Approach to XXXX

@entity5838 @entity2741 @entity4613 @entity3736 @entity520 @entity460 @entity9495
@entity2741 can be defined as a serum @entity460 greater than 2 standard deviations above the normal mean in a reference laboratory. @entity460 in the blood is normally transported partly bound to plasma proteins (about 45%) notably albumin, partly bound to small anions such as @entity4613 and @entity3736 (about 10%) and partly in the free or ionized state (about 45%) (1). Although only the ionized @entity460 is metabolically active, ie. subject to transport into cells and capable of activating cellular processes, most laboratories report total serum @entity460 concentrations. Concentrations of total @entity460 in normal serum generally range between 8.5 and 10.6 mg/dL (2.12 to 2.65 mM) and levels above this are considered to be consistent with @entity2741 . Nevertheless, reference ranges may vary between laboratories.The normal range of ionized @entity460 is generally 4.65-5.30 mg/dL (1.16-1.31 mM), but again values may vary slightly between laboratories. When protein concentrations, and especially albumin concentrations, fluctuate substantially, total @entity460 levels may vary, whereas the ionized @entity460 may remain relatively stable. Thus dehydration or hemoconcentration during venipuncture may elevate serum albumin and a falsely elevated total serum @entity460 may be reported. Such elevations in total @entity460 , when albumin levels are increased, can be "corrected" by subtracting 0.8 mg/dL from the total @entity460 for every 1.0 g/dL by which the serum albumin concentration is >4 g/dL. Conversely when albumin levels are low, total @entity460 can be corrected by adding 0.8 mg/dL for every 1.0 g/dL by which the albumin is <4 g/dL. Thus, to correct for an abnormally high or low serum albumin the following formula can be used: Corrected @entity460 (mg/dL) = measured total serum @entity460 (mg/dL) + [4.0- serum albumin (g/dL) X 0.8] or Corrected @entity460 (mM) = measured total @entity9495 (mM) + [40 - serum albumin (g/L)] X 0.02. Even in the presence of a normal serum albumin, changes in blood pH can alter the equilibrium constant of the albumin- @entity9495 complex, with @entity520 reducing the binding and @entity5838 enhancing it. Consequently when major shifts in serum protein or pH are present it is most prudent to directly measure the ionized @entity460 level in order to determine the presence of @entity2741 .
