Hypoglycemia in a two-year-old boy with adrenocorticotropic hormone (ACTH) deficiency (probably isolated) and adrenal medullary unresponsiveness to insulin-induced hypoglycemia

Severe Hypoglycemia due to Isolated ACTH Deficiency in Children: A New Case Report and Review of the Literature

Isolated ACTH deficiency causes life-threatening severe hypoglycemia. A 7-year-old girl with hypoglycemia due to this rare disorder is described. Our patient had undetectable plasma ACTH repeatedly and cortisol 0 mcg/dl before and after ACTH 1-24 stimulation. There was no evidence of other pituitary hormone deficiency. Glucocorticoid replacement therapy resulted in resolution of all symptoms and normalization of blood glucose. Previously published data on isolated ACTH deficiency in children is summarized. Review of the literature showed that the prevalence of this condition could be underestimated in the neonatal period and in Prader-Willi syndrome. Isolated ACTH deficiency occurs in older children as well as in neonates.

Implications of proopiomelanocortin (POMC) mutations in humans: the POMC deficiency syndrome

The recent discovery of the contribution of proopiomelanocortin (POMC)-derived peptides to the regulation of energy homeostasis and exocrine gland secretion in mice aroused new interest in the complex function of the endocrine POMC network. In addition, the first mutations in the gene encoding POMC have been identified in two patients affected by adrenal insufficiency, early onset severe obesity and red hair pigmentation. Therefore, the focus of this brief review will be the detailed discussion of the implications of these new findings in the physiology of the human POMC ligand-receptor system.

Prevention of an increase in plasma cortisol during hypoglycemia preserves subsequent counterregulatory responses

The aim of this study was to determine whether preventing increases in plasma cortisol during antecedent hypoglycemia preserves autonomic nervous system counterregulatory responses during subsequent hypoglycemia. Experiments were carried out on 15 (8 male/7 female) healthy, overnight-fasted subjects and 8 (4 male/4 female) age- and weight-matched patients with primary adrenocortical failure. 5 d before a study, patients had their usual glucocorticoid therapy replaced with a continuous subcutaneous infusion of cortisol programmed to produce normal daily circadian levels. Both groups underwent identical 2-d experiments. On day 1, insulin was infused at a rate of 1.5 mU/kg per min, and 2-h clamped hypoglycemia (53+/-2 mg/dl) was obtained during the morning and afternoon. The next morning, subjects underwent an additional 2-h hypoglycemic (53+/-2 mg/ dl) hyperinsulinemic clamp. In controls, day 2 steady state epinephrine, norepinephrine, pancreatic polypeptide, glucagon, growth hormone, and muscle sympathetic nerve activity were significantly blunted (P < 0.01) compared with day 1 hypoglycemia. In marked contrast, when increases of plasma cortisol were prevented in the patient group, day 2 neuroendocrine, muscle sympathetic nerve activity, hypoglycemic symptoms, and metabolic counterregulatory responses were equivalent with day 1 results. We conclude that (a) prevention of increases of cortisol during antecedent hypoglycemia preserves many critical autonomic nervous system counterregulatory responses to subsequent hypoglycemia; (b) hypoglycemia-induced increases in plasma cortisol levels are a major mechanism responsible for causing subsequent hypoglycemic counterregulatory failure; and (c) our results suggest that other mechanisms, apart from cortisol, do not play a major role in causing hypoglycemia-associated autonomic failure.

Pituitary gland emergencies

Emergencies in pituitary disease are not common. They can result from the failure of the pituitary gland to secrete one or more pituitary hormones, or from neuro-ophthalmological symptoms due to the mass effect of an expanding hypothalamic-pituitary tumour. Loss of hormone secretion, particularly ACTH and, to a lesser extent, TSH, can rapidly become life-threatening and requires urgent replacement therapy. Acute severe hypopituitarism should be vigorously treated as an emergency with a glucocorticoid preparation. Neuro-ophthalmological symptoms such as visual impairment, sudden onset of severe headache and alteration of the level of consciousness should prompt appropriate radiological investigations, since this may well call for emergency surgery.

Isolated adrenocorticotropic hormone deficiency associated with common variable immunodeficiency

A 14-year-old girl has been suffering from an isolated adrenocorticotropin hormone (ACTH) deficiency with secondary glucocorticoid deficiency and common variable immunodeficiency since the age of 6.6 years. Human corticotropin releasing hormone administration did not increase ACTH and cortisol levels, strongly suggesting a pituitary deficiency. Despite the profound humoral defect, severe infections have never developed and the antibody response to herpes viruses was intact. We speculate that the association between two rare disorders, simultaneously diagnosed 2 months after measles, is not coincidental but caused by close interactions between neuro-endocrine and immune systems.

Isolated ACTH deficiency with absent response to corticotrophin-releasing factor--41. Evidence for a primary pituitary defect

An 8-year-old girl presenting in hypoglycaemic coma was shown to have isolated deficiency of adrenocorticotrophic hormone (ACTH) secretion. Failure to secrete ACTH in response to intravenous administration of synthetic ovine corticotrophin-releasing factor (CRF-41) suggests that this disorder was due to a primary pituitary defect, rather than of hypothalamic origin.

Isolated familial adrenocorticotropin deficiency: prenatal diagnosis by maternal plasma estriol assay

We report on a brother and sister with adrenal insufficiency due to isolated adrenocorticotropin hormone deficiency discovered in the neonatal period. The first-born, a male infant, died; pathological findings suggested bilateral adrenal hypoplasia transmitted as an autosomal recessive trait. Plasma estriol levels were assayed during the mother's next pregnancy. The prenatal diagnosis allowed immediate and effective management of the second affected child. The supplementary evidence from the endocrine findings, unavailable on her brother, enabled us to make a diagnosis of isolated central ACTH deficiency. As the defect was found in infants of both sexes in the same family, it is in all likelihood transmitted as an autosomal recessive trait. We consider it important for genetic counselling to perform autopsies on all newborn infants whose death has no apparent cause. Maternal plasma estriol assays during pregnancy can help diagnose fetal adrenal insufficiency, whether the defect is central or adrenal.

Urinary catecholamine excretion in patients with secondary adrenocortical insufficiency

To evaluate the relationship between the secretion of cortisol and the activity of adrenal medulla in the secondary adrenocortical insufficiency, the excretion of epinephrine and norepinephrine was documented in 8 patients suffering from panhypopituitarism. Plasma levels and urinary excretion of cortisol were very low in baseline conditions, and the increase in these parameters of cortisol secretion occurring upon ACTH infusion was significantly reduced with respect to the response to ACTH documented in normal subjects. The mean value of urinary epinephrine excretion was at the lower limit of normal values, and a highly significant positive correlation was found between cortisolemia or cortisoluria and urinary epinephrine excretion in these patients. Despite a significant increase in cortisolemia and cortisoluria upon ACTH administration, this acute increase in adrenocortical activity was without any stimulatory effect on epinephrine or norepinephrine excretion. But, as in baseline conditions, a significant correlation was documented for the degree of adrenocortical activity and epinephrine excretion on the day of ACTH administration. It appears, therefore, that in severe secondary adrenocortical insufficiency the excretion of epinephrine is reduced proportionally to the decrease in adrenocortical activity.

Isolated glucocorticoid deficiency: metabolic and endocrine studies in a 5-year-old boy

A 5-year-old boy is described who presented with episodes of hypoglycaemia triggered by mild infections or fever. Subnormal glucocorticoid production was confirmed by demonstrating low urinary excretion of free cortisol, low plasma cortisol concentrations that did not rise after glucagon and ACTH stimulation, and by elevated plasma ACTH levels. The selective nature of the abnormality was confirmed by demonstrating normal plasma electrolyte concentrations and blood pressure on a salt-restricted diet. Plasma renin activity and plasma aldosterone levels were also normal and responded appropriately to salt restriction and to frusemide-induced diuresis. Starvation-induced hypoglycaemia was associated with raised levels of blood ketone bodies and low blood alanine concentrations. Catecholamine secretion during hypoglycaemia was reduced. Glucocorticoid replacement therapy was effective in restoring normal glucose homeostasis.

Isolated ACTH deficiency with transitory GH deficiency

A nine-year-old girl, who presented with a severe hypoglycemic coma, proved to have isolated ACTH deficiency, a finding previously reported in only two children. On the initial evaluation, before any treatment, GH did not respond to provocative stimuli. On replacement therapy with hydrocortisone, normal linear growth was observed. Repeated testing while on glucocorticoids replacement four years after the initial attack revealed normal GH response to stimulation test. It is suggested that cortisol deficiency was responsible for the severe hypoglycemic coma and subnormal GH response. A similar mechanism is speculated for the normal growth observed in some patients with apparent deficiency of anterior pituitary hormones, including GH. The possibility of permanent ACTH deficiency and transitory GH deficiency following hypophysitis is discussed.

Isolated ACTH deficiency confirmed by ACTH radioimmunoassay

A 28 year old woman presented with symptoms and biochemical findings suggesting hypoglycemia. Detailed endocrine investigations indicated secondary adrenocortical insufficiency with no rise in plasma ACTH or plasma cortisol following insulin-induced hypoglycemia or vasopressin infusion. The adrenal glands however produced cortisol normally following prolonged stimulation with depot tetracosactrin. Other anterior pituitary hormones were released normally following appropriate stimulation tests. The literature on isolated ACTH deficiency is briefly reviewed, and this case represents one of the few reports in which the diagnosis has been substantiated by ACTH radioimmunoassays.

Low urinary estriol during pregnancy caused by isolated fetal ACTH-deficiency

In a 34-year-old pregnant woman, serum HPL and urinary HCG were normal, but urinary estriol was repeatedly low. A normal boy was delivered after 38 week gestation. During the neonatal period, he had hypoglycemia, muscular hypotonia and transient hyperbilirubinemia. The ACTH-test was normal, but the THS-response to metyrapone was low. Serum ACTH did not respond to insulin and metyrapone. Growth hormone, TSH and gonadotropin responses to stimuli were normal. Treatment with hydrocortisone resulted in disappearance of the symptoms. It is concluded that fetal ACTH-deficiency is one of the specific endocrine causes of low maternal estriol.

Isolated ACTH deficiency. Metabolic and endocrine studies in a 7-year-old boy

Metabolic and endocrine studies on a 7-year-old boy who presented with hypoglycaemic convulsions are reported in detail, proving the diagnosis of isolated ACTH deficiency--a rare cause of hypoglycaemia in childhood. Adrenaline secretion during insulin-induced hypoglycaemia was reduced. Low blood alanine levels occurred during starvation-induced hypoglycaemia, together with raised total blood ketone bodies; blood glucose did not increase adequately after oral alanine at this time. Hypoglycaemia in isolated ACTH deficiency appears to be due to a combination of impaired alanine mobilisation and a decreased rate of gluconeogenesis.

Endocrinological aspects at follow-up studies in neonatal hypoglycaemia

Thirty-seven cases of neonatal hypoglycaemia were studied at follow-up at the age of 2 6/12-r 9/12 years. Two of them had had hypoglycaemia were stuafter the newborn period, and another patient died in a hypoglycaemic state following surgery at 10 weeks of age. Twenty-three children had oral glucose tolerance tests and intravenous insulin tolerance tests performed. Diabetic glucose tolerance was noted in 3 children. None of them showed symptoms of diabetes mellitus, neither was there any family history of diabetes. One of these patients had experienced hypoglycaemia after the newborn period and responded with hyperinsulinism during the glucose tolerance test. The other hypoglycaemic patient showed an exaggerated insulin release in response to tolbutamide. Deficient serum cortisol response to insulin-induced hypoglycaemia was demonstrated in 7 patients and 6 of these had concomitant minimal growth hormone response. One of these patients also had a diabetic glucose tolerance. None were of short stature. It is probable that a disturbance in the hypothalamic-pituitary-adrenal axis may contribute to an impaired carbohydrate metabolism in some patients with neonatal hypoglycaemia.