Copeptin is increased by nausea and vomiting during hypertonic saline infusion in healthy individuals

OBJECTIVE

Measurement of hypertonic saline-stimulated copeptin has recently been described for the differentiation of polyuria-polydipsia syndrome. This study aims to determine the copeptin response to intravenous 3% hypertonic saline, including evaluation of adverse effects, in a local cohort of healthy adults >18 years in Australia.

DESIGN

Prospective clinical study.

METHODS

Twenty healthy volunteers (10 males and 10 females) were recruited. Participants underwent infusion of 3% hypertonic saline via a previously described standardized protocol, until the plasma sodium was ≥150 mmol/L, with measurement of plasma copeptin.

RESULTS

Mean peak sodium was 152 mmol/L ± SD 1.4 with osmolality 315 mmol/kg ± SD 3.9. Median volume of hypertonic saline infused to reach target sodium ≥ 150 mmol/L was 1536 mL (IQR 1362, 1992). Mean rate of plasma sodium rise was 5.9 mmol/L/hour ± SD 1.5. Hypertonic saline-stimulated copeptin had non-parametrical distribution with median of 33.8 pmol/L (IQR 27.6, 63.6). Overall median symptom burden was 6/10 (range 3/10-9/10). Copeptin was significantly higher for those who experienced nausea and/or vomiting (n = 13) (median 39.0 pmol/L; IQR 32.5, 90), compared to those participants who did not experience either (median 20.0 pmol/L; IQR 13.0, 31.0) (P = 0.003). There were no serious adverse events.

CONCLUSION

Hypertonic saline-stimulated copeptin measurements were similar in our population compared with previously reported reference intervals in healthy volunteers. There is a wide range of stimulated copeptin measurements in the healthy population. Nausea and vomiting are common adverse effects which enhance the copeptin response.

SUN-297 Development of a Local Reference Range for Hypertonic Saline-Stimulated Copeptin

Differentiating between primary polydipsia and central diabetes insipidus (DI) can be challenging. The water deprivation test has traditionally been used to diagnosis DI, however has poor diagnostic accuracy (1). Direct measurement of anti-diuretic hormone (ADH) is limited clinically. Copeptin is the C-terminal glycoprotein moiety of ADH prohormone, and correlates well with plasma ADH. Unlike ADH, copeptin is easy to measure (2).

Hypertonic saline stimulated copeptin measurements have recently been described for the diagnosis of central DI. A copeptin cut-off of >4.9 pmol/L has a diagnostic accuracy of 96.5% for distinguishing primary polydipsia from central DI (3). A copeptin assay has recently been established in our laboratory. Validation of hypertonic saline-stimulated copeptin concentrations in our local population is needed before this test can be used with confidence in patients presenting to our institution with polyuria-polydipsia syndrome. The aim of this study was to develop a local reference range for hypertonic saline-stimulated copeptin in healthy volunteers.

Twenty healthy volunteers (10 male and 10 female) were recruited. Subjects underwent a hypertonic saline test, as previously described (3). Hypertonic saline (3%) was administered as an initial 250 mL bolus followed by 0.15 mL/kg/minute until a target serum sodium of ≥150 mmol/L was reached. At this time, blood was drawn for copeptin.

Twelve healthy volunteers (7 females; 5 males) have undergone the study to date. Median age was 28 years (range 26-50); median body weight 75.7 kg (range 57.9 -94.5); median baseline plasma sodium 138 mmol/L (range 136 - 140) and median serum osmolality 289.5 (range 281-297). Median peak sodium was 152 mmol/L (range 150-154) with osmolality 314.5 mmol/kg (range 306-320). Median volume of hypertonic saline infused was 1583 mL (1230-2177) and median hypertonic saline stimulated copeptin was 29.2 pmol/L (9.6-167.4). Overall symptom burden was 5/10 (range 3/10-9/10). There were no serious adverse events.

Development of a local reference range for hypertonic saline stimulated copeptin measurements will assist in interpretation of the test in our local population of patients presenting with polyuria-polydipsia syndrome.

References

1. Fenske W, Quinkler M, Lorenz D, Zopf K, Haagen U, Papassotiriou et al. Copeptin in the differential diagnosis of the polyuria-polydipsia syndrome- revisiting the direct and indirect water deprivation tests. JCEM. 2011;96:1506-1515

2. Timper K, Fenske W, Kuhn F, Frech N, Arici B, Rutishauser J et al. Diagnostic accuracy of copeptin in the differential diagnosis of the polyuria-polydipsia syndrome: a prospective multicenter study. JCEM. 2015;100:2268-2274

3. Fenske, W, Refardt J, Chifu I, Schnyder I, Winzeler B, Drummond J. A copeptin-based approach in the diagnosis of diabetes insipidus. NEJM. 2018;379:428-439

Impulse Control Disorders in Dopamine Agonist-Treated Hyperprolactinemia: Prevalence and Risk Factors

CONTEXT

There are growing reports of dopamine agonist (DA)-induced impulse control disorders (ICDs) in hyperprolactinemic patients. However, the magnitude of this risk and predictive factors remain uncertain.

OBJECTIVE

To determine ICD prevalence and risk factors in DA-treated hyperprolactinemic patients compared to community controls.

DESIGN, SETTING AND PARTICIPANTS

Multicenter cross-sectional analysis of 113 patients and 99 healthy controls.

MAIN OUTCOME MEASURES

Participants completed a neuropsychological questionnaire consisting of the Depression Anxiety Stress Scale (DASS21), Questionnaire for Impulsive-Compulsive Disorders in Parkinson's Disease (QUIP-S), Hypersexual Behavior Inventory (HBI), Hypersexual Behavior Consequences Scale and Social Desirability Response Set Scale. Demographic and clinical data were collated to determine ICD risk factors. Patients testing positive for an ICD were offered a semistructured psychological interview.

RESULTS

Patients were more likely than controls to test positive by QUIP-S for any ICD (61.1 vs 42.4%, P = .01), hypersexuality (22.1 vs 8.1%, P = .009), compulsive buying (15.9 vs 6.1%, P = .041) and punding (18.6 vs 6.1%, P = 0.012), and by HBI for hypersexuality (8.0 vs 0.0%, P = 0.004). Independent risk factors were male sex (odds ratio [OR] 13.85), eugonadism (OR 7.85), Hardy's tumor score and psychiatric comorbidity (OR 6.86) for hypersexuality, and age (OR 0.95) for compulsive buying. DASS21 subset scores were higher in patients vs controls and in patients with vs without different ICDs. Only 19/51 (37.3%) interviewed patients were aware of the relationship between DAs and ICDs before the study.

CONCLUSIONS

DA therapy poses a high, previously underestimated risk of ICDs, especially in the form of hypersexuality in eugonadal men.

The effect of glucocorticoids on Thrombospondin-1, Osteocalcin and the Thrombospondin-1:Osteocalcin ratio in humans

OBJECTIVE

Thrombospondin-1 (TSP1), a matricellular protein, and Osteocalcin (OCN), a noncollagenous protein secreted by osteoblasts, are known to be up- and down-regulated, respectively, by glucocorticoids. The aim of this study was to determine whether a ratio between TSP1:OCN was altered by changes in glucocorticoid activity in humans.

DESIGN

Prospective observational study.

SETTING

Tertiary university hospital in Queensland, Australia.

PATIENTS AND MEASUREMENTS

Patients with Cushing's syndrome (CS, n = 19), asthma or giant cell arteritis on chronic prednisolone treatment (PRED, n = 13), adrenal insufficiency (AI, n = 16) and healthy volunteers (HV, n = 20). Plasma TSP1 and serum total OCN were measured by immunoassay at 0800h, 1200h and 1600h in patients with CS, patients with AI taking replacement glucocorticoids, HV before and after 4 mg dexamethasone and PRED patients predose at 800 and 4 hours post-dose at 1200 hours.

RESULTS

Plasma TSP1 in CS was higher (P < .0001), and serum OCN was lower (P < .0001) than HV. The TSP1:OCN ratio in HV increased significantly after 4 mg dexamethasone (P < .0001) and in AI after taking their hydrocortisone replacement therapy (P < .001). PRED patients had a higher TSP1:OCN ratio compared with HV at both 800 and 1200 hours (both P < .001), but no significant change occurred from pre- to post-dose. A TSP1:OCN ratio of >73 at 800 hours differentiated CS from HV with a sensitivity of 95% and a specificity of 100%.

CONCLUSIONS

The TSP1:OCN ratio is elevated in patients on prednisolone and in patients with CS compared with healthy volunteers. It may be a useful biomarker of total body glucocorticoid activity in humans.

Secondary adrenal insufficiency and pituitary dysfunction in oral/transdermal opioid users with non-cancer pain

Objective To evaluate pituitary function, sexual function and quality of life (QoL) in patients on oral or transdermal opioids. Design and methods Cross-sectional study comparing pituitary function, QoL and sexual function in people on long-term opioid therapy (n = 40) vs an age- and sex-matched control group (n = 25). Baseline pituitary function was assessed on blood samples collected prior to 0900 h. Further testing with corticotropin (250 µg IV) and metyrapone (30 mg/kg) stimulation tests was undertaken on participants with serum cortisol <250 nmol/L. Validated questionnaires completed to assess QoL, fatigue and sexual function. Results Secondary adrenal insufficiency (SAI) was identified on the basis of a failed stimulation test in 22.5% of opioid users vs no controls (P = 0.01). Opioid users with SAI had a higher median morphine-equivalent daily dose (MEDD), P = 0.037 - 50% with MEDD >200 mg and 0% with MEDD <60 mg had SAI. Among male participants, testosterone was inversely associated with BMI (P = 0.001) but not opioid use. A non-significant trend to low testosterone <8 nmol/L in male opioid users (11/24 opioid users vs 2/14 control, P = 0.08) suggests a small subgroup with opioid-induced androgen deficiency. Opioid users had greater fatigue, reduced quality of life in all subsections of the SF-36 and impaired sexual function in both males and females (all scores P < 0.001 compared to controls). Conclusion Long-term opioid therapy was associated with dose-related SAI in over 20% of chronic pain patients and is associated with poor quality of life, fatigue and sexual dysfunction. Obesity confounds the interpretation of opioid-induced male androgen deficiency.

Characterization of the serum and salivary cortisol response to the intravenous 250 µg ACTH1-24 stimulation test

PURPOSE

The ACTH_1-24 stimulation test is commonly used to assess the hypothalamic-pituitary-adrenal (HPA) axis. Given variations in CBG concentration and binding affinity, serum total cortisol may misclassify some patients. Salivary cortisol correlates well with serum free cortisol but is easier to measure and widely available in commercial laboratories. The aim of this study was to investigate the utility of measuring salivary cortisol during the ACTH_1-24 stimulation test.

DESIGN AND METHODS

Case-control study in a clinical research facility. Eighty-seven patients with suspected cortisol deficiency, twenty-four healthy controls, and ten healthy women on the oral contraceptive (OC) underwent an intravenous 250 µg ACTH_1-24 stimulation test. Concordance of ACTH_1-24 stimulated serum and salivary cortisol was evaluated.

RESULTS

There was a significant difference in serum cortisol between the healthy volunteers and the women on the OC (P < 0.001) but no difference in salivary cortisol. The lower limit of the reference interval for salivary cortisol at 60 min was 26 nmol/L. 27/89 (30%) of tests with suspected HPA axis disorder failed the 60 min serum cortisol cut-off of 500 nmol/L. Of these, 24/27 (89%) had a salivary cortisol of <26 nmol/L. In contrast, 12/19 (63%) tests and 5/43 (12%) tests where the 60 min serum cortisol was 500-599 and ≥600 nmol/L, respectively had a salivary cortisol of <26 nmol/L.

CONCLUSIONS

Salivary cortisol provides additional diagnostic value during the 250 µg ACTH_1-24 stimulation test in patients with proven or suspected alterations in CBG and potentially those with a borderline 60 min serum cortisol 500-599 nmol/L.

Prospective evaluation of a week one overnight metyrapone test with subsequent dynamic assessments of hypothalamic-pituitary-adrenal axis function after pituitary surgery

OBJECTIVE

To determine whether an overnight metyrapone test (OMT) within the first week postpituitary surgery can definitively assess the hypothalamic-pituitary-adrenal (HPA) axis, compared with subsequent dynamic tests and glucocorticoid requirement at 6 months.

DESIGN

Prospective study measuring morning cortisol levels on days 3 and 4 post-operatively, OMT day 5-7 and week 6, week 6 250 μg short Synacthen test (SST) and week 7 insulin tolerance test (ITT).

PATIENTS AND MEASUREMENTS

Forty participants who underwent pituitary surgery at a single centre (Cushing's disease excluded) were followed for at least 6 months. 46% had pre-operative adrenal insufficiency.

PRIMARY OUTCOME

week 1 OMT compared to glucocorticoid requirement at 6 months.

SECONDARY OUTCOMES

the performance of ITT as a "definitive" test and all tests compared to glucocorticoid requirement at 6 months.

RESULTS

Week 1 OMT showed concordance with ITT at week 7 of 78% and glucocorticoid requirement at 6 months of 81% respectively which was not significantly different from post-operative morning cortisol levels; 37% of participants with an abnormal OMT on day 6 had a normal OMT at week 6. All HPA axis tests showed similar concordance with glucocorticoid requirement at 6 months of 80%-85%.

CONCLUSIONS

Overnight metyrapone test within the first week after pituitary surgery was no better than an early morning cortisol level at predicting glucocorticoid requirement at 6 months. OMT at week 6 demonstrated recovery of HPA axis in a substantial proportion of participants who failed earlier assessments; thus, definitive testing should be delayed until 6 weeks post-operatively.

Thrombospondin-1 is a glucocorticoid responsive protein in humans

OBJECTIVE

Thrombospondin-1 (TSP1) is a matricellular protein whose gene expression has previously been shown to increase acutely after exposure to dexamethasone in vitro. The aim of this study was to determine if TSP1 is altered by acute and chronic states of glucocorticoid excess in human subjects.

DESIGN AND METHODS

Three studies have been undertaken to assess the difference or change in TSP1 in response to altered glucocorticoid activity: i) an acute interventional study assessed the effects of a single 4 mg dose of dexamethasone in 20 healthy volunteers; ii) a cross-sectional study compared plasma TSP1 in 20 healthy volunteers and eight patients with Cushing's syndrome; iii) an interventional study assessed the effect on plasma TSP1 of an increase in hydrocortisone dose from ≤20 mg/day to 30 mg/day for 7 days in 16 patients with secondary adrenal insufficiency.

RESULTS

In healthy volunteers, 4 mg dexamethasone significantly increased peripheral blood mononuclear cell (PBMC) TSP1 mRNA levels (P<0.0001) and plasma TSP1 concentrations (P<0.0001), peaking at 12 h. Median (interquartile range) plasma TSP1 was higher in Cushing's, 638 (535-756) ng/ml, than in healthy volunteers, 272 (237-336) ng/ml (P<0.0001). Plasma TSP1 >400 ng/ml diagnosed Cushing's syndrome with sensitivity of 100% and specificity of 85%. The higher hydrocortisone dose increased plasma TSP1 from 139 (86-199) to 256 (133-516) ng/ml, (P<0.01) in patients with secondary adrenal insufficiency.

CONCLUSIONS

TSP1 is a glucocorticoid responsive protein in humans. Further research is required to determine if plasma TSP1 has a role as a glucocorticoid biomarker.

Continuous subcutaneous hydrocortisone infusion therapy in Addison's disease: a randomized, placebo-controlled clinical trial

CONTEXT

Patients with Addison's disease (AD) report impaired subjective health status (SHS). Since cortisol exhibits a robust circadian cycle that entrains other biological clocks, impaired SHS may be due to the noncircadian cortisol profile achieved with conventional glucocorticoid replacement. Continuous subcutaneous hydrocortisone infusion (CSHI) reproduces a circadian cortisol profile, but its effects on SHS have not been objectively evaluated.

OBJECTIVE

The aim of this study was to determine the effect of CSHI on SHS in AD.

SETTING AND DESIGN

This was a multicentre, double-blind, placebo-controlled trial of CSHI vs oral glucocorticoid therapy. Participants received in random order 4 weeks of: CSHI and oral placebo, and subcutaneous placebo and oral hydrocortisone, separated by a 2-week washout period. SHS was assessed using the Short-Form 36 (SF-36), General Health Questionnaire (GHQ-28), Fatigue Scale (FS), Gastrointestinal Symptom Rating Scale (GSRS); and Addison's Quality of Life Questionnaire (AddiQoL). Participants were asked their (blinded) treatment preference. Twenty-four hour urine free cortisol (UFC) and diurnal salivary cortisol collections compared cortisol exposure during each treatment.

RESULTS

Ten participants completed the study. Baseline SHS scores (mean ± SE) were consistent with mild impairment: SF-36 physical component summary 48.4 (± 2.4), mental component summary 53.3 (± 3.0); GHQ-28 18.1 (± 3.3); GSRS 3.7 (± 1.6), and AddiQoL 94.7 (± 3.7). FS was similar to other AD cohorts 13.5 (± 1.0) (P = 0.82). UFC between treatments was not different (P = 0.87). The salivary cortisol at 0800 h was higher during CSHI (P = 0.03), but not at any other time points measured. There was no difference between the treatments in the SHS assessments. Five participants preferred CSHI, four oral hydrocortisone, and one was uncertain.

CONCLUSIONS

Biochemical measurements indicate similar cortisol exposure during each treatment period, although a more circadian pattern was evident during CSHI. CSHI does not improve SHS in AD with good baseline SHS. This casts some doubt on the potential benefit of circadian cortisol delivery on SHS in AD.