Aldosterone measurement is used in the investigation of patients with arterial hypertension and cases of primary and secondary aldosteronism.
Urinary aldosterone levels are inversely correlated with urinary sodium excretion. In normal cases, there are decreased urinary aldosterone levels with adequate sodium retention.
Aldosterone is a mineralocorticoid secreted by the adrenal cortex. The release of aldosterone is mainly controlled by the renin-angiotensin-aldosterone system. The decrease in extracellular fluid results in a decrease in the blood flow through the kidneys, which in turn stimulates the production and secretion of renin from the kidneys. Renin acts on angiotensinogen to form angiotensin I, which in the presence of the angiotensin converting enzyme (ACE), is converted to angiotensin II. Angiotensin II stimulates the adrenal cortex and increases aldosterone production.
Aldosterone affects the distal renal tubules, causing an increase in sodium and chloride reabsorption and an increase in the excretion of potassium and hydrogen ions. The result of these actions is to increase water retention and increase extracellular fluid. The end result of aldosterone changes is the regulation of blood pressure.
Aldosterone levels are measured in both plasma and urine. This information helps diagnose the primary aldosteronism caused by adrenal cortex damage, and the secondary aldosteronism that may be due to angiotensin or ACTH over-stimulation of the adrenal cortex. Primary hyperaldosteronism can be responsible for up to 15% of cases of hypertension, especially in middle age.
What Do Pathological Values Mean?
- Increase: Adrenal cortical hyperplasia, aldosterone-producing adenomas, cirrhosis with ascites, congestive heart failure, bleeding, hyperkalemia, hyponatremia, hypovolemia, low-sodium diet, malignant hypertension, nephrosis, nephrotic syndrome, pregnancy, primary hyperaldosteronism (Conn syndrome), stress. Medications: corticotropin, diazoxide, diuretics, hydralazine hydrochloride, sodium nitroprusside, oral contraceptives, potassium.
- Decrease: Addison's disease, high sodium diet, hypernatraemia, hypokalaemia, salt loss syndrome, sepsis, pregnancy preeclampsia. Medications: cortisone, methyldopa, non-steroidal anti-inflammatory drugs, propranolol, steroids.
Laboratory test results are the most important parameter for the diagnosis and monitoring of all pathological conditions. 70%-80% of diagnostic decisions are based on laboratory tests. The correct interpretation of laboratory results allows a doctor to distinguish "healthy" from "diseased".
Laboratory test results should not be interpreted from the numerical result of a single analysis. Test results should be interpreted in relation to each individual case and family history, clinical findings, and the results of other laboratory tests and information. Your personal physician should explain the importance of your test results.
At Diagnostiki Athinon we answer any questions you may have about the test you perform in our laboratory and we contact your doctor to get the best possible medical care.