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Aldosterone release causes sodium and water retention, which causes increased blood volume, and a subsequent increase in blood pressure, which is sensed by the baroreceptors. [39] To maintain normal homeostasis these receptors also detect low blood pressure or low blood volume, causing aldosterone to be released.
Aldosterone is increased by blood loss, pregnancy, and possibly by other circumstances such as physical exertion, endotoxin shock, and burns. Aldosterone feedback : [ citation needed ] Feedback by aldosterone concentration itself is of a non-morphological character (that is, other than changes in cell number or structure) and is relatively poor ...
In the adrenal cortex, angiotensin II acts to cause the release of aldosterone. Aldosterone acts on the tubules (e.g., the distal convoluted tubules and the cortical collecting ducts) in the kidneys, causing them to reabsorb more sodium and water from the urine. This increases blood volume and, therefore, increases blood pressure.
Hyperaldosteronism is a medical condition wherein too much aldosterone is produced. High aldosterone levels can lead to lowered levels of potassium in the blood (hypokalemia) and increased hydrogen ion excretion . Aldosterone is normally produced in the adrenal glands.
The cutoff normal individuals from those with primary hyperaldosteronism is significantly affected by the conditions of testing, such as posture and time of day. On average, an ARR cutoff of 23.6 ng/dL per ng/(mL·h), expressed in alternative units as 651 pmol/L per μg/(L·h), has been estimated to have a sensitivity of 97% and specificity of 94%. [2]
Screening is usually done by measuring the aldosterone-to-renin ratio in the blood (ARR) whilst off interfering medications and a serum potassium over 4, with further testing used to confirm positive results. [1] While low blood potassium is classically described in primary hyperaldosteronism, this is only present in about a quarter of people. [1]
The mineralocorticoid receptor (or MR, MLR, MCR), also known as the aldosterone receptor or nuclear receptor subfamily 3, group C, member 2, (NR3C2) is a protein that in humans is encoded by the NR3C2 gene that is located on chromosome 4q31.1-31.2. [5] MR is a receptor with equal affinity for mineralocorticoids and glucocorticoids.
This in turn results in an increase of blood pressure and blood volume. Aldosterone is produced in the zona glomerulosa of the cortex of the adrenal gland and its secretion is mediated principally by angiotensin II but also by adrenocorticotrophic hormone (ACTH) and local potassium levels.