post analysis

• Post-analytic review of laboratory results

  1. Analytic correctness check (using delta checks, linearity ranges, etc.)

  2. Clinical significance check for the patient (applying critical values, reference ranges, pretest and posttest probability, etc.)
• Flags


  Indicators of a problem with the specimen or the result
• Flags


  • Indicate a problem with the specimen (e.g., the presence of an interfering substance)
  • Indicate an issue with the result (e.g., numeric value outside the analytic range of the method, or the need for confirmation by an additional assay)
• Frequent causes of inadequate sample

  • High concentrations of interfering substances (lipids, hemoglobin, paraproteins, bilirubin)
• Flags for specimens that require additional analysis

  • Indicate the presence of qualitative abnormalities (e.g., atypical lymphocytes, platelet clumps, red cell fragments)
• Flags for problematic results

  • Indicate if the analyte falls above or below the linear range
• Delta checks


  Comparing a current laboratory result with results obtained on a previous specimen from the same patient
• Reference intervals


  The range of values into which 95% of non-diseased individuals will fall
• Critical values


  Laboratory results that may represent a life-threatening situation
• Sensitivity


  Probability of a positive result in a person with the disease (true-positive rate)
• Specificity


  Probability of a negative result in a person without disease (true-negative rate)
• Screening tests


  • Require high sensitivity so that no case is missed
• Confirmatory tests


  • Require high specificity to be certain of the diagnosis
• Likelihood ratio


  Ratio of the probability of a given test result in the disease state over the probability of the same result in the non-disease state
• Predictive value


  Probability of disease or no disease for a positive or negative result, respectively
• Bayes theorem


  Uses information about test characteristics (sensitivity and specificity) and disease prevalence (pretest probability) to obtain the posttest probability of disease given a positive test or no disease given a negative test
• Types of anemia


  • Iron deficiency
  • Anemia of chronic disease
  • Hemolytic anemia
  • Macrocytic/nutritionally deficient anemia
• An increased Red Cell Distribution Width (RDW) in the cell histogram correlates with a degree of anisocytosis
• Elevation of LAP score differentiates Leukemoid reaction vs Chronic Myelogenous leukemia
• Presence of spherocytes signifies the presence of Hemolytic anemia
• Presence of codocytes signifies the presence of Thalassemia
• Prolonged PT signifies the presence of Factor VII deficiency
• Prolonged APTT signifies the presence of Factors XII, XI, IX, VIII deficiency
• Prolonged PT and APTT signify the presence of Factors I, II, V, and X deficiency or the presence of lupus anticoagulant
• By examining the urinary sodium, potassium, and osmolarity, the causes of hyponatremia and hypernatremia can be readily determined
• Liver function tests can distinguish among six different diseases of the liver: hepatitis, cirrhosis, biliary disease, space-occupying lesions of the liver, passive congestion, and fulminant hepatic failure
• Renal Failure can be readily diagnosed by observing elevated blood urea nitrogen and creatinine; it is possible to pinpoint the site of renal failure– that is, glomerular or tubular–from the ratio of serum to urine osmolality
• Blood gas results allow determination of the cause of metabolic versus respiratory acidosis or alkalosis
• Elevation of cardiac troponin in serum, in the proper clinical context, is diagnostic of myocardial infarction
• Elevations of serum PROCALCITONIN indicate sepsis or blood infection
• Elevations of serum C-reactive protein (CRP) indicate inflammatory disease
• Elevations of serum amylase and lipase point to acute pancreatitis
• Serum levels of T4 (or, better, free T4) and thyroid-stimulating hormone (TSH) can be used to diagnose primary or secondary hypothyroidism or hyperthyroidism
• Elevation of serum glucose and absence of insulin point to Diabetes mellitus
• Serum levels of cortisol and adrenocorticotropic hormone (ACTH) can be used to diagnose primary or secondary hypoadrenalism or hyperadrenalism
• Elevations of eosinophils point to the presence of allergy and parasitic infections
• The presence of cysts/eggs/ova/larvae are diagnostic stages of parasites found in different specimens
• A positive culture along with corresponding biochemical tests provide a better diagnosis of bacterial, fungal and viral infection
• The presence of dysmorphic red blood cells in urine indicates glomerular hematuria/bleeding
• The presence of RTE cell (bubble cell) in urine indicates acute tubular necrosis