Deficiency of growth hormone in an adult man case of idiopathic adrenocorticotropin deficiency

Primary Cortisol Deficiency and Growth Hormone Deficiency in a Neonate With Hypoglycemia: Coincidence or Consequence?

Cortisol and growth hormone (GH) deficiencies are causes of neonatal hypoglycemia. When they coexist, a pituitary disorder is suspected. We present an infant with hypoglycemia in whom an ACTH receptor defect was associated with transient GH deficiency. A full-term boy with consanguineous parents presented with hypoglycemia (serum glucose 18 mg/dL) at 4 hours of life with undetectable serum cortisol (<1 μg/dL). Examination showed diffuse hyperpigmentation with normal male genitalia. Patient developed hyperbilirubinemia and elevated transaminase levels. GH levels of 6.8 ng/mL and 7.48 ng/mL during episodes of hypoglycemia, peak of 9.2 ng/mL with glucagon stimulation, and undetectable IGF-1 suggested GH deficiency. Thyroid function, prolactin, and gonadotropins were normal. Baseline ACTH was elevated at 4868 pg/mL, whereas serum cortisol remained undetectable with ACTH stimulation. Hydrocortisone replacement resulted in normalization of blood glucose and cholestasis with decline in ACTH level. GH therapy was not initiated, given improvement in cholestasis and euglycemia. An ACTH receptor defect was confirmed with molecular genetic testing that revealed homozygosity for a known mutation of the melanocortin 2 receptor (MC2R) gene. At 12 weeks, a random GH level was 10 ng/mL. IGF-1 was 75 ng/mL and 101 ng/mL at 7 and 9 months, respectively. This report describes glucocorticoid deficiency from an MC2R mutation associated with GH deficiency. With glucocorticoid replacement, GH secretion normalized. Our findings are consistent with a previously stated hypothesis that physiologic glucocorticoid levels may be required for optimal GH secretion [1].

Glucocorticoids and the regulation of growth hormone secretion

Glucocorticoids modulate the secretion of growth hormone (GH) by various and competing effects on the hypothalamus and pituitary gland. The final effects of this modulation depend on hormone concentrations and the duration of exposure. The traditional hypothesis is that chronically raised levels of glucocorticoids suppress the secretion of GH. However, a functional impairment of the GH reserve might also be observed in patients with low levels of glucocorticoids, such as those with secondary hypoadrenalism, which is consistent with the model of biphasic dose-dependent effects of glucocorticoids on the somatotropic axis. This Review updates our current understanding of the mechanisms underlying the effects of glucocorticoids on the secretion of GH and the clinical implications of the dual action of glucocorticoids on the GH reserve in humans. This Review will also address the potential diagnostic and therapeutic implications of GH for patients with a deficiency or excess of glucocorticoids.

Severe cortisol deficiency associated with reversible growth hormone deficiency in two infants: what is the link?

CONTEXT

Hypoglycemia is potentially life-threatening, especially in infants, and can be due to congenital cortisol and/or GH deficiency (GHD).

CASE ILLUSTRATION

Two full-term infants had undetectable cortisol levels, but also low GH levels, at the time of severe hypoglycemia. GHD persisted for several months, even after cortisol replacement.

METHODS

Targeted molecular investigations were performed and revealed homozygous inactivating mutations in MRAP (MIM ID 609196) in patient 1 and in TPIT (MIM ID 604614) in patient 2. Because GHD is not part of the MRAP or TPIT phenotypes, we performed GH stimulation tests. These revealed that GHD had resolved by 8 months (patient 1) and 3 yr (patient 2) of glucocorticoid replacement. GH replacement was therefore stopped, hypoglycemia did not recur, and over the subsequent 10 yr, growth and puberty have proceeded normally.

CONCLUSIONS

1) Physiological glucocorticoid levels appear to be required for the development and function of the somatotrophs during infancy. 2) Eucortisolism, like euthyroidism, is required for the proper evaluation of GH secretory capacity. 3) The metabolic effect of GH replacement is essential for the maintenance of normoglycemia, especially in infants. And 4) targeted molecular investigations are a powerful tool to clarify the diagnosis in severely ill infants and to reevaluate the specific treatment they need.