% and a specificity of 54% in diagnosing sepsis in neonates and children. The<unk>  cut off used was between 2-2.5 ng/mL. In children presenting with fever without an apparent source, a<unk>  level of .5 ng/mL had a sensitivity of 82% and specificity of 86%. At a 5 ng/mL value, the sensitivity and specificity were 61% and 94%.<unk>  can help the clinical decision making while identifying invasive bacterial infection in children with unexplained fever.<unk>  levels correlate with the degree of illness in pediatric patients with sepsis or urinary tract infections making it effective as a prognostic lab value in these patients. Antibiotic stewardship<unk>  guided cessation of antibiotic use reduces duration of antibiotic exposure and lowers mortality in critically ill patients in the Intensive Care Unit. In adult emergency department patients with respiratory tract illnesses,<unk> -guided treatment groups had reduced antibiotic use.
Procalcitonin
Calcitonin
Thyroglobulin
Parathyroid hormone-related protein
Stanniocalcin
Mammaglobin
Parathyroid hormone
Adiponectin