Central laboratory or point-of-care testing of blood to determine natriuretic peptide (either BNP or N-terminal proBNP) concentration has a clinically established role in the differential diagnosis of patients presenting with breathlessness; normal levels exclude a diagnosis of heart failure, a common cause of...

Potassium, the most frequently measured electrolyte in clinical practice is, in health, maintained at a blood serum concentration within the approximate reference range of 3.5 to 5.2 mmol/L. Physiological control of this potassium concentration depends crucially on the ability of the healthy kidney to regulate...

Blood glucose concentration is normally maintained within the approximate range of 3.5-8.5 mmol/L (63-153 mg/dL) largely by the synergistic opposing action of two pancreatic hormones: insulin and glucagon. Insulin secretion causes decrease in blood glucose concentration and glucagon secretion causes increase in blood...

Arterial blood gas analysis provides the means for assessment of two related physiological functions that are disturbed in a wide range of medical conditions.  The first is the facility of the lungs to simultaneously add inspired oxygen to blood and remove carbon dioxide from blood, prior to excretion in expired air...

Lactic acidosis, the most common kind of metabolic acidosis, is characterized by reduced blood pH (usually <7.25) in association with marked increase in blood lactate (usually >5.0 mmol/L). Lactic acidosis has many possible causes but two broad etiological classes have been defined: type A (hypoxic) lactic acidosis and ...

The concentration of sodium (Na) in blood serum/plasma is determined by ion-specific electrode (ISE) technology that measures the physiologically important activity of sodium ions present in the aqueous (water) phase of plasma.  Two methods are available: direct ISE and indirect ISE. Direct ISE, which is employed in...

Discussion of electrolyte disorders associated with diabetes is most usually confined to the abnormality of plasma/serum sodium and potassium concentrations that occur in the two acute, life-threatening, conditions of decompensated diabetes: diabetic ketoacidosis (DKA) and hyperosmolar non-ketotic coma (HNKC).   As a...

Glomerular filtration rate (GFR) is a parameter of prime clinical significance because it defines kidney function. All those with reduced kidney function, no matter what the cause, have reduced GFR, and GFR correlates well with disease severity. The most accurate assessment of GFR is thus valuable not only for early...

http://erj.ersjournals.com/content/early/2014/10/16/09031936.00039214.full.pdf+html. Accessed Oct 2014. Arterial blood gas (ABG) analysis is clinically useful because it allows assessment of two vital interrelated physiological functions: pulmonary gas exchange and maintenance of blood pH (acid-base homeostasis)....

Human chorionic gonadptrophin (HCG) is a hormone composed of two dissimilar sub-units (a and b) that is normally only produced in measurable quantities by synctiotrophoblastic (placental) cells during pregnancy. Pregnancy testing is based on measurement of the concentration HCG in urine or blood serum.    Blood levels ...