Acquired prolactin deficiency (APD) after treatment for Cushing's disease is a reliable marker of irreversible severe GHD but does not reflect disease status

Neuropsychological complications of hypoprolactinemia

Prolactin (PRL) is primarily produced by the pituitary lactotrophic cells and while initially named for its role in lactation, PRL has several other biological roles including immunomodulation, osmotic balance, angiogenesis, calcium metabolism, and appetite regulation. Most of the PRL-related literature has traditionally focused on hyperprolactinemia, whereas hypoprolactinemia has received little attention. There is evidence to suggest that PRL receptors are widely distributed within the central nervous system including the limbic system. Furthermore, PRL has been shown to play key role in the stress regulation pathway. Recent data also suggest that hypoprolactinemia may be associated with increased sexual dysfunction, anxiety, and depression. In this paper we discuss the current understanding regarding the neuropsychological impact of hypoprolactinemia and highlight the need for adequately defining hypoprolactinemia as an entity and consideration for future replacement therapies.

Growth hormone (GH) deficiency and GH replacement therapy in patients previously treated for Cushing's disease

Several complications associated with active Cushing's disease may persist even years after complete and successful therapeutic remission of hypercortisolism. Growth hormone deficiency (GHD) shares many clinical features seen in patients with Cushing's disease, and its presence after disease remission (GHD-CR) might negatively influence and potentially worsen the systemic complications caused by previous hypercortisolism. GHD-CR is more prevalent in women, and compared to other causes of GHD, patients are younger at the onset of the pituitary disease, at diagnosis of GHD-CR and at start of GH therapy; prevalence of pituitary macroadenomas and visual abnormalities are lower, while prevalence of diabetes, hypertension, low bone mass, fractures, and worst quality of life, are higher. Serum IGF-1 levels are not useful for the diagnosis of GHD-CR and the application of GH stimulating tests requires some special attention in addition to the general recommendations for detecting GHD from other etiologies. In patients with active hypercortisolism, GH secretion is completely suppressed, but it may spontaneously and progressively recover over the years following successful therapy, meaning that GH testing may be performed at an appropriate time after remission for the correct diagnosis. Moreover, if the patient presents concomitant adrenal insufficiency, GH testing should only be carried out under adequate cortisol replacement therapy. GH therapy in children with GHD-CR improves adult height in the majority of patients, while GH therapy in adults has been associated with improvements in body composition, lipid profile and quality of life, but also with worsening of glucose metabolism.

Growth hormone deficiency in adults with Cushing's disease

Growth hormone deficiency (GHD) generally occurs in patients with Cushing's disease (CD) as a consequence of cortisol excess. Mass effect may contribute to the development of GHD in the minority of patients with CD due to corticotroph macroadenomas. Patients with CD in remission are at considerable risk of GH deficiency as a consequence of pituitary surgery or radiation therapy. The purpose of the present review is to summarize data on GH deficiency in adults with CD. Untreated GH deficiency is associated with increased visceral adiposity, decreased lean mass, bone mass, and exercise capacity, impaired linear growth (in children), dyslipidemia, insulin resistance and impaired quality of life. Evaluation and treatment of GHD should be considered in patients with CD in remission. Serum insulin-like growth factor I (IGF-I) can be helpful in the diagnosis of GHD among patients with multiple additional pituitary hormone deficiencies. The diagnosis of GHD generally requires dynamic testing, including insulin, glucagon or macimorelin stimulation. Growth hormone replacement may improve body composition, bone density, linear growth (in children), exercise capacity, dyslipidemia and quality of life. While generally safe, GH replacement requires careful monitoring to assure effectiveness and tolerance in treated patients.

Treatment of Cushing's Syndrome: An Endocrine Society Clinical Practice Guideline

OBJECTIVE

The objective is to formulate clinical practice guidelines for treating Cushing's syndrome.

PARTICIPANTS

Participants include an Endocrine Society-appointed Task Force of experts, a methodologist, and a medical writer. The European Society for Endocrinology co-sponsored the guideline.

EVIDENCE

The Task Force used the Grading of Recommendations, Assessment, Development, and Evaluation system to describe the strength of recommendations and the quality of evidence. The Task Force commissioned three systematic reviews and used the best available evidence from other published systematic reviews and individual studies.

CONSENSUS PROCESS

The Task Force achieved consensus through one group meeting, several conference calls, and numerous e-mail communications. Committees and members of The Endocrine Society and the European Society of Endocrinology reviewed and commented on preliminary drafts of these guidelines.

CONCLUSIONS

Treatment of Cushing's syndrome is essential to reduce mortality and associated comorbidities. Effective treatment includes the normalization of cortisol levels or action. It also includes the normalization of comorbidities via directly treating the cause of Cushing's syndrome and by adjunctive treatments (eg, antihypertensives). Surgical resection of the causal lesion(s) is generally the first-line approach. The choice of second-line treatments, including medication, bilateral adrenalectomy, and radiation therapy (for corticotrope tumors), must be individualized to each patient.

GH secretion reserve in subclinical hypercortisolism

PURPOSE

In overt hypercortisolism, growth hormone (GH) secretion is decreased and normalizes after surgery. In subclinical hypercortisolism (SH), GH secretion has been scarcely investigated. We assessed GH reserve in patients with and without SH and, in the former, also after recovery.

METHODS

We enrolled 24 patients with adrenal adenomas, 12 with SH (SH+, 8 females, 58.3 ± 6.5 years) and 12 without SH (SH-; 11 females, 61.8 ± 10.6 years). SH was diagnosed in the presence of ≥ 2 out of: 1 mg overnight dexamethasone suppression test >83 nmol/L, urinary free cortisol (UFC) >193 nmol/day and ACTH levels <2.2 pmol/L. GH secretion was assessed by GHRH + Arginine test (GHRH-ARG) and age-adjusted serum IGF-I levels, expressed as SDS (IGF-I SDS). Eight SH+ patients were re-evaluated after the recovery from SH.

RESULTS

Age, gender, body mass index (BMI) and IGF-I SDS were comparable between SH+ and SH- patients. After GHRH-ARG the mean GH peak levels (GH-P) and GH response (as Area Under Curve, GH-AUC) were lower in SH+ than in SH- patients (15.2 ± 8.1 vs 44.5 ± 30.9 μg/L, P = 0.004 and 1,418 ± 803 vs 4,028 ± 2,476 μg/L/120 min, P = 0.002, respectively), after adjusting for age and BMI. The GH-AUC and GH-P levels were negatively associated with UFC after adjusting for age and BMI (β = -0.39, P = 0.02 and β = -0.4, P = 0.020 respectively). After recovery, GH-P levels and GH-AUC increased as compared to baseline (23.7 ± 16.3 vs 15.8 ± 10.2 μg/L, P = 0.036 and 2,549 ± 1,982 vs 1,618 ± 911 μg/L/120 min, P = 0.012, respectively).

CONCLUSIONS

GH secretion reserve is decreased in SH patients and increases after the recovery.

Failure of antibody response to polysaccharide antigen in treated panhypopituitary adults

Although pituitary hormones are known to affect immune function, treated hypopituitarism is not a recognized cause of immune deficiency in humans. We set out to assess integrity of baseline and stimulated immune function in severely hypopituitary adults. Twenty-one panhypopituitary adults (group 1), on stable pituitary replacement including growth hormone, and 12 healthy volunteers (group 2) were studied. Lymphocyte subsets, pneumococcal antibody levels pre- and 1 month after polysaccharide vaccination, T cell numbers and in-vitro interferon (IFN)-gamma response were studied. There were no significant differences in T cell numbers or IFN-gamma secretion. B cell numbers were lower in group 1, especially those with low prolactin levels. Independent of this finding, nine of 21 patients in this group had low antibody response to polysaccharide antigen. This was most striking in those with low insulin-like growth factor 1 levels and appeared to be independent of the use of anti-convulsants or corticosteroid replacement. Significant humoral immune deficiency is seen in panhypopituitarism and may contribute to morbidity.

Acquired prolactin deficiency in patients with disorders of the hypothalamic-pituitary axis

Acquired PRL deficiency occurs when the anterior pituitary is functionally destroyed, and it usually accompanies other pituitary hormone deficiencies. We retrospectively investigated in an outpatient endocrine clinic of a major tertiary medical center the prevalence and clinical characteristics of acquired PRL deficiency in patients with diseases of the hypothalamic-pituitary axis. The study included 100 consecutive patients, 61 men and 39 women, aged 4-79 yr at diagnosis. Patients were divided by PRL level to normal (>5 ng/ml), mild (3-5 ng/ml), and severe deficiency (<3 ng/ml). Twenty-seven patients (27%) had PRL deficiency, 13 mild deficiency and 14 severe deficiency. Patients with severe PRL deficiency tend to be younger at diagnosis (mean age, 37.5+/-21.8 yr) than patients with normal PRL (46+/-18.5 yr; ns). Underlying diseases including pituitary apoplexy, non-functioning pituitary adenoma, craniopharyngioma, and idiopathic hypogonadotropic hypogonadism were associated with PRL deficiency. The incidence of severe PRL deficiency rose with an increase in the number of other pituitary hormone deficits (ACTH, TSH, gonadotropin, vasopressin), from 0 in patients with no other deficits to 38% in patients with 4 deficits (p=0.006). Patients with severe deficiency had a mean of 3 hormone deficits compared to 1.8 in the other groups (p=0.006). PRL deficiency was significantly associated with TSH, ACTH and GH deficiency.

CONCLUSIONS

PRL deficiency is common in patients with hypothalamic-pituitary disorders, especially pituitary apoplexy and craniopharyngioma. Acquired severe PRL deficiency can be considered a marker for extensive pituitary damage and a more severe degree of hypopituitarism.

Prolactin deficiency is independently associated with reduced insulin-like growth factor I status in severely growth hormone-deficient adults

BACKGROUND

In adult life, considerable overlap in IGF-I status exists between normal and severely GH-deficient (GHD) subjects defined by conventional dynamic testing of GH secretion. IGF-I is not therefore widely viewed as a reliable diagnostic marker for GHD. Recognized factors influencing serum IGF-I level in GHD include age, gender, timing of onset of GHD, and exogenous estrogen therapy, but these do not fully explain GH/IGF-I discordance in severe GHD. The primary structures of prolactin and GH are closely related. Effects of hypoprolactinemia are not well described in humans, but laboratory studies suggest a role for prolactin in hepatic IGF-I release, possibly through a signal transducer and activator of transcription 5 (STAT5) pathway. The purpose of this study was to evaluate a potential contribution of prolactin to IGF-I status in severely GHD adults.

PATIENTS AND METHODS

Using multiple regression analysis techniques, contributions of the following variables to age-adjusted IGF-I sd scores were evaluated in 162 (85 female) GHD adults: gender, timing of onset of GHD, presence or absence of prolactin deficiency, body mass index, number of additional pituitary deficits, and underlying pathology.

RESULTS

Childhood onset GHD (P < 0.0001) and presence of prolactin deficiency (P < 0.0001) were independently associated with reduced IGF-I status. The contributions of these parameters to IGF-I sd scores were -2.55 and -2.67, respectively. Gender (P = 0.06), body mass index (P = 0.99), number of additional pituitary deficits (P = 0.64), and underlying pathology (P = 0.06) did not significantly influence IGF-I status.

CONCLUSIONS

Prolactin deficiency is independently associated with reduced IGF-I status in hypopituitary adults. It is possible that prolactin deficiency is a surrogate for the degree of severity of GHD, implying a GHD paradigm undetected by conventional GH provocative tests; alternatively, it remains plausible that circulating prolactin contributes to IGF-I release in the absence of GH, possibly through a signal transducer and activator of transcription 5 (STAT5) pathway.