Measurement of salivary cortisol with liquid chromatography-tandem mass spectrometry in patients undergoing dynamic endocrine testing

OBJECTIVE

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) eliminates cross-reactivity, which is a major limitation of immunoassays used for the measurement of salivary cortisol (SalC). We aimed to evaluate the potential of SalC measured by LC-MS/MS in patients undergoing assessment of the HPA axis.

DESIGN AND PATIENTS

Cross-sectional study of 78 patients admitted for routine testing in a specialized endocrine unit.

MEASUREMENTS

Matched serum and saliva samples were collected from 68 patients who had a short synacthen test (SST, 250 mcg im) and 10 patients who had an insulin tolerance test (ITT, insulin 0.15 U/kg iv). Serum cortisol (SerC) was measured with an automated immunoassay and SalC with LC-MS/MS. Adequate SerC responses were >500 nmol/l.

RESULTS

In all patients with adequate responses, the relative increase in SalC was significantly higher than that in SerC [6.4(0.3-26.1) vs. 1.0(0.3-4.9), P < 0.0001)]. The SerC-SalC relationship was better explained by an exponential rather than a linear model (R(2)=0.83 vs. R(2)=0.65, both P < 0.0001). Based on 59 patients with adequate SerC responses to an SST, an adequate SalC response was defined as 8.3 nmol/l. Seven patients following an SST and three patients following an ITT showed inadequate responses in both SerC and SalC, but two patients with CBG deficiency showed a low SerC with normal SalC.

CONCLUSIONS

We have shown an excellent diagnostic sensitivity and specificity of LC-MS/MS SalC in the assessment of the HPA axis and superiority over SerC when CBG levels are altered. The exponential relationship between SerC and SalC supports the concept of CBG binding capacity saturation.

An update to 21-hydroxylase deficient congenital adrenal hyperplasia

Congenital adrenal hyperplasia (CAH) due to deficiency of the enzyme 21-hydroxylase (21-OH) is distinguished in classical (C-CAH) and non-classical form (NC-CAH), and it is also one of the most common autosomal recessive inherited disorders in humans. The prevalence of C-CAH is between 1:10,000 and 1:15,000 among the live neonates of North America and Europe while the NC-CAH occurs in approximately 0.2% of the general white population. The highest incidence of CAH (1:282 and 1:2141, respectively) has been evaluated in Yupik Eskimos in Alaska and in the populations of the island La Reunion (France), while the lower was detected in New Zealand newborns (0.3%). Nowadays, it has been established that except for the adrenal cortex in CAH cases, the adrenal medulla was also affected. In human 21-OH deficient adrenal gland it has been discovered that not only the chromaffin cells formed extensive neurites, expanding between adrenocortical cells, but also that the adrenal androgens promote outgrowth, whereas glucocorticoids preserve neuroendocrine cells. It seems that normal cortisol secretion by the adrenal cortex is necessary for adrenomedullary organogenesis. The synthesis of 21-OH is controlled by the active CYP21A2 gene located at a distance of 30 kb from a highly homologous pseudogene designated CYP21A1P.

Etiology of congenital hypothyroidism using thyroglobulin and ultrasound combination

Methods currently employed to establish the etiology of congenital hypothyroidism include thyroid ultrasound and scintigraphic exams. Thyroglobulin is a protein almost exclusively secreted by thyroid tissue and indirectly reflects the amount of follicular cells. Even though thyroglobulin is easy to measure, it has been not frequently used because of discordant results to distinguish mainly athyreosis and ectopy (dysgenesis). Knowing the differences in inheritance and prognosis of thyroid dysgenesis and dyshormonogenesis, it is important to define the etiology of CH, combining tools that are easy, fast and available in most medical centers. Our objective was to evaluate and compare color Doppler ultrasound and serum thyroglobulin with radionuclide scan to define the etiology of congenital hypothyroidism. We evaluated 38 children above 3 years-old off-treatment that performed serum thyroglobulin by immunofluorometric assay, color Doppler ultrasound and radionuclide study. On color Doppler ultrasound, 11 patients had athyreosis, 5 ectopic glands, being 1 associated to hemiagenesis. Twenty one had topic thyroid (3 goiters, 10 normal, 8 hypoplastic). Hemiagenesis and cystic lesion were not revealed by radionuclide scan. We observed substantial agreement between color Doppler ultrasound and radionuclide scan (kappa=0.745, p<0.0001). Serum thyroglobulin in athyreosis ranged from <1.0 to 18.7 micro g/L. Patients with ectopic glands showed wider thyroglobulin range (4.5 to 123 micro g/L, median 28.4 micro g/L). Only one patient showed thyroglobulin deficiency. By using color Doppler ultrasound and serum thyroglobulin levels as valuable combined tools, we established the etiology of congenital hypothyroidism limiting excessive and harmful exams in children, like radionuclide scan.

Study on cutoff value setting for differential diagnosis between Graves' disease and painless thyroiditis using the TRAb (Elecsys TRAb) measurement via the fully automated electrochemiluminescence immunoassay system

The purposes of this study are to set the Elecsys TRAb cutoff value by which GD and PT can be accurately diagnosed simply; and to investigate the usefulness of the vascularity index (VI) obtained from power Doppler sonography (PDS). Using 109 normal controls, 186 GD patients, and 109 PT patients who were diagnosed through Tc-99m uptake, we set the cutoff value by conducting ROC analysis on the Elecsys TRAb values. The cutoff value as a result of the ROC analysis on the Elecsys TRAb values of the normal controls and GD patients was 0.8 IU/L with 100% of sensitivity and specificity. Because all 89 cases (81.6% of the entire PT cases) with Elecsys TRAb =<0.8 IU/L are PT, the cutoff =<0.8IU/L can thus be diagnosed as PT. In contrast, because all 166 cases (88.7% of the entire GD) with Elecsys TRAb >=3.0 IU/L except for one case of PT are GD, the cutoff >=3.0 IU/L can be diagnosed as GD. So Elecsys TRAb between 0.8-3.0 IU/L was dubbed gray zone (GZ). Finally, the cutoff value of 1.5 IU/L from the ROC on the PT and GD cases was chosen as the cutoff with 96.2% of sensitivity and 94.6 of specificity. All PDS VI >=80% were GD including 4 of 6 cases with GZ and all PDS VI <50% plus Elecsys TRAb-negative cases were PT including 4 of 5 cases with GZ. In conclusion, Elecsys TRAb cutoff and VI value for differential diagnosis between GD and PT has been set successfully.

Ultrasonographic evaluation of thyroid nodules: comparison of ultrasonographic, cytological, and histopathological findings

Thyroid ultrasonography (US) and fine needle aspiration biopsy (FNAB) are the most important tools in evaluating thyroid nodules. A total of 3,404 nodules in 2,082 cases referred to our clinic between 2005 and 2008 were analyzed retrospectively. Considering US features of nodules, risk factors predicting malignancy were: margin irregularity as the most important predictor, hypoechoic pattern and microcalcification (Odds ratios: 63.2, 13.3, 7.03, respectively). Cytologic results of the patients were as follows: 1,718 (82.5%) benign, 196 (9.4%) suspicious, 68 (3.3%) nondiagnostic, and 100 (4.8%) malignant. In histopathologic examination, we determined a malignancy rate of 7.59% (158/2082). We calculated the sensitivity of FNAB as 89.16%, specificity as 98.77%, positive predictive value as 96.10%, negative predictive value as 96.39%, and accuracy as 96.32%. In cytologic examination, the malignancy rate of subcentimetric (≤1 cm) nodules was higher than supracentimetric (>1 cm) nodules (5.1% vs. 1.5%, P = 0.001). In postoperative histopathologic examination, although the malignancy rate of subcentimetric nodules was higher than that of supracentimetric nodules, the difference was statistically insignificant (5.5%, 4.4%, respectively; P > 0.05). Cytologically diagnosed malignancy was detected in 4.5% of patients with multiple nodules, while it was present in 6% of patients with solitary nodule indicating no significant difference. However, postoperative histopathologic examination revealed a significantly higher malignancy rate in patients with solitary nodule compared to in patients with multiple nodules (11.7%, 6.5%; respectively, P < 0.001). The malignancy rate of patients operated for suspicious cytology was found to be 46.15%; for nondiagnostic cytology, it was 64.29%. In conclusion, ultrasonographically, hypoechoic pattern, microcalcification and margin irregularity of thyroid nodules are important features in determining the malignancy risk. The nodule size alone still remains inadequate to exclude malignancy risk.

Role of adipocytokines in predicting the development of diabetes and its late complications

Diabetes is an important health problem since the incidence of diabetes is continuously increasing. Early diagnosis is important as type 2 diabetes begins long before we diagnose it, leading to a complicated course of the disease. In order to prevent delay in the diagnosis of type 2 diabetes, novel predictors and pathways for type 2 diabetes are mounting. Diabetic complications are common cause of morbidity and mortality among subjects with diabetes. In the pathogenesis of diabetic complications some factors other than chronic hyperglycemia may be involved. Adipocytokines play important roles in the pathogenesis of diabetes mellitus, insulin resistance, and associated metabolic conditions such as hypertension and dyslipidemia. The investigations on the role of adipocytokines in developing diabetes and its complications have been made. In this review, we discussed the implications of adipocytokines in predicting diabetes and diabetic complications, with particular attention on the roles of adiponectin, leptin, visfatin, and vaspin.

Demographic, clinical, laboratory, ultrasonographic, and cytological features of patients with Hashimoto's thyroiditis: results of a university hospital of 769 patients in Turkey

We investigated the demographic and clinical features of patients with Hashimoto's thyroiditis who had been diagnosed and treated in Ege University, the main referral center in the Aegean region of Turkey. Medical records of patients who had been followed in the endocrinology clinic of Ege University were retrospectively evaluated. Patients who had been diagnosed as having any thyroid disorder were determined. Patients with Hashimoto's thyroiditis were selected among those patients. Seven hundred and sixty-nine patients fulfilled diagnostic criteria for Hashimoto's thyroiditis (725 females, 44 males; mean age 41.76 ± 12.49 years). 62.7% of patients were between 30 and 50 years of age. 53.3% of females and 63.6% of males had diffuse enlargement of the thyroid gland. TSH level was above 4.0 IU/l in 25.6% of females and 27.4% of males. Anti-tyroglobulin antibody was positive in 92% of females and 93.2 % of males. Anti-thyroid peroxidase antibody was positive in 98.4 % of females (713 patients) and 100% of males. Thyroid ultrasonography demonstrated single nodule in 52.2% and multiple nodules in 11.3% of female patients; and single nodule 32% and multiple nodules in 20% of male patients. Fine-needle aspirations of the nodules were performed in 207 patients, and none of those biopsies was diagnosed as malignant. Women with suspicious biopsis were operated. After surgery, we found that, 2% (n = 4) of patients with FNAC diagnosis of suspicious biopsies were papillary carcinoma and the other patients (3% (n = 6)) were lymphocytic thyroiditis. Age and sex distribution and laboratory findings of our patients were comparable to the previous reports. Nodule formation was the most common ultrasonographic finding in our patients, probably due to pseudonodularity. We found four women patients with thyroid cancer in our population.

Diagnosis/differential diagnosis of Cushing's syndrome: a review of best practice

Endogenous Cushing's syndrome is an uncommon endocrine disorder that can often prove challenging, for both initial diagnosis and subsequent differential diagnosis of the underlying cause. Understanding the advantages and pitfalls of the diagnostic methods used in Cushing's syndrome is essential for accurate diagnosis and differential diagnosis, and guidelines outlining the most appropriate approaches have recently been published. We examine how current practice guidelines can be used in a real case-based scenario, and review the recommended strategies to achieve successful diagnosis and differential diagnosis.

A novel indicator of widespread endothelial damage and ischemia in diabetic patients: ischemia-modified albumin

Ischemia-modified albumin (IMA) is a novel marker of tissue ischemia. Nowadays, IMA is accepted as a marker of oxidative stress. In this study, we aimed at establishing an association between IMA and hyperglycemia, blood pressure, lipid parameters, microvascular complications, hsCRP, and microalbuminuria in type 2 diabetes patients without overt macrovascular disease and acute ischemia. Fifty type 2 diabetes mellitus patients without a history of macrovascular disease or end-stage renal disease were enrolled into the study. Age-matched 30 healthy individuals were also included in the study as a control group. Plasma IMA (0.329 ± 0.046 and 0.265 ± 0.045 AbsU; P < 0.0001) and hsCRP levels (0.51 ± 0.36 and 0.32 ± 0.17 mg/dl; P < 0.0001) were significantly higher in the diabetic group compared to healthy controls. IMA level was significantly correlated with hsCRP (r = 0.76; P < 0.0001), HbA1c (r = 0.72; P < 0.0001), microalbuminuria (r = 0.40; P = 0.004), systolic blood pressure (r = 0.28; P = 0.049), diastolic blood pressure (r = 0.44; P = 0.005), and HOMA-IR (r = 0.42; P = 0.005) levels in the entire diabetic subjects. In the diabetic patients group, presence of microalbuminuria was associated with a higher plasma IMA level (0.355 ± 0.035 and 0.265 ± 0.0045 AbsU; P < 0.0001, patients with microalbuminuria and control subjects, respectively). In the type 2 diabetes patients with nephropathy, IMA level (0.355 ± 0.035 and 0.311 ± 0.046 AbsU; P = 0.002) was determined higher compared to the diabetes patients without nephropathy. Diabetic patients without an overt cardiovascular disease still have a higher serum IMA level compared to healthy controls. The correlation of high plasma IMA levels with high hsCRP and microalbuminuria levels in diabetic subjects indicates the presence of a chronic ischemic process. Therefore, elevated IMA levels may indicate an underlying subclinical vascular disease in type 2 diabetes mellitus patients.

Diagnosis of secondary adrenal insufficiency: unstimulated early morning cortisol in saliva and serum in comparison with the insulin tolerance test

Unstimulated early morning cortisol has been suggested as a first line parameter to assess adrenal function in patients with suspected secondary adrenal insufficiency. The measurement of basal salivary cortisol (BSaC) instead of basal serum cortisol (BSeC) offers some advantages, such as painless sampling and the determination of the free hormone. The objective of this study was to evaluate the diagnostic value of BSeC and BSaC in comparison to the insulin tolerance test (ITT). Seventy-seven patients with hypothalamic-pituitary disease and 184 healthy controls were enrolled. ITT were performed in patients, and BSeC as well as BSaC levels were measured in patients and controls. Upper and lower thresholds (with >or=95% specificity either for adrenal sufficiency or adrenal insufficiency) were calculated by ROC analysis both for BSeC and BSaC. The ITT identified 41 patients as adrenal insufficient and 36 patients as adrenal sufficient. Upper and lower cutoffs were 470 and 103 nmol/l for BSeC, and 21.1 and 5.0 nmol/l for BSaC, respectively. Thereby, basal cortisol allowed a highly specific diagnosis (i.e., similar to the ITT result) in either 23% (BSeC) or 27% (BSaC) of patients. We suggest the determination of unstimulated early morning cortisol as first-line screening method for the diagnosis of secondary adrenal insufficiency. If upper and lower cutoffs are used, dynamic testing could be obviated in about one fourth of cases. Due to its easy and painless collection BSaC may be preferable to BSeC.

Pituitary tumours: pituitary incidentalomas

Clinically non-functioning pituitary adenomas range from being completely asymptomatic, and therefore being detected either at autopsy or as incidental findings on head magnetic resonance imaging (MRI) or computed tomography (CT) scans performed for other reasons (often referred to as 'pituitary incidentalomas'), to causing significant hypothalamic/pituitary dysfunction and visual field compromise due to their large size. Patients with pituitary incidentalomas should all be screened for hypersecretion (prolactin (PRL), IGF-1, midnight salivary cortisol), and those with macroadenomas should also be screened for hypopituitarism (macroadenomas) and for visual field defects if the tumour abuts the optic chiasm. Growth of non-functioning pituitary adenomas without treatment occurs in about 10% of microadenomas and 24% of macroadenomas. In the absence of hypersecretion, hypopituitarism or visual field defects, patients may be followed up by periodic screening by MRI for enlargement. Growth of a pituitary incidentaloma is an indication for surgery.

Comparison of composite whole body insulin sensitivity index derived from mixed meal test and oral glucose tolerance test in insulin resistant obese subjects

Apart from fasting blood glucose (FBG) and insulin (FBI), oral glucose tolerance test (OGTT) is also used in calculating insulin sensitivity. During OGTT, insulin secretion may not reflect normal physiological insulin secretion. Based on this idea, hepatic and whole body insulin sensitivity rates were tested during OGTT and mixed meal test (MMT) in obese subjects. Thirty-one women with Quantitative Insulin Sensitivity Check Index (QUICKI) values below 0.350 and body mass index (BMI) >or=30 were included into the study. OGTT with 75-g glucose and MMT 300 kcal were applied to all cases. Data obtained from OGTT and MMT were used in the assessment of insulin sensitivity with Hemostasis of Model Assessment-Insulin Resistance (HOMA-IR) and Matsuda's Composite Whole Body Insulin Sensitivity Index (Matsuda's ISI). Mean BMI, FBG, and FBI were 36.8 +/- 3.9 kg/m(2), 100.5 +/- 0.10 mg/dl, 16.2 +/- 5.3 microg/ml, respectively. QUICKI was 0.31 +/- 0.01 and HOMA-IR was 3.71 +/- 0.88. Matsuda's ISI derived from OGTT was 6.96 +/- 3.35 and from MMT was 11.32 +/- 6.61. In analysis, it was demonstrated that there was a correlation between HOMA-IR, QUICKI, and Matsuda's ISIs derived from OGTT and MMT. Comparing the time periods separately, it was detected that despite similar increment in insulin levels, glucose levels were higher in OGTT than MMT at 15 and 30 min. Consequently, Matsuda's ISI was demonstrated to be effectively used with the data of MMT, as used with OGTT. Moreover, MMT was shown to be in parallel to physiologic insulin secretion and reflect pancreatic functions better compared to OGTT.

Pituitary tumours: TSH-secreting adenomas

Thyrotropin-secreting pituitary adenomas (TSHomas) are a rare cause of hyperthyroidism and account for less than 2% of all pituitary adenomas. In the last years, the diagnosis has been facilitated by the routine use of ultra-sensitive TSH immunometric assays. Failure to recognise the presence of a TSHoma may result in dramatic consequences, such as improper thyroid ablation that may cause the pituitary tumour volume to further expand. The diagnosis mainly rests on dynamic testing, such as T3 suppression tests and TRH, which are useful in differentiating TSHomas from the syndromes of thyroid hormone resistance. The first therapeutical approach to TSHomas is the pituitary neurosurgery. The medical treatment of TSHomas mainly rests on the administration of somatostatin analogues, such as octreotide and lanreotide, which are effective in reducing TSH secretion in more than 90% of patients with consequent normalisation of FT4 and FT3 levels and restoration of the euthyroid state.

Cushing's disease

Cushing's syndrome refers to the clinical manifestations induced by chronic exposure to excess glucocorticoids. There are three pathological conditions that can result in the chronic overproduction of endogenous cortisol in man: the most frequent is Cushing's disease where adrenocorticotropic hormone (ACTH) is overproduced by a pituitary corticotroph adenoma, rarely ACTH can be produced in an 'ectopic' manner by a non-pituitary tumour, finally cortisol can be directly over-secreted by one or (rarely) the two adrenals that have become tumourous, either benign or malignant. The positive diagnosis of Cushing's syndrome requires that chronic hypercortisolism is unequivocally demonstrated biologically, using 24-h urinary cortisol, late-evening plasma or salivary cortisol, midnight 1-mg or the classic 48-h-low-dose dexamethasone suppression test, etc., all with essentially the same diagnosis potencies. The search for the responsible tumour then relies on the assessment of the corticotroph function, and imaging: suppressed ACTH plasma levels indicate an 'adrenal' Cushing, and the responsible unilateral adrenocortical tumour is always visible at computed tomography (CT) scan, whereas its benign or malignant nature may be difficult to diagnose before surgery. Imaging can suspect bilateral 'adrenal' Cushing, when the two adrenals are small, as in the primary pigmented nodular adrenal dysplasia associated with Carney complex, or enlarged, as in the ACTH-independent macronodular adrenocortical hyperplasia. Measurable or increased ACTH plasma levels indicate either Cushing's disease or the ectopic ACTH syndrome. When the dynamics of the corticotroph function (high-dose dexamethasone suppression test, the CRH test) are equivocal, and/or the imaging is non-contributive, it may be difficult to distinguish between the two. This is the situation where sampling ACTH plasma levels in the inferior petrosal sinus may be necessary. The best treatment option of Cushing's disease is when the responsible corticotroph adenoma can be entirely removed by the trans-sphenoidal approach, with sufficient skill to preserve the normal anterior pituitary function. When it fails, all other options directed towards the pituitary (radiation therapies), or the adrenals (medications or surgery), have numerous side effects. There is at present no recognised efficient medical treatment towards the corticotroph adenoma -still an orphan disease.

Sensitivity and specificity of pulse detection using a new deconvolution method

Quantifying pulsatile secretion from serial hormone concentration measurements (deconvolution analysis) requires automated, objective, and accurate detection of pulse times to ensure valid estimation of secretion and elimination parameters. Lack of validated pulse identification constitutes a major deficiency in the deconvolution field, because individual pulse size and number reflect regulated processes that are critical for the function and response of secretory glands. To evaluate deconvolution pulse detection accuracy, four empirical models of true-positive markers of pituitary (LH) pulses were used. 1) Sprague-Dawley rats had recordings of hypothalamic arcuate nucleus multiunit electrical activity, 2) ovariectomized ewes underwent sampling of hypothalamo-pituitary gonadotropin-releasing hormone (GnRH pulses), 3) healthy young men were infused with trains of biosynthetic LH pulses after GnRH receptor blockade, and 4) computer simulations of pulsatile LH profiles were constructed. Outcomes comprised sensitivity, specificity, and receiver-operating characteristic curves. Sensitivity and specificity were 0.93 and 0.97, respectively, for combined empirical data in the rat, sheep, and human (n = 156 pulses) and 0.94 and 0.92, respectively, for computer simulations (n = 1,632 pulses). For simulated data, pulse-set selection by the Akaike information criterion yielded slightly higher sensitivity than by the Bayesian information criterion, and the reverse was true for specificity. False-positive errors occurred primarily at low-pulse amplitude, and false-negative errors occurred principally with close pulse proximity. Random variability (noise), sparse sampling, and rapid pulse frequency reduced pulse detection sensitivity more than specificity. We conclude that an objective automated pulse detection deconvolution procedure has high sensitivity and specificity, thus offering a platform for quantitative neuroendocrine analyses.

Plasma aldosterone to renin ratio predicts treatment response in primary aldosteronism: Is volume loading needed?

Volume loading is considered the golden standard of the confirmatory tests in the diagnostics of primary aldosteronism (PA). However, it is time-consuming, and it is unclear to what extent it improves the diagnostics of PA in comparison to simple screening tests. To study this question, the diagnostics with and without oral sodium loading (OSL) were evaluated by receiver operating characteristic curves analyses in 77 consecutive OSL patients. The final diagnosis was essential hypertension in 39 cases and PA in 38 cases, determined by review of the patient records, biochemical tests, imaging findings, and the response to therapy with spironolactone and/or operation. Plasma aldosterone-to-renin-activity ratio (ARR) and daily urinary aldosterone had a good diagnostic ability that did not significantly improve by accomplishing OSL. Cut-off values with optimal sensitivity and specificity were >or=1050 pmol/l per ng/ml/h for upright ARR, and >or=45 nmol/day for daily urinary aldosterone. To conclude, carefully conducted outpatient tests are sufficient for the diagnostics of PA, when the diagnosis is justified by the positive response to treatment. However, volume loading serves as an additional diagnostic tool in the most problematic cases, improving slightly the discriminative ability of urinary aldosterone determination.

Factors other than sex steroids modulate GHRH and GHRP-2 efficacies in men: evaluation using a GnRH agonist/testosterone clamp

BACKGROUND

Sex steroids are prominent regulators of pulsatile GH secretion.

HYPOTHESIS

An experimentally controlled sex-steroid milieu will permit detection of nonsteroidal factors that determine GH secretion.

SUBJECTS

Eleven young (age, 24 +/- 0.99 yr) and 11 older (64 +/- 2.4 yr) men participated in the study.

LOCATION

The study was conducted at a tertiary medical center.

METHODS

The study consisted of GnRH-agonist down-regulation of the gonadal axis followed by fixed-dose testosterone (T) replacement (leuprolide/T clamp) and consecutive infusion of l-arginine and GHRH or GH-releasing peptide-2 (GHRP-2) to quantify peptide-secretagogue efficacies.

OUTCOMES

The experimental leuprolide/T clamp yielded statistically age-comparable total, bioavailable, and free T and estradiol (E(2)) concentrations. In this controlled milieu, sequential l-arginine/GHRH infusion stimulated 1.4-fold more (P = 0.021) and l-arginine/GHRP-2 1.3-fold more (P = 0.045) GH release in young than older men. Abdominal visceral fat (AVF) correlated negatively with both GHRH (P = 0.0006; R(2) = 0.39) and GHRP-2 (R(2) = 0.29) efficacy, whereas IGF-I positively predicted the same endpoints (R(2) = 0.25 to 0.30). In multivariate analysis, AVF emerged as a dominant negative determinant of GHRH efficacy (P = 0.002; R(2) = 0.41) and IGF-I as a primary positive determinant of GHRP-2 efficacy (P = 0.007; R(2) = 0.31).

CONCLUSION

During fixed T/E(2) availability, AVF contributes 41% of the GH-response variability to maximal GHRH drive, whereas IGF-I accounts for 31% of that for GHRP-2. Accordingly, a statistically equalized sex-steroid milieu permits dissection of age-independent and T/E(2)-independent modulators of GHRH and GHRP efficacy in men.

The relationship between central adrenal insufficiency and sleep-related breathing disorders in children with Prader-Willi syndrome

BACKGROUND

The annual death rate of patients with Prader-Willi syndrome (PWS) is high (3%). Many deaths of children are sudden and unexplained. Sleep apneas have been suggested to play a role in sudden deaths. Recently, we discovered that 60% of patients with PWS suffer from central adrenal insufficiency (CAI) during stress.

OBJECTIVE

The aim was to study the relationship between CAI and sleep-related breathing disorders.

DESIGN

In 20 children with PWS who underwent a metyrapone test (30 mg/kg at 2330 h), sleep-related breathing was evaluated by polysomnography before the metyrapone test. In addition, we recorded sleep-related breathing in 10 children with PWS during their metyrapone test. CAI was diagnosed when ACTH levels during the metyrapone test were below 33 pmol/liter at 0730 h. All tests were performed during healthy condition.

SETTING

The study was conducted in a pediatric intensive care unit and specialized sleep center.

RESULTS

Median (interquartile range) age was 8.4 yr (6.5-10.2). After metyrapone administration, median (interquartile range) central apnea index (number/hour) increased significantly from 2.2 (0.4-4.7) to 5.2 (1.5-7.9) (P = 0.007). The increase tended to be higher in children with CAI [2.8 (2.0-3.9) vs. 1.0 (-0.2 to 2.6); P = 0.09]. During polysomnography before the metyrapone test, sleep-related breathing was worse in children with CAI, who had a significantly higher central apnea index and tended to have a lower minimum oxygen saturation compared to those without CAI (P = 0.03 and P = 0.07).

CONCLUSIONS

In children with PWS, the central apnea index increased significantly after metyrapone administration, particularly in those with CAI during stress. In addition, children with CAI had a higher central apnea index compared to those without several months before the metyrapone test.

A combined dexamethasone desmopressin test as an early marker of postsurgical recurrence in Cushing's disease

CONTEXT

Recurrence of Cushing's disease (CD) after transsphenoidal surgery (TSS) occurs in about 25% of cases. Twenty percent of patients with immediate postsurgical corticotroph deficiency will present late recurrence.

OBJECTIVE

The aim of the study was to evaluate a coupled dexamethasone desmopressin test (CDDT) as a predictor of recurrence of CD.

DESIGN

We conducted a prospective bicenter study (Marseille and Grenoble, France).

PATIENTS

We studied 38 patients treated by TSS for CD with a mean follow-up of 60 months.

INTERVENTION(S)

We evaluated 24-h urinary free cortisol, ACTH, and cortisol plasmatic levels and performed low-dose dexamethasone suppression test and CDDT 3 to 6 months after surgery and then yearly.

MAIN OUTCOME MEASURES

After CDDT, ACTH ratio (ACTHr) was defined as (PeakACTH - BaseACTH)/BaseACTH. Cortisol ratio (Cortisolr) was defined as (PeakCortisol - BaseCortisol)/BaseCortisol. Basal values were observed after low-dose dexamethasone suppression test. Receiver operator characteristics curve defined ACTHr and Cortisolr giving the best sensitivity and specificity associated with recurrence.

RESULTS

Ten patients presented recurrence. ACTHr and Cortisolr were superior or equal to 0.5 in all patients with recurrence and in three of 28 patients in remission (100% sensitivity, 89% specificity). The test became positive in eight of 10 patients with recurrence 6-60 months before classical markers of hypercortisolism. Six patients with immediate postsurgical corticotroph deficiency presented recurrence. All of them presented CDDT positivity during the 3 yr after surgery, and recurrence 6 to 60 months after CDDT positivity.

CONCLUSIONS

CDDT is an early predictor of recurrence of CD and could be of particular interest in the first 3 yr after surgery, by selecting patients at high risk of recurrence despite falsely reassuring classical hormonal markers.

The insulin-like growth factor-I (IGF-I) generation test as an indicator of growth hormone status

OBJECTIVE

The aim of the study was to evaluate the IGF-I generation test (IGF-I gen) as a possible indirect test of Growth Hormone (GH) secretory status.

METHODS

Sixty-five GH deficient (GHD 1 and 2) and 86 control children were studied. Children in the GHD-1 subgroup (n=33) had low GH values (<10 microg/L) after clonidine and levo-dopa while those in the GHD-2 subgroup (n=32) had normal GH values after pharmacologic provocation but low 24-hour GH secretory rates compared to 187 Normal Statured (NS) children. Of the 86 controls, who underwent IGF-I gen,50 were NS and 36 Short-Statured (SS). Serum IGF-I was measured prior to and daily during hGH administration (hGH 0.033 mg/kg/dayx4 days).

RESULTS

The prepubertal and pubertal GHD-1 and GHD-2 children had low baseline IGF-I values but their peak IGF-I values during the IGF-I gen reached those of the controls. The percent increase of IGF-I during the test was greater in the GHD groups than in the controls; in the prepubertal groups: 516+/-58% in the GHD-1, 433+/-50% in the GHD-2, 106+/-12% in the NS, and 102+/-18% in the SS (p=0.001); in the pubertal groups: 191+/-28% in the GHD-1, 141+/-20% in the GHD-2, 48+/-8% in the NS, and 61+/-17% in the SS (p=0.003).

CONCLUSIONS

The IGF-I response during the IGF-I gen seems to reflect the GH status in children.

Establishment of reference values for endocrine tests. Part VII: growth hormone deficiency

BACKGROUND

Plasma insulin-like growth factor (IGF-I) concentration can be used as a rough indicator of the growth-hormone status. However, for the diagnosis of growth hormone deficiency, dynamic tests are required. The growth hormone (GH) response in the insulin tolerance test (ITT) is considered to be the gold standard in this respect. An alternative for the ITT is the GHRH/ GHRP-6 test, which has fewer side effects. In this study we established reference values for IGF-I levels and for the GH response in both dynamic tests.

METHODS

We studied 296 subjects recruited from the general population, equally distributed according to sex and aged between 20 and 70 years. Serum IGF-I level was measured in all subjects and an insulin tolerance test (0.15 U/kg Actrapid iv) and GHRH/GHRP-6 test (1 microg GHRH/kg and 1 microg GHRP-6/kg) were performed in 49 subjects.

RESULTS

In multivariate analyses both IGF-I and the GH response in the ITT were significantly influenced by age, whereas the GH response in the GHRH/GHRP-6 test was significantly affected by BMI. There was no sex difference in IGF-I and in the GHRH/GHRP-6 test, but in the ITT males had a higher GH peak. There was a significant correlation between the GH responses in both tests, and the GH response was significantly higher in the GHRH/GHRP-6 test than in the ITT. Age-adjusted reference values were established for each test.

CONCLUSION

We have established age-adjusted reference values for serum IGF-I and for the GH response in the ITT and GHRH/GHRP-6 test.

Analysis of treatment efficacy in girls with anorexia nervosa (III)

OBJECTIVES

So far, no unequivocal answer has been provided to the question of how to treat girls with anorexia nervosa (AN). The goal of the study was evaluation of treatment results and search for prognostic factors, regarding the outcome of administered therapy in girls with AN.

PATIENTS AND METHODS

The analysis comprised eighty-seven (87) patients with diagnosis of AN. In the course of treatment, the patients received only a balanced and highly energetic diet. The effects of dietetic procedure were evaluated, comparing clinical data and routine laboratory test results (full blood cell count, serum concentrations of sodium, potassium, glucose, cholesterol, triglycerides, total calcium, phosphates, total protein and the urea) at the onset and on the last day of hospitalisation and also an analysis of clinical data in patients with regained menstrual cycles was performed. Also, on admission to hospital, serum concentrations of TSH, FT4, FT3, E2, T and cortisol were measured (the last hormone - three times - at 8:00, 17:00 and 24:00). Moreover, a stimulation test with GnRH was performed to assess LH and FSH release. A comparison was made between the clinical data, the results of routine laboratory tests and hormone concentrations, obtained at the beginning of the therapy in the group of cured girls (the girls with regained menses) and the group, in which the therapy did not bring complete elimination of the disease.

RESULTS

After hospitalisation, 75.9% of the patients with AN continued outpatient treatment. In all the patients, who adhered to proposed therapy, menstruation cycles returned within 1 to 12 months. It was found that in the group with positive treatment outcome, the patients were older, demonstrated higher BMI values at the beginning of the therapy, as well as shorter disease duration than those in the group of patients who refused further treatment. In the group of cured patients, estradiol concentrations were significantly higher and cortisol concentrations (at 17:00 and 24:00) were significantly lower, in comparison to the uncured group.

CONCLUSIONS

The findings suggest that body weight increase by proper diet application is the most important element of therapy in AN. Patient's age, disease duration, the degree of body weight loss and serum concentrations of estradiol and cortisol at 17:00 and 24:00 are the prognostic factors for the outcome of therapy in anorexia nervosa.