DHEA-S levels in hypopituitaric patients with severe GH deficiency are strongly reduced across lifespan. Comparison with IGF-I levels before and during rhGH replacement

Androgen replacement therapy in androgen-deficient women with hypopituitarism

Hypopituitarism is a rare disorder, but its prevalence has increased as a result of an increase in secondary causes of hypopituitarism such as traumatic brain injury and cranial irradiation. Estrogen with or without progestogen (progestin) treatment is conventional therapy in women with hypopituitarism. Recent data demonstrate that women with hypopituitarism may experience marked androgen deficiency as a consequence of secondary loss of function of the adrenal cortex and/or ovaries. This deficiency is not always considered and therefore androgen therapy is not routinely prescribed. Recent clinical trials indicate that testosterone supplementation in physiological doses for androgen-deficient women with hypopituitarism may improve psychological well-being and sexual function, and increase bone mineral density and lean body mass. Dehydroepiandrosterone (DHEA; prasterone) supplementation may be an option for women with hypopituitarism who have secondary adrenal insufficiency and low levels of DHEA and DHEA sulfate. While short-term treatment with testosterone or DHEA appears to be safe, long-term safety data are lacking. Androgenic adverse effects limit the acceptability of treatment for some women. Further studies to establish the efficacy and safety of androgen treatment for long-term intervention in a larger group of hypopituitary androgen-deficient women are needed.

Dehydroepiandrosterone secretion in healthy older men and women: effects of testosterone and growth hormone administration in older men

CONTEXT

Aging is associated with diminished gonadal steroid and GH/IGF-I axis activity; whether these changes contribute to the parallel declines of dehydroepiandrosterone (DHEA) and DHEA sulfate (DHEAS) production is unknown, as are the effects of sex steroid and/or GH administration on DHEA and DHEAS production.

OBJECTIVE

Our objective was to evaluate morning DHEAS concentrations and nocturnal DHEA secretory dynamics in healthy older men and women, before and after chronic administration of sex steroid(s) alone, GH alone, sex steroid(s) combined with GH, or placebo alone.

DESIGN

We compared nocturnal DHEA secretory dynamics (2000 h to 0800 h, sampling every 20 min, analyzed by multiparameter deconvolution and approximate entropy algorithms) in healthy older (65-88 yr) men (n = 68) and women (n = 36), both before and after 26 wk of administration of sex steroid(s) alone [testosterone (T) in men or estrogen/progesterone in women], GH alone, sex steroid(s) combined with GH, or placebo alone.

RESULTS

Morning concentrations of DHEAS were lower; nocturnal DHEA pulsatile production rate, burst frequency, and amplitude were higher; and half-life was shorter in women (P < 0.05). Nocturnal integrated DHEA concentrations, total production rate, and approximate entropy did not differ significantly by sex. Because of small treatment group sizes in women, only hormone intervention results in men are presented. In men, T and T plus GH administration significantly decreased nocturnal integrated DHEA but not morning DHEAS concentrations. GH alone exerted no significant effects on nocturnal DHEA secretion or morning DHEAS.

CONCLUSIONS

Spontaneous nocturnal DHEA secretion is sexually dimorphic in healthy older individuals, and T administration decreases nocturnal DHEA secretion in older men. The clinical significance of sex steroid modulation of DHEA secretion in older persons remains to be elucidated.

Hypothalamus-pituitary-adrenal hyperactivity in human aging is partially refractory to stimulation by mineralocorticoid receptor blockade

CONTEXT

The hypothalamus-pituitary-adrenal (HPA) axis is mainly regulated by CRH, arginine vasopressin, and glucocorticoid feedback. Hippocampal mineralocorticoid receptors mediate proactive glucocorticoid feedback and mineralocorticoid antagonists, accordingly, stimulate HPA axis. Age-related HPA hyperactivity reflects impaired glucocorticoid feedback at the suprapituitary level.

DESIGN

ACTH, cortisol, and dehydroepiandrosterone (DHEA) secretion were studied in eight healthy elderly (75.1 +/- 3.2 yr) and eight young (25.0 +/- 4.6 yr) subjects during placebo or canrenoate (CAN) administration (200 mg i.v. bolus followed by 200 mg infused over 4 h).

RESULTS

During placebo administration, ACTH and cortisol areas under the curve (AUCs) in elderly subjects were higher than in young subjects (P < or = 0.01); conversely, DHEA AUCs in elderly subjects were lower than in young subjects (P = 0.002). CAN increased ACTH, cortisol, and DHEA levels in both groups. In young subjects, ACTH, cortisol, and DHEA levels at the end of CAN infusion were higher (P < or = 0.05) than after placebo. In elderly subjects, at the end of CAN infusion, ACTH, cortisol, and DHEA levels were higher (P = 0.01) than after placebo. Under CAN, ACTH and cortisol AUCs were persistently higher (P < or = 0.01) and DHEA AUCs lower (P = 0.006) in elderly than in young subjects. Cortisol AUCs after CAN in young subjects did not become significantly different from those in elderly subjects after placebo.

CONCLUSIONS

1) Evening-time ACTH and cortisol secretion in elderly subjects is higher than in young subjects; 2) ACTH and cortisol secretion in elderly subjects is enhanced by CAN but less than that in young subjects; and 3) DHEA hyposecretion in elderly subjects is partially restored by mineralocorticoid antagonism. Age-related variations of HPA activity may be determined by some derangement in mineralocorticoid receptors function at the hippocampal level.

Diagnosis and treatment of hypopituitarism: an update

Diagnosis and treatment of patients with hypopituitarism needs careful clinical evaluation and individual optimization. Symptoms of hypopituitarism are variable, often insidious in onset and dependent on the degree of hormone deficiency. Diagnosis of hypopituitarism can be straightforward by measuring reduced basal hormone levels. Frequently, dynamic stimulation tests are indicated in equivocal basal hormone levels or to diagnose partial hormone deficiencies. Knowledge of the use and limitations of these dynamic tests is mandatory for proper interpretation. Hormone replacement therapy should be individualized, taking into account possible interactions. Persisting symptoms and reduced quality of life are frequently reported, explained by, at least in part, intrinsic imperfections of hormone replacement strategies in mimicking normal hormone secretion. In the present overview, the principles of diagnosis and treatment of hypopituitarism are discussed.

The effect of growth hormone replacement therapy on adrenal androgen secretion in adult onset hypopituitarism

OBJECTIVE

Growth hormone replacement therapy in GH-deficient children is associated with enhanced adrenal androgen production, raising the possibility that GH might stimulate adrenocortical hormone secretion. This has not been extensively investigated in adults to date. GH is a potent modulator of the activity of the 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) enzyme and by altering cortisol metabolism can affect the function of the hypothalamo-pituitary-adrenal (HPA) axis and therefore potentially of adrenal androgen secretion. This study examined the effects of GH replacement in GH-deficient adults on adrenal androgen secretion.

DESIGN

Prospective study of the effect of GH replacement therapy on adrenal androgen production in patients with adult onset hypopituitarism over a 12-month period.

PATIENTS AND METHODS

Thirty adult GH-deficient patients were classified into two groups according to their cortisol responses to an insulin-induced hypoglycaemia or a glucagon stimulation test: 13 patients were adrenocorticotropic hormone (ACTH)-sufficient (nine females, age 45.1 +/- 3 years), whereas 17 patients were ACTH-deficient (11 females, age 45.5 +/- 3 years). Serum samples were collected before patients were initiated on GH replacement therapy using a dose titration regimen, and after 6 and 12 months on GH therapy for measurement of serum IGF-I, dehydroepiand-rosterone sulphate (DHEAS), Delta4-Androstenedione (A4), testosterone, cortisol, sex hormone binding globulin (SHBG) and cortisol binding globulin (CBG).

RESULTS

Six months after the initiation of GH replacement therapy, serum IGF-I levels were within the normal age-related reference range in both groups of patients and this was maintained at 12 months [in all patients 0 vs. 6 months: median (interquartile range): 92.5 ng/ml (73-116 ng/ml) vs. 191 ng/ml (159-224 ng/ml), P < 0.01]. In both ACTH-sufficient and -deficient groups of GH-deficient patients, pretreatment serum DHEAS levels were lower than the normal age-related reference range (P < 0.01); the ACTH-deficient patients had significantly lower DHEAS levels than the ACTH-sufficient patients [median (interquartile range): 0.5 micro mol/l (0.4-1.2 micro mol/l) vs. 1.5 micro mol/l (0.6-2.7 micro mol/l), P < 0.05]. Following GH replacement therapy, median levels of serum DHEAS levels rose from 1.5 micro mol/l (0.6-2.7 micro mol/l) to 1.9 micro mol/l (1.9-3.9 micro mol/l) in ACTH-sufficient patients, increasing in 11 of the 13 patients (P < 0.02). In this group, the median percentage increase from baseline was 32% at 6 months (P < 0.05). In contrast, baseline serum DHEAS levels [0.5 micro mol/l (0.4-1.2 micro mol/l)] declined in or from the measurable range in 47% of ACTH-deficient patients [median -16%; range -36-0] and only in one patient a + 0.2 micro mol/l increase was observed. GH dose requirements tended to be lower in ACTH-sufficient patients [1.2 U/day (0.8-1.4 U/day) vs. 1.6 U/day (1.0-2.0 U/day); P = 0.062]. There were no significant changes in serum testosterone, A4, SHBG and/or CBG levels, compared to the pretreatment levels, in either group of patients over the 12 months of GH replacement.

CONCLUSIONS

This study shows that median serum DHEAS levels are significantly lower in GH-deficient patients, even those with intact ACTH reserve, than in aged-matched controls. GH replacement therapy is associated with a significant increase in mean serum DHEAS only in ACTH-sufficient patients. These findings are consistent with either (i) GH stimulation of adrenal androgen production in the permissive presence of ACTH or (ii) an inhibitory effect of GH on 11beta-HSD type 1 activity leading to enhanced cortisol clearance, subsequent activation of the HPA axis and ACTH-mediated androgen secretion.

Hypopituitaric patients with corticotropin insufficiency show marked impairment of the cortisol response to ACTH (1-24) independently of the duration of the disease

It is widely accepted that the classical dose of 250.0 microg ACTH (1-24) (tetracosactin) is clearly supra-maximal while 1.0 and 0.03 microg have been shown as the maximal and the lowest stimulatory ACTH doses for cortisol (F) secretion in normal young subjects. Testing with low ACTH dose would better evaluate adrenal sensitivity to corticotropin. The aims of the present study were: a) to clarify the adrenal sensitivity to ACTH in patients with different duration of corticotroph insufficiency by testing with low and very low tetracosactin doses; and b) to evaluate diagnostic implication regarding the ability of ACTH tests to distinguish patients with corticotroph insufficiency from normal subjects. In 24 hypopituitaric patients (HYPOPIT, 15 male and 9 female, age 22-50 yr, BMI: 22-26 kg/m2) with corticotrophin deficiency we studied the F, DHEA and aldosterone (A) responses to challenges with low ACTH doses (0.06 or 0.5 microg iv at 0 min) followed by 250 microg iv (at +60 min). The results in HYPOPIT were compared with those recorded in 12 normal controls (NS, 6 male and 6 female, age 22-34 yr, BMI: 20-25 kg/m2). Basal F and DHEA levels in HYPOPIT were lower than in NS, while A levels were similar in both groups. The F responses to ACTH in HYPOPIT were dose-independent and markedly lower (p < 0.0001) than in NS. After the 0.06 and 0.5 microg ACTH dose, 16% of HYPOPIT patients showed AF peak within the range of normal response. No HYPOPIT showed AF peak within the normal range after 250 microg ACTH. The DHEA responses to ACTH in HYPOPIT were dose-independent and markedly lower than in NS (p < 0.0001). Overlap between individual DHEA responses in HYPOPIT and NS was present after 0.06 microg and 0.5 microg but not after 250 microg tetracosactin. The A responses in HYPOPIT were dose-dependent and overlapped with those in NS. The adrenal responses to ACTH in HYPOPIT were not associated with the duration of the disease. In conclusion, the present study shows that the mean F and DHEA but not the A responses to ACTH (1-24) are markedly impaired in hypopituitaric patients with corticotroph insufficiency independently of the duration of the disease. The impaired F and DHEA response to ACTH is also independent of the dose, suggesting the existence of relatively enhanced sensitivity of the fasciculata and reticularis adrenal zone to ACTH but meantime remarkable impairment of the adrenal function due to corticotrophin deficiency. In the present study, testing with submaximal ACTH doses did not distinguish patients with secondary adrenal insufficiency from normal subjects.

Association of RET codon 691 polymorphism in radiation-induced human thyroid tumours with C-cell hyperplasia in peritumoural tissue

The RET proto-oncogene encodes a protein structurally related to transmembrane receptors with an intracellular tyrosine kinase domain. In human thyroid gland, the RET proto-oncogene is normally expressed in parafollicular C-cells. Thyroid C-cell hyperplasia is associated with inherited medullary thyroid carcinomas and is considered as a pre-neoplastic stage of C-cells disease. It has also been observed in thyroid tissues adjacent to follicular and papillary carcinomas. In order to study the relationship between a misfunctioning of the RET proto-oncogene and the presence of C-cell hyperplasia, we compared a series of thyroid glands presenting sporadic or radiation-associated tumours, as well as samples of unrelated normal thyroid tissues, for alteration in exons 10 and 11 of the gene and for the presence or absence of C-cell hyperplasia. Here we report a significantly higher frequency of C-cell hyperplasia present in peritumoural thyroid tissues of radiation-induced epithelial thyroid tumours, than in peritumoural of sporadic thyroid tumours or in control normal thyroid tissues (P=0.001). A G691S RET polymorphism was present with a higher frequency in radiation-induced epithelial thyroid tumours (55%) than in sporadic tumours (20%) and in control normal thyroid tissues (15%). Interestingly, this polymorphism was associated in the majority (88%) of radiation-induced tumours with a C-cell hyperplasia in the peritumoural tissues. Several explanations for this association are discussed.

Elderly subjects show severe impairment of dehydroepiandrosterone sulphate and reduced sensitivity of cortisol and aldosterone response to the stimulatory effect of ACTH(1-24)

OBJECTIVE

Hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis in ageing has been reported both in humans and in animals and may be involved in age-related changes in body composition, structure functions and metabolism, as well as in brain ageing. Despite the supposed HPA hyperactivity and its refractoriness to negative glucocorticoid feedback, low levels of dehydroepiandrosterone (DHEA) and its sulphate have been clearly demonstrated in human ageing and may suggest another cause of age-related changes in structure function and metabolism. Thus, our aim was to verify the adrenal responsiveness to various ACTH doses in normal elderly subjects.

DESIGN

We studied cortisol (F), aldosterone (A) and DHEA responses to the sequential administration of very low, low and supramaximal ACTH1-24 doses (0.06 microg or 0.5 microg followed by 250 microg ACTH1-24 i.v. at 0 and +60 minutes) in healthy elderly subjects (ES) [six females and two males, aged 63-75 years, body mass index (BMI) 22-26 kg/m2]. The results in ES were compared with those recorded in healthy young subjects (YS) (six females and six males, aged 22-34 years, BMI 20-25 kg/m2).

RESULTS

Basal DHEA levels in ES were lower (P < 0.05) than in YS, while F and A levels were similar in both groups. DHEA, F and A responses to ACTH were dose-dependent in both groups. In ES, however, DHEA levels showed no response to the 0.06 microg dose, a modest increase after 0.5 microg and a clearer rise after 250 microg ACTH; at any dose, the DHEA response in ES was clearly lower than in YS (P < 0.04). The F responses to 0.5 microg and 250 microg ACTH in ES were similar to those in YS; whereas, in ES, 0.06 microg ACTH elicited a non significant F increase which was significantly lower than in YS (P < 0.05). Similarly, the A responses to the highest ACTH doses were similar in both groups but, in ES, 0.06 microg ACTH elicited no increase in A secretion, which was clearly lower than in YS (P < 0.03).

CONCLUSIONS

Normal elderly subjects show severe reduction of DHEA response to a wide range of ACTH doses, in agreement with peculiar impairment of the activity of the adrenal reticularis zone in ageing. In contrast to young adults, elderly subjects also show no cortisol and aldosterone response to a very low ACTH dose. This evidence indicates a reduced sensitivity to ACTH in the fasciculata and glomerulosa zones of the adrenal gland in ageing.