Product Name: Aldosterone
# of Samples: 1 x 96 Assays
Intended Use: Competitive immunoenzymatic colorimetric method for quantitative determination of Aldosterone in serum or plasma.
Introduction: Aldosterone is a steroid hormone produced by the adrenal cortex in the adrenal gland, is the most potent mineralocorticoid in humans, it regulate sodium and potassium balance in the blood.
Aldosterone secretion appears to be stimulated primarily through the renin-angiotensin system
Acting on mineralocorticoid receptors (MR) on principal cells in the collecting ducts of the kidneys, it increases the permeability of their apical (luminal) membrane to potassium and sodium and activates their basolateral Na+/K+ pumps, stimulating ATP hydrolysis, reabsorbing sodium (Na+) ions and water into the blood, and excreting potassium (K+) ions into the urine. Aldosterone regulate plasma bicarbonate (HCO3-) levels and its acid/base balance.
Aldosterone is responsible for the reabsorption of about 2% of filtered sodium in the kidneys.
Plasma aldosterone levels normally vary with body position (upright>supine) and salt intake. Overall plasma aldosterone levels show a circadian rhythm which is similar to but less marked than cortisol, with peak levels in the early morning; about 75% of the daily production is secreted between 04:00 am and 10:00 am each day. Age-related levels tend to decline from fetal through adult life.
Abnormally high plasma aldosterone concentrations can occur in adenomas, glucocorticoid-responsive hyperaldosteronism, idiopathic.
Abnormally low aldosterone secretion occurs in a number of conditions including salt-wasting forms of congenital adrenal hyperplasia, nephropathy, and renal tubular acidosis.
Principles of the assay: Microtiter strip wells are precoated with anti-Aldosterone antibodies (solid-phase). Aldosterone in the sample competes with Aldosterone-HRP conjugate for antibody binding. After incubation a bound/free separation is performed by solid-phase washing. The formed immune complex is visualized by adding Tetramethylbenzidine (TMB) substrate which gives a blue reaction product. The intensity of this product is inversely proportional to the amount of Aldosterone in the sample. Sulphuric acid is added to stop the reaction. This produces a yellow endpoint colour. Absorption at 450 nm is read using an ELISA microwell plate reader.
Storage and Stability: The reagents are stable up to the expiry date stated on the label when stored at 2...8 °C in the dark.
Limitations of the Test: Sample(s), which are contaminated microbiologically, should not be used in the assay. Highly lipemic or haemolysed specimen(s) should similarly not be used. It is important that the time of reaction in each well is held constant for reproducible results. Pipetting of samples should not extend beyond ten minutes to avoid assay drift. If more than one plate is used, it is recommended to repeat the dose response curve. Addition of the substrate solution initiates a kinetic reaction, which is terminated by the addition of the stop solution. Therefore, the addition of the substrate and the stopping solution should be added in the same sequence to eliminate any time deviation during reaction. Plate readers measure vertically. Do not touch the bottom of the wells. Failure to remove adhering solution adequately in the aspiration or decantation wash step(s) may result in poor replication and spurious results.
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