Calcium in blood

P. Anker, E. Wieland, D. Ammann, R.E. Dohner, R. Asper, and W. Simon, Neutral carrier based ion-selective electrode for the determination of total calcium in blood-serum. Anal. Chem. 53, 1970-1974... 

Until recently, it was accepted that the fundamental limit of detection of these sensors was at micromolar levels of the target ion in an aqueous sample, and the main application has been the determination of ions like sodium, potassium and calcium in blood samples, where the... 

Assay of Sodium, Potassium, and Calcium in blood serum and water... 

ASSAY OF SODIUM, POTASSIUM AND CALCIUM IN BLOOD SERUM AND WATER... 

How would you assay sodium, potassium and calcium in blood serum and water Explain. 

In biomedical applications, the ranges of ion concentration are higher by several orders of magnitude. For instance, the abovementioned calcium probes for living cells cannot be used because the dissociation constant is so low that they would be saturated. Special attention is thus to be paid to the ionophore moiety to achieve proper selectivity and efficiency of binding. For instance, at present there is a need for a selective fluorescent probe for the determination of calcium in blood which could work in the millimolar range in aqueous solutions so that optodes with immobilized probes on the tip could be made for continuous monitoring calcium in blood vessels. 

Elliot, W. E. Volumetric determination of calcium in blood serum. J. Biol. 

In addition to automated analysers for general use, sophisticated single purpose instruments have been developed and marketed, chiefly for clinical analyses (for example Astra 4 and Astra 8 from Beckman for the determination of sodium and potassium in blood or Orion Space-Stat SS-20 or SS-30 for the determination of calcium in blood). 

TABLE 6 6. Evidence of intracellular calcium in blood elements of bipolar patients... 

The amount of calcium in blood samples may be determined by precipitating it... 

The role of calcium in blood coagulation and in protein C, an anticoagulant... 

The major location of calcium in the body is in the skeleton, which contains more than 90% of the body calcium as phosphate and carbonate. Bone resorption and formation keeps this calcium in dynamic equilibrium with ionized and complexed calcium in blood, cellular fluids and membranes. Homeostasis is mainly regulated by the parathyroid hormone and vitamin D which lead to increased blood calcium levels, and by a thyroid hormone, calcitonin, which controls the plasma calcium concentration J5 Increasing the concentration of calcitonin decreases the blood calcium level, hence injections of calcitonin are used to treat severe hyperalcaemia arising from hyperparathyroidism, vitamin D intoxication or the injection of too high a level of parathyroid extract. High levels of calcitonin also decrease resorption of calcium from bone. Hypocalcaemia stimulates parathyroid activity, leading to increased release of calcium from bone, reduction in urinary excretion of calcium and increased absorption of calcium from the intestine. Urinary excretion of phosphate is enhanced. 

Moore LJ, Machlan LA (1972) High accuracy determination of calcium in blood serum by isotope dilution mass spectrometry. Anal Chem 44 2291-2296... 

Other examples of the detection of biologically relevant targets under physiological conditions are represented by calcein-doped silica nanoparticles for the determination of calcium in blood serum63 and PEBBLEs that report redox processes.64-66... 

W8. Willis, J. B, The detennination of calcium in blood serum by atomic absorption spectroscopy. Nature 186, 249-250 (1960). 

Deficiency conditions Rickets, deficit of phosphorus and calcium in blood... 

Buckley BM, Russell LJ. The measurement of ionized calcium in blood plasma. Ann Clin Biochem 1988 25 447-65. 

Toffaletti J, Blosser N, Kirvan K. Effects of storage temperature and time before centrifugation on ionized calcium in blood collected in plain vacutainer tubes and silicone-separator (SST) tubes. Clin Chem 1984 30 553-6. 

High levels of calcium in blood plasma cause the release of calcitonin from the thyroid gland, which inhibits the reabsorption of calcium from bone by inhibiting osteoclasts. 

Extensive work has been done on modifications of citric acid metabolism, which appear especially interesting because of the interrelationship between citrate and calcium in blood and urine, and of the numerous factors which are known to affect the citrate level in normal subjects. 

Complexometric titrations in the clinical laboratory are limited to those substances that occur in fairly high concentrations since volumetric methods are generally not too sensitive. The most important complexometric titration is the determination of calcium in blood (see Ref. 8). Chelating agents such as. EDTA are used in the treatment of heavy-metal poisoning, for example, when children ingest chipped paint that contains lead. The calcium chelate (as Na2CaY) is administered to prevent complexation and removal of calcium in the bones. Heavy metals such as lead form more stable EDTA chelates than calcium does and will displace the calcium from the EDTA. The chelated lead is then excreted via the kidneys. 

The extracellular calcium-sensing receptor (CaR) is a detector for the concentration of extracellular calcium in blood and extracellular fluid. It is responsible for... 

B. Pharmacokinetics. Fluoride is a weak acid (pKa 3.4) that is passively absorbed from the stomach and small intestine. In an acidic environment more fluoride is present as HF, which is more rapidly absorbed. Fasting peak absorption occurs in 30-60 minutes. The volume of distribution is 0.5-0.7 Ukg. Fluoride Is not protein bound, but binds readily to magnesium and calcium in blood, tissues, and bone (most fluoride in the body is bound to bone). The elimination half-life is 2.4-4.3 hours and is prolonged in patients with renal failure. 

Calcium analysis via ion-selective electrode has now become an inexpensive and dependable method for determining the free, ionized form of this element in blood and sera. A substantial portion of this technology has been due to an electrode which analyzes ionic calcium in blood (500 /iL sample) in 3 minutes with a standard deviation of 2%. ... 

The earliest FIA applications of dialysis were focused on developing microdialysis units for in vivo measurements such as the determination of glucose using a biosensor connected to a microdialysis probe. Other in vivo and microdialysis processes have been developed to study the bovine serum albumin (BSA) binding of streptomycin sulfate using a luminometer detector to monitor calcium in blood and for flu-orimetric detection and to monitor calcium in blood through chemiluminometry. 

---