Mineralocorticoid deficiency

Generalized distal nephron dysfunction (type IV) Mineralocorticoid deficiency or resistance Tubulointerstitial disease Drug-induced hyperkalemia... 

This is a medical emergency, and must be treated with intravenous hydrocortisone (50-100 mg 6-hourly) as intramuscular absorption may be unreliable. Patients are usually hypovolaemic and shocked, so mineralocorticoid deficiency must also be treated by using intravenous saline infusion, often requiring several liters of fluid, until the patient is well enough to take oral fludrocortisone. 

The steroid-inhibiting properties of metyrapone have also been used in the treatment of Cushing s syndrome, and it remains one of the more effective drugs used to treat this syndrome. However, the compensatory rise in corticotrophin levels in response to falling cortisol levels tends to maintain adrenal activity. This requires that glucocorticoids be administered concomitantly to suppress hypothalamic-pituitary activity. Although metyrapone interferes with lip- and 18-hydroxylation reactions and thereby inhibits aldosterone synthesis, it may not cause mineralocorticoid deficiency because of the compensatory increased production of 11-desoxycorticosterone. 

This compound, a potent steroid with both glucocorticoid and mineralocorticoid activity, is the most widely used mineralocorticoid. Oral doses of 0.1 mg two to seven times weekly have potent salt-retaining activity and are used in the treatment of adrenocortical insufficiency associated with mineralocorticoid deficiency. These dosages are too small to have important anti-inflammatory or antigrowth effects. 

The adrenal cortex secretes steroid hormones, primarily glucocorticoids and mineralocorticoids. Deficiency of these steroids results in Addison s disease, characterized by hypoglycaemia, lethargy and weight loss, anorexia and nausea and hypotension, which can be severe and may result in cardiovascular collapse. Treatment includes replacement of the missing steroids. 

The mineralocorticoid deficiency leads to a net loss of sodium ions and water into the mine with a reciprocal retention of potassium ions (hyperkalemia) and hydrogen ions (mild metabolic acidosis). The subsequent contraction of the effective plasma volume may lead to a reduction in blood pressure. If volume loss is profound, perfusion of vital tissues such as the brain could lead to lightheadedness and possible loss of consciousness. 

The most common cause of hyponatremia in hospital patients is SIADH. However, other disorders can cause dilutional hyponatremia and must be differentiated from SIADH. These conditions include (1) congestive heart failure, (2) renal insufficiency, (3) nephrotic syndrome, (4) liver cirrhosis, and (5) hypothyroidism. Excessive administration of hypotonic fluids and treatment with drugs that stimulate AVP (e.g., chlorpropamide, vincristine, clofibrate, carbamazepine, nicotine, phenothiazines, and cyclophosphamide) can cause dilutional hyponatremia as well. Hyponatremia may also occur from renal or extrarenal sodium losses (depietional hyponatremia) as a result of vomiting, diarrhea, excessive sweating, diuretic abuse, saltlosing nephropathy, or mineralocorticoid deficiency. 

Be familiar with the clinical manifestations of mineralocorticoid deficiency. 

The human body has a limited capacity to increase body stores of potassium. The major causes of hyperkalemia are excess potassium intake and mixed doses of potassium and sodium electrolyte solutions (Mahfoud et al. 2003), reduced renal losses (acute renal failure, end-stage renal disease, mineralocorticoid deficiency, potassiumsparing diuretics) and redistributions of potassium (hemolyses, necrosis, muscle injury, catecholamine antagonists, insulin deficiency, abnormal skeletal muscle sodium channels) (Peterson 1997). Increased intake by itself is rarely the sole cause of significant hyperkalemia. However, sustained hyperkalemia usually indicates an underlying defect in renal potassium excretion or impaired potassium distribution (KCl supplements or salt substitutes). The... 

Adrenal insufficiency, mineralocorticoid deficiency, osmotic diuresis, renal tubular acidosis With normal ECF volume (euvolemia) ... 

These actions on electrolyte transport, in the kidney and in other tissues e.g., colon, salivary glands, and sweat glands), appear to account for the physiological and pharmacological activities that are characteristic of mineralocorticoids. Thus, the primary features of hyperaldosteronism are positive Na balance with consequent expansion of extracellular fluid volume, normal or slight increases in plasma Na+ concentration, hypokalemia, and alkalosis. Mineralocorticoid deficiency, in contrast, leads to Na+ wasting and contraction of the extracellular fluid volume, hyponatremia, hyperkalemia, and acidosis. Chronically, hyperaldosteronism can cause hypertension, whereas aldosterone deficiency can lead to hypotension and vascular collapse. 

Mineralocorticoid deficiency syndrome Pseudohypoaldosteronism (renal tubules... 

Destruction of the adrenal cortex results in a deficiency of glucocorticoids, mineralocorticoids and androgens, and the features of the disease are a reflection of this. Mineralocorticoid deficiency leads to sodium deficiency, which in turn leads to dehydration and this can present as an Addisonian crisis. The deficiency of glucocorticoids leads to hypoglycaemia and pronounced insulin sensitivity with a flat glucose tolerance curve. Because of the glucocorticoid deficiency, the pituitary produces maximal... 

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