Astrid Libman and Julio Libman
Adrenocortical, or corticosteroid insufficiency, is the result of decreased function of the adrenal cortex.
This functional deficit can be produced by destruction of the gland, constituting primary adrenal insufficiency or Addison's disease, or it can be secondary to a decreased secretion of ACTH, with the consequent hypofunction of the adrenal cortex. The most common causes of primary deficit are tuberculosis and autoimmune destruction of the gland, with the presence of antiadrenal antibodies in the circulation. These cases can be familial and form part of multiple endocrine deficiency syndrome, due to immunity alterations, associated with hypothyroidism due to chronic Hashimoto's thyroiditis, type I diabetes mellitus, hypoparathyroidism, hypogonadism and non-endocrine autoimmune diseases, such as vitiligo, anemia pernicious, etc.
Causes of secondary failure include hypothalamic pituitary diseases such as craniopharyngiomas, chromophobic adenomas, postpartum ischemic necrosis (Sheehan's syndrome), and use of exogenous corticosteroids. In fact, the most frequent form is the one that occurs as a consequence of the suppression of the hypolamo-hypophysoadrenal axis after the more or less prolonged administration of pharmacological doses of natural or synthetic glucocorticoids.
Pathophysiology, Symptoms and signs
The lack of specificity of the initial symptoms of adrenal insufficiency means that the diagnosis is made in any seriously ill patient without an apparent cause. The importance of a correct diagnosis is emphasized by the fact that the initiation of a specific treatment, without diagnostic certification, can induce, by inhibiting ACTH secretion, the disease for which the therapy was instituted.
Adrenocortical insufficiency can present in an acute or chronic form. The acute form, or "crisis", is generally the result of a stress situation that is superimposed on a chronic insufficiency, and in which the organism is unable to respond with an increase in the production of corticosteroids; its presentation is more common in primary adrenal insufficiency, where a glucocorticoid and mineralocorticoid deficiency coexist. It can also be the result of the abrupt withdrawal of chronic treatment with corticosteroids in pharmacological doses, of bleeding associated with anticoagulant therapy or of meningococcal sepsis.
The symptoms and signs of acute adrenal insufficiency are not specific: hypotension, asthenia, anorexia, nausea, vomiting, diarrhea, abdominal pain (possible confusion with an acute surgical abdomen), fever, confusional state (differential diagnosis with a meningeal picture).
The clinical manifestations of primary chronic adrenal insufficiency also lack specificity. The most frequent include asthenia, weight loss, digestive symptoms such as anorexia, nausea, vomiting and diarrhea, arterial hypotension and dizziness, skin and mucous pigmentation, salt hunger, manifestations of hypoglycemia, emotional instability and loss of body hair.
Cortisol deficiency is responsible for most of these manifestations. Fatigue, asthenia, and gastrointestinal symptoms, the latter attributable, at least in part, to concomitant hypo or achlorhydria, rapidly reverse with glucocorticoid administration. Hypoglycemia that occurs after a period of fasting, with confusion, coma, and incoordination, is due to the lack of gluconeogenetic action of corticosteroids and lower peripheral resistance to insulin.
Due to the decreased rate of free water excretion, the patient may suffer from water intoxication with symptoms such as confusion, flaccidity, and rarely seizures, if hyponatremia is severe.
Disruption of the negative feedback system in primary adrenal insufficiency is the cause of increased secretion of peptides with melanocyto-stimulating action derived from proopiomelanocortin, such as ACTH and MSH; this determines a generalized cutaneous mucous hyperpigmentation, more marked on the knuckles, elbows, back of the hands and palmar folds, compression sites, areolas and scars. Characteristic spots are observed on the conjunctiva, gums and oral mucosa. Vitiligo can be observed in one fifth of patients, attributable to an associated autoimmune process.
Hypotension is due to a lack of cortisol, a decrease in peripheral vascular tone and cardiac minute volume (cortisol is a positive inotropic agent) and mineralocorticoids, whose deficit determines hypovolemia and dehydration. Loss of pubic and axillary hair, in female patients, is attributable to androcorticoid deficiency. Patients with secondary adrenal insufficiency present with a constellation of symptoms and signs that guide the exact diagnosis. There is evidence of hypothalamic-pituitary disease, such as headaches and visual field alterations in the case of chromophobic adenomas or craniopharyngiomas, or a history of massive hemorrhage, sepsis or transfusions in Sheehan syndrome. There are manifestations of deficiency of other pituitary hormones and,
Patients with adrenal insufficiency due to inhibition of the hypothalamic-pituitary-adrenal axis subsequent to the administration of exogenous corticosteroids usually present a frank cushingoid appearance.
When faced with one or more of the clinical manifestations suggestive of primary chronic adrenal insufficiency, laboratory confirmation is a fundamental aspect of diagnosis.
Routine laboratory and radiology . The finding of eosinophilia (remember the eosinopenic action of corticosteroids), hyponatremia, hyperkalemia, hyperchloremic acidosis and hypercalcemia is possible. The presence of elevated plasma urea levels indicates a decrease in glomerular filtration due to hypovolemia. It is possible to find fasting hypoglycemia. The chest x-ray may show a small heart. A direct abdominal film may indicate the existence of calcifications at the adrenal level.
Hormonal studies . Plasma cortisol dosage . Plasma cortisol is subject to a circadian rhythm, with figures of 10 to 25 ug / dl in the morning hours and 5 to 15 ug / dl in the late afternoon. Morning cortisol levels below 5 ug / dl are suspicious for hypoadrenalism. However, a low isolated determination, unless it occurs in the presence of an acute clinical picture or is repeated consistently, is of little help in the diagnosis of adrenal insufficiency.
ACTH dosage . Plasma ACTH has a circadian rhythm, with morning figures that normally range between 10 and 52 pgs / ml. Patients with primary adrenal insufficiency have high levels, generally above 100 pgs / ml; conversely, those with failure secondary to a hypothalamic-pituitary lesion show low concentrations. The association of low plasma cortisol with increased ACTH is diagnostic of primary adrenal insufficiency. In cases of short-term adrenal insufficiency with preservation of a certain amount of residual functioning tissue, elevated levels of ACTH may coexist with plasma cortisol concentrations in the normal range.
Insulin hypoglycemia test . Measures the response of the hypothalamic-pituitary-adrenal system to stress caused by insulin hypoglycemia; in this sense, it is possibly the most sensitive test, and requires the presence of adrenal tissue capable of responding. By intravenous route, regular insulin is administered in doses of 0.1 U / kg of body weight, normally producing an increase in cortisol> 7 ug / dl.