Mineralocorticoids  are the corticosteroids that act on the minerals (electrolytes), particularly sodium and potassium. Mineralocorticoids are:

  1. Aldosterone
  2. 11-deoxycorticosterone.


Mineralocorticoids are secreted by zona glomerulosa  of adrenal cortex.


Mineralocorticoids  are C21  steroids having  21 carbon atoms. Half-life of mineralocorticoids is 20 minutes.


Ninety percent of mineralocorticoid  activity is provided by aldosterone.

  1. On Sodium Ions

Aldosterone  acts on the distal convoluted  tubule and the collecting duct and increases the reabsorption  of sodium. During  hypersecretion of aldosterone,  the loss of  sodium through urine is  only few  milligram per  day. But during hyposecretion of aldosterone,  the loss of sodium through  urine increases  (hypernatriuria)  up to about 20g/day. It  proves the importance  of aldosterone in regulation  of sodium ion concentration and osmolality in the body.

  1.  On Extracellular Fluid Volume

When sodium  ions are reabsorbed  from the renal tubules, simultaneously water  is also reabsorbed. Water reabsorption  is almost equal  to sodium reabsorption;  so the net result is the increase in ECF volume. Even though aldosterone  increases the sodium reabsorption from  renal tubules, the  concentration of sodium  in the body does not increase  very much because water is also reabsorbed simultaneously. But still, there is a possibility  for mild increase  in concentration of  sodium in blood (mild hypernatremia). It induces  thirst, leading  to intake  of water  which  again increases the ECF volume and blood volume.

  1.  On Blood Pressure

Increase  in  ECF  volume  and  the  blood  volume  finally leads to increase in blood pressure. Aldosterone escape or escape phenomenon Aldosterone  escape  refers to escape  of the kidney from  salt-retaining effects  of excess administration or secretion of aldosterone,  as in the case of primary hyperaldosteronism.

  1.  On Potassium Ions

Aldosterone increases the  potassium excretion through the  renal  tubules.  When  aldosterone  is  deficient,  the potassium ion concentration in  ECF  increases leading to hyperkalemia. Hyperkalemia results  in  serious cardiac toxicity,  with weak contractions of  heart  and development of  arrhythmia. In  very severe conditions, it  may cause cardiac death. When aldosterone  secretion increases, it leads to  hypokalemia  and  muscular weakness.

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