In chemical biology, tonicity is a measure of the effective osmotic pressure gradient; the water potential of two solutions separated by a partially-permeable cell membrane. Tonicity depends on the relative concentration of selective membrane-impermeable solutes across a cell membrane which determine the direction and extent of osmotic flux. It is commonly used when describing the swelling-versus-shrinking response of cells immersed in an external solution. Unlike osmotic pressure, tonicity is influenced only by solutes that cannot cross the membrane, as only these exert an effective osmotic pressure. Solutes able to freely cross the membrane do not affect tonicity because they will always equilibrate with equal concentrations on both sides of the membrane without net solvent movement. It is also a factor affecting imbibition. There are three classifications of tonicity that one solution can have relative to another: hypertonic, hypotonic, and isotonic.A hypotonic solution example is distilled water. Hypertonic solution
A hypertonic  is when the concentration inside the cell is high and the environment is dilute. In biology, the tonicity of a solution usually refers to its solute concentration relative to that of another solution on the opposite side of a cell membrane; a solution inside of a cell is called hypertonic if it has a greater concentration of solutes than the cytosol inside the cell and its environment is dilute. So when the cell is hypertonic(concentrated) the cell needs more water, so water is forced to enter inside the cell and the cell will swell up and eventually burst.
Glucocorticoid remediable aldosteronism also describable as aldosterone synthase hyperactivity, is an autosomal dominant disorder in which the increase in aldosterone secretion produced by ACTH is no longer transient. It is a cause of primary hyperaldosteronism. Symptoms and signs
Patients with GRA may be asymptomatic, but the following symptoms can be present:
Fatigue
Headache
High blood pressure
Hypokalemia
Intermittent or temporary paralysis
Muscle spasms
Muscle weakness
Numbness
Polyuria
Polydipsia
Tingling
Hypernatraemia
Metabolic alkalosis

Normal Physiology
Aldosterone synthase is a steroid hydroxylase cytochrome P450 oxidase enzyme involved in the generation of aldosterone. It is localized to the mitochondrial inner membrane. The enzyme has steroid 18-hydroxylase activity to synthesize aldosterone and other steroids. Aldosterone synthase is found within the zona glomerulosa at the outer edge of the adrenal cortex. Aldosterone synthase normally is not ACTH sensitive, and is only activated by angiotensin II.Aldosterone causes the tubules of the kidneys to retain sodium and water. This increases the volume of fluid in the body and drives up blood pressure.Steroid hormones are synthesized from cholesterol within the adrenal cortex. Aldosterone and corticosterone share the first part of their biosynthetic pathway. The last part is either mediated by the aldosterone synthase (for aldosterone) or by the 11β-hydroxylase (for corticosterone). Aldosterone synthesis is stimulated by several factors:
by increase in the plasma concentration of angiotensin III. by increased plasma angiotensin II, ACTH, or potassium levels. The ACTH stimulation test is sometimes used to stimulate the production of aldosterone along with cortisol to determine if primary or secondary adrenal insufficiency is present. by plasma acidosis. by the stretch receptors located in the atria of the heart.