Isolated ACTH deficiency confirmed by ACTH radioimmunoassay

Classification of hypoglycemic disorders

The classification of symptoms of hypoglycemia, namely, reactive versus fasting, based on segregation by timing in relation to meals is no longer useful from a clinical point of view. Every patient with neuroglycopenic symptoms, regardless of relation to food ingestion, requires comprehensive evaluation. Identification of the possible cause of hypoglycemia and selection of diagnostic modalities are facilitated by considering whether the patient appears to be healthy (with or without compensated coexistent disease) or ill (with a disease known to have a proclivity to develop hypoglycemia, or is hospitalized). Medications may mediate hypoglycemia in anybody, whether they appear healthy or ill.

Hypoglycemia

The diagnosis of a hypoglycemic disorder requires a high level of suspicion, careful assessment of the patient for the presence of mediating drugs or predisposing illness, and, when indicated, methodic evaluation of the basis of well-defined diagnostic criteria. The diagnostic burden is heaviest for healthy-appearing persons with episodes of confirmed neuroglycopenia. The author's criteria for insulin mediation of hypoglycemia are plasma insulin of 6 microU/mL or higher (radioimmunoassay), C-peptide of 200 pmol/L or higher (ICMA), proinsulin of 5 pmol/L or higher (ICMA), beta OH butyrate of 2.7 mmol/L or lower, and generous (> or = 25 mg/dL) response of plasma glucose to intravenous glucagon administered when the patient is hypoglycemic. Sulfonylurea should be sought in the plasma of any hypoglycemic patient, especially by an assay which can detect the second generation of these drugs.

Isolated adrenocorticotrophin deficiency and empty sella associated with hypothyroidism

A case of isolated ACTH deficiency is described. The patient had an empty sella and longstanding radio-iodine induced hypothyroidism. The association between isolated ACTH deficiency, empty sella and hypothyroidism is reviewed. It has not previously been recognized that the commonest endocrine association of isolated ACTH deficiency is primary thyroid failure. ACTH secretion does not recover following thyroxine replacement treatment.

Isolated adrenocorticotropic hormone (ACTH) deficiency

The case to be reported is that of a 72-year-old woman with isolated adrenocorticotropic hormone (ACTH) deficiency, who complained of anorexia and generalized malaise. The secretions of human growth hormone (HGH), prolactin (PRL), luteinizing hormone (LH), follicle stimulating hormone (FSH), and thyroid stimulating hormone (TSH) were all within normal limit. In spite of the extremely low level of cortisol, the plasma level of ACTH would not rise sufficiently, but a marked response of cortisol to ACTH stimulation was recognized. The postmortem examination revealed a decrease in basophilic or PAS-positive cells of the anterior pituitary gland which also showed a selective loss of ACTH-secreting cells over immunohistochemical study. Electron microscope could easily visualize somatotroph, mammotroph, thyrotroph, FSH- and LH-gonadtroph, but corticotroph was difficult to be discerned. Adrenocortical cells demonstrated atrophy and degeneration, for which the zona fasciculata and zona reticularis were narrowed. The zona glomerulosa was slightly enlarged in width.

Primary hypothyroidism associated with secondary adrenocortical insufficiency

A 50 year old man is described in whom primary hypothyroidism and isolated ACTH deficiency leading to adrenocortical insufficiency occurred simultaneously. Low thyroid hormone levels, elevated serum TSH values and high titers of antithyroid antibodies (ATA) were consistent with primary hypothyroidism. The diagnosis of secondary adrenocortical insufficiency was based on low cortisol and ACTH morning levels, low urinary steroids, a significant increase of cortisol levels after 0.25 mg tetracosactide iv, an absence of ACTH and cortisol release after insulin-induced hypoglycemia and a similar absence of ACTH and 11-deoxycortisol increase after metyrapone administration. After one year treatment and five days withdrawal of cortisol administration, the insulin-induced hypoglycemia still failed to elicit secretory responses of ACTH and cortisol, despite the normalization of thyroid hormone levels. The etiopathogenesis of these two coexisting endocrine deficiencies is discussed.