Adrenocortical insufficiency (hypoadrenalism)

Three types of adrenocortical hypofunction are distinguished:

1. Primary adrenocortical insufficiency caused primarily by the disease of the adrenal glands. Two forms are described: 1) acute or «adrenal crisis», and 2) chronic or «Addison's disease».

2. Secondary adrenocortical insufficiency resulting from diminished secretion of ACTH.

3. Hypoaldosteronism characterised by deficient secretion of aldosterone.

Primary acute adrenocortical insufficiency (adrenal crisis)

Sudden loss of adrenocortical function may result in an acute condition called adrenal crisis.

Etiopathogenesis. Causes of acute insufficiency are:

1. Bilateral adrenalectomy.

2. Septicaemia e.g. in endotoxic shock and meningococcal infection. 

3. Rapid withdrawal of steroids.

4. Any form of acute stress in a case of chronic insufficiency i.e. in Addison's disease.

Clinical features.

1. Deficiency of mineralocorticoids (i.e. aldosterone deficiency) results in salt deficiency, hyperkalaemia and dehydration.

2. Cortisol deficiency leads to hypoglycaemia, increased insulin sensitivity and vomiting.         

Primary chronic adrenocortical insufficiency (Addison's disease)

Progressive chronic destruction of more than 90% of adrenal cortex on both sides results in an uncommon clinical condition called Addison's disease.

Causes: tuberculosis, autoimmune or idiopathic adrenalitis, histoplasmosis, amyloidosis, metastatic cancer, sarcoidosis.

Clinical Features. Clinical manifestations develop slowly.

1. Asthenia i.e. progressive weakness, weight loss and lethargy as the cardinal symptoms.

2. Hyperpigmentation,

3. Arterial hypotension.

4. Loss of appetite, nausea, vomiting and upper abdominal pain.

5. Lack of androgen causing loss of hair in women.

6. Episodes of hypoglycaemia.

7. Biochemical changes include reduced GFR, acidosis, hyperkalaemia and low levels of serum sodium, chloride and bicarbonate. Plasma ATCH level is elevated.

Secondary adrenocortical insufficiency

This condition is the result of ACTH deficiency. ACTH deficiency may appear in 2 settings:

1. Selective АСTН deficiency due to prolonged administration of high doses of glucocorticoids. This leads to suppression of ACTH release from the pituitary gland.

2. Panhypopituitarism.

Clinical features of secondary adrenocortical insufficiency are like those of Addison's disease except the following:

1. These cases lack hyperpigmentation because of suppressed production of melanocyte-stimulating hormone (MSH) from the pituitary.

2. Plasma ACTH levels are low-to-absent in secondary insufficiency but are elevated in Addison's disease.

3. Aldosterone levels are normal due to stimulation by renin.

Hypoaldosteronism

Aldosterone is steroid hormone secreted by the adrenal cortex that regulates the salt and water balance in the body. Isolated deficiency of aldosterone with normal cortisol level may occur in association with reduced renin secretion.

Etiopathogenesis. The causes of hyporeninism are:

1. Congenital defect due to deficiency of an enzyme required for its synthesis.

2. Prolonged administration of heparin.

3. Certain diseases of the brain.

4. Excision of an aldosterone-secreting tumour.

Clinical features. The patients with isolated hypoaldosteronism are adults with mild renal failure and diabetes mellitus. The predominant features are hyperkalaemia and metabolic acidosis.

Pheochromocytoma

Pheochromocytoma is generally a benign tumour arising from the adrenal medulla. Pheochromocytoma may occur at any age but most patients are 20-60 years old. These tumours are commonly sporadic but about 10-20% are associated with familial syndromes of multiple endocrine neoplasia (MEN); and are associated with medullary carcinoma of the thyroid, hyperparathyroidism, pituitary adenoma, mucosal neuromas and von Recklinghausen's neurofibromatosis in varying combinations.

The clinical features of pheochromocytoma are predominantly due to secretion of catecholamines, both epinephrine and norepinephrine. The most common feature is hypertension. Other manifestations due to sudden release of catecholamines are congestive heart failure, myocardial infarction, pulmonary oedema, cerebral haemorrhage, and even death.