Desmopressin Stimulation Test in a Pregnant Patient with Cushing‚Äôs Disease

https://doi.org/10.1016/j.aace.2021.11.005Get rights and content
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Highlights

‚ÄĘ

Due to the physiologic rise of ACTH during pregnancy, unstimulated ACTH levels may not be an accurate marker to differentiate between adrenal and ACTH-independent Cushing’s syndrome.

‚ÄĘ

The desmopressin stimulation test can be done during pregnancy to investigate the etiology of Cushing’s syndrome.

‚ÄĘ

Non-gadolinium enhanced pituitary imaging may not detect pituitary adenoma, which is the most common cause of Cushing’s disease. Contrast-enhanced pituitary magnetic resonance imaging should be considered in pregnant women with ACTH-dependent Cushing’s syndrome.

‚ÄĘ

Due to increase maternal and fetal morbidities in active Cushing’s syndrome, prompt diagnosis and appropriate treatment are essential. The treatment of choice is transsphenoidal surgery during the second trimester, preferably at a high-volume pituitary center.

‚ÄĘ

There were significantly lower rates of fetal complications in women with active Cushing’s syndrome than a cured disease, including low birth weight.

Abstract

Objective

The hypothalamic-pituitary-adrenal axis stimulation during pregnancy complicates the investigation of Cushing’s syndrome. Our objective is to present a pregnant patient with Cushing syndrome caused by pituitary tumor in which the desmopressin stimulation test helped in the diagnosis and led to appropriate management.

Case report

A 27-year-old woman with 9-week gestation presented with proximal myopathy for 2 months. She had high blood pressure, wide abdominal purplish striae, and proximal myopathy. Her past medical history revealed hypertension and dysglycemia for 1 year. The 8 AM cortisol was 32.4¬†őľg/dL (5-18), late-night salivary cortisol at 11 PM was 0.7¬†őľg/dL (<0.4), and the mean 24-hour urinary free cortisol was 237.6¬†őľg/day (21.0-143.0). The mean ACTH concentrations at 8 AM were 44.0 pg/mL (0-46.0). Non-gadolinium enhanced pituitary magnetic resonance imaging (MRI) reported no obvious lesion. The desmopressin stimulation test showed a 70% increase in ACTH levels from baseline after desmopressin administration. The pituitary MRI with gadolinium showed an 8x8x7-mm pituitary adenoma. Transsphenoidal surgery with tumor removal was done, which showed ACTH-positive tumor cells. After the surgery, the patient carried on the pregnancy uneventfully.

Discussion

During pregnancy, the ACTH level may not be an accurate marker to help in the differential diagnosis of Cushing’s syndrome. Moreover, non-gadolinium pituitary imaging may not detect small pituitary lesions.

Conclusion

In the present Case, the desmopressin stimulation test suggested the diagnosis of Cushing’s disease, which subsequently led to successful treatment. This suggested that the desmopressin test may serve as a useful test to diagnose Cushing’s disease in pregnant individuals.

Keywords

Cushing’s disease
Cushing’s syndrome
desmopressin stimulation test
pregnancy

Introduction

Pregnancy rarely occurs during the course of Cushing’s syndrome (CS).1,2¬†Given the increase in maternal and fetal morbidities in women with active CS, early diagnosis and treatment of CS are essential.2

The diagnosis of CS using the usual diagnostic tests is challenging due to stimulation of the hypothalamic-pituitary-adrenal axis during pregnancy. The physiologic rise of ACTH from the 7th week of pregnancy also complicates the investigation for the etiology of CS.1¬†The concern of gadolinium use during pregnancy can affect the sensitivity in detecting small pituitary lesions in ACTH-dependent CS if using non-gadolinium pituitary imaging. Desmopressin is a vasopressin analog selective for V2 receptors. The desmopressin stimulation test has been proposed as a useful procedure for the differential diagnosis of CS.3¬†Desmopressin stimulates the increase in ACTH and cortisol in patients with CS caused by pituitary tumor or Cushing’s disease (CD) but not in the majority of normal, obese subjects and patients with adrenal CS or ectopic ACTH syndrome.3,4¬†However, there were limited data on the desmopressin stimulation test during pregnancy.

Here we present the 27-year-old woman with CS in which the desmopressin stimulation test helped in the diagnosis of CD and led to successful treatment.

Case presentation

A 27-year-old woman with 9-week gestation was referred from the orthopedic department to evaluate CS. She presented with proximal myopathy for 2 months. On physical examination, she had Cushingoid appearance, wide purplish striae, bruising, and proximal muscle weakness. Her blood pressure was 160/100 mmHg, and her body mass index was 32.2 kg/m2. Her past medical history revealed that she had hypertension, dyslipidemia, and impaired fasting glucose for 1 year without taking any medication. She also gained 20 kg in the past 2 years. The 8 AM cortisol (chemiluminescent immunometric assay, Immulite/Siemens) was 32.4¬†őľg/dL (normal , 5.0-18.0), late-night salivary cortisol at 11 PM (electrochemiluminescence immunoassay, Roche Cobas) was 0.7¬†őľg/dL (normal, <0.4), and the mean 24-hour urinary free cortisol (UFC) (radioimmunoassay, Immulite/Siemens) was 237.6¬†őľg/day (normal, 21.0-143.0). ACTH concentrations at 8 AM (chemiluminescent immunometric assay, Immulite/Siemens) were 48.4 and 39.6 pg/mL (normal, 0-46.0) (Table 1). At 12 weeks of gestation, non-gadolinium enhanced pituitary magnetic resonance imaging (MRI) reported a mild bulging contour of the right lateral aspect of the pituitary gland without an obvious abnormal lesion (Figure 2A). The desmopressin stimulation test was then carried out at 14 weeks of gestation. Serial blood samples for ACTH and cortisol were obtained basally (at 8 AM) and at 15, 30, 45, and 60 minutes after the intravenous administration of 10¬†őľg of desmopressin. The results were shown in¬†Table 2. Compared with baseline, ACTH levels increased from 34.7 to 58.9 pg/mL (70%) at 15 minutes after desmopressin administration (a ‚Č•35% increase in ACTH levels was considered an indication of CD in non-pregnant individuals)3¬†(Figure 1). The pituitary MRI with gadolinium revealed an 8x8x7-mm circumscribed lesion with heterogeneous iso- to hyperintensity on T2W in the right inferolateral aspect of the anterior pituitary lobe. The lesion had a delayed enhancement compared to normal pituitary tissue (Figure 2B). Non-contrast MRI adrenal glands showed bilateral normal adrenal glands without mass or nodule. Other abdominal organs were unremarkable. Regarding comorbidities, she had hypertension and gestational diabetes mellitus (GDM). The HbA1c level was 5.7% (39 mmol/mol). Using a two-step strategy, GDM was diagnosed at 12 weeks of gestation. Hypertension and GDM were controlled with 750 mg of methyldopa and 50 units of insulin per day, respectively.

Table 1. Laboratory investigations of the present Case

Variable At 9 weeks of gestation
8 AM cortisol,¬†őľg/dL (5.0-18.0) 32.4
Salivary cortisol (11 PM , <0.4¬†őľg/dL) 0.7
UFC (21.0-143.0¬†őľg/day) 183.5 and 291.6
ACTH, pg/mL (8 AM, 0-46.0) 48.4 and 39.6
DHEAS (8 AM, 35.0-430.0¬†őľg/dL) 378.0
PAC (upright position, 8 AM), ng/dL 5.2
PRA (upright position, 8 AM), ng/mL/hr 2.1
Potassium, mmol/L 3.6

UFC, urinary free cortisol; ACTH, adrenocorticotrophic hormone; DHEAS, dehydroepiandrosterone sulphate; PAC, plasma aldosterone concentration; PRA, plasma renin activity.

Figure 2. Pituitary imaging of the present Case. (A) A non-gadolinium MRI of the pituitary gland at 12 weeks of gestation showing a mild bulging contour of the right lateral aspect of the pituitary gland without an obvious abnormal lesion (B) An MRI of the pituitary gland with gadolinium at 14 weeks of gestation showing an 8x8x7-mm circumscribed lesion with heterogeneous iso- to hyperintensity on T2W in the right inferolateral aspect of the anterior pituitary lobe. The lesion had a delayed enhancement compared to normal pituitary tissue.

Table 2. Desmopressin stimulation test results performing at 14 weeks of gestation

Time 0 min 15 min 30 min 45 min 60 min
ACTH (pg/mL) 34.7 58.9 57.4 49.9 38.2
Cortisol (őľg/dL) 30.6 30.2 29.7 29.6 31.0

ACTH, adrenocorticotrophic hormone

Figure 1. Percentage of ACTH increase after desmopressin administration (time 0 min).

Transsphenoidal surgery with tumor removal was performed at 18 weeks of gestation. Pathological findings showed a 1.3×1.0x0.3 cm of tissue with segments of the pituitary gland and tumor. There were monomorphous round nuclei, stippled chromatin, indistinct nucleoli, and pale eosinophilic cytoplasm cells. These cells were reactive with ACTH and showed loss of reticulin framework, unlike the normal pituitary gland. The next day after the surgery, her 8 AM cortisol was 6.0¬†őľg/dL. Hydrocortisone supplement was started and continued throughout pregnancy. Antihypertensives were discontinued, and the insulin dosages decreased to less than 20 units per day. At 38 weeks of gestation, she gave birth to a 2300-gm male newborn (small for gestational age). Dysglycemia and hypertension resolved after the delivery. One year after the first child’s delivery, the patient had a spontaneous pregnancy without GDM or hypertension. The 8 AM cortisol was 3.9¬†őľg/dL, and hydrocortisone replacement was continued. The patient successfully delivered a term 3300-gm male infant without fetal or maternal complications. Two years after the first transsphenoidal surgery, a 1-őľg cosyntropin stimulation test was performed, the basal cortisol was 11.7¬†őľg/dL, and the peak serum cortisol was 23.8¬†őľg/dL. Steroid replacement was withdrawn.

Discussion

Herein we present a 27-year-old woman who was evaluated during her first pregnancy for clinical and laboratory features suggestive of CD. Her morning serum and late-night salivary cortisol concentrations were elevated in addition to non-suppressed ACTH, but a definitive diagnosis was not obtained by a non-gadolinium pituitary MRI. The diagnosis of CD was suggested, however, by the results of a desmopressin stimulation test. The pituitary MRI with gadolinium was proceeded and revealed a pituitary lesion greater than 6 mm.

The prevalence of pregnancy is low due to reduced fertility in CS. To date, there have been less than 300 pregnant patients with CS reported in the literature.2 In pregnancy, the most frequent etiology of CS is adrenal CS (60%), followed by ACTH-producing pituitary adenomas or CD (35%), and very rarely ectopic ACTH (<5%).1 In contrast, CD is the most common cause of CS in non-pregnant people (approximately 70 percent). The clinical diagnosis of CS during pregnancy may be missed due to overlapping features between pregnancy and CS. However, wide purplish cutaneous striae and proximal myopathy are signs with high discrimination index when CS is suspected.5 These signs are not present in normal pregnancy.

In this present Case, CS was diagnosed with apparent clinical features of CS in addition to an elevated UFC and late-night salivary cortisol. The patient denied taking any supplements and her 8 AM cortisol was not suppressed and therefore did not suggest an etiology of exogenous steroid use. Pregnant women without CS may have elevated UFC and late-night salivary cortisol due to increased total and free plasma cortisol from the first trimester until the end of pregnancy.6¬†This results from an elevated concentration of cortisol transport protein and the increase in placental ACTH and CRH. According to the current guideline, UFC is the recommended test when CS is suspected during pregnancy.5¬†Since UFC increases during the second trimester, it may not be a reliable marker after the first trimester of pregnancy unless the level is clearly increased (up to 2- to 3-fold the upper limit of normal values).1¬†Late-night salivary cortisol is also one of the useful tests to diagnose CS during pregnancy because the circadian rhythm of cortisol is preserved in normal pregnancy. Furthermore, it is not influenced by the changes in the binding proteins.7¬†However, the previous study has shown that late-night salivary cortisol increased progressively throughout pregnancy. When compared with non-pregnant women, median values of late-night salivary cortisol in pregnant women were 1.1, 1.4, and 2.1 times higher in the first, second, and third trimesters respectively. The cutoff values for late-night salivary cortisol on each gestational trimester were: first trimester 0.255¬†őľg/dL, second trimester 0.260¬†őľg/dL, and third trimester 0.285¬†őľg/dL. The respective sensitivities and specificities in each trimester were: first trimester 92 and 100%, second trimester 84 and 98%, and third trimester 80 and 93%.8

Given the non-suppressed ACTH levels after the 7th week of gestation, we were not able to summarize whether the etiology was adrenal CS or ACTH-dependent CS which could be either CD or ectopic ACTH syndrome. In non-pregnant individuals, ACTH suppression usually identifies adrenal CS. However, in pregnancy, ACTH levels were non-suppressed in half of those with adrenal CS due to continued stimulation of maternal hypothalamic-pituitary-adrenal axis by placental CRH.1 Therefore, using the ACTH thresholds in general populations can lead to misdiagnosis when investigating the etiology of CS in pregnant individuals. The hypothalamic-pituitary-adrenal axis response to exogenous glucocorticoids is blunted in pregnant women. Following an overnight dexamethasone administration, pregnant women without CS may have non-suppressed plasma cortisol and UFC.6 In non-pregnant individuals with CS, the high-dose dexamethasone suppression test identify CD with a sensitivity of 82% and a specificity of 50%.4 During pregnancy, the high-dose dexamethasone suppression test failed to identify almost half of the patients with CD.1 Inferior petrosal sinus sampling is usually avoided due to the risk of excessive radiation exposure. Since the non-gadolinium MRI also showed no obvious pituitary lesion in the present Case, in addition to the limitation of the high-dose dexamethasone suppression test and inferior petrosal sinus sampling in pregnancy, we used desmopressin stimulation to help in the investigation of CD since desmopressin can stimulate an ACTH response in a considerable proportion of patients with CD but not in most patients with adrenal CS or ectopic ACTH syndrome.3,4

Desmopressin has been assigned to pregnancy category B by the US Food and Drug Administration (FDA). In the most recent guideline update on the diagnosis and management of CD, the desmopressin stimulation test can be used to differentiate ectopic CS and CD in patients with normal or high ACTH and have no adenoma or equivocal results of pituitary MRI. However, the guideline did not mention the use of this test in pregnant individuals.9 The literature regarding the use of desmopressin stimulation tests in pregnancy is limited. We were able to identify one study in a pregnant patient with active CS, who was surgically confirmed as CD, in which the desmopressin stimulation test was performed at 10 weeks of gestation and after the delivery. Compared with age-matched healthy non-pregnant women, there were different responses of cortisol and ACTH after desmopressin administration in a pregnant patient with active CS.10 The ACTH peaks after the administration of desmopressin were higher in the pregnant patient. CRH stimulation test was also performed in the pregnant patient with CD. Desmopressin stimulated ACTH values during pregnancy and after the delivery were not significantly different, while the CRH stimulated ACTH values were significantly higher when the test was performed after the delivery. The authors did not mention optimal cutoff values for these diagnostic tests.10 In non-pregnant individuals, the ACTH increase of more than 35% at 15 minutes after the desmopressin administration gave the sensitivity of 84% and the specificity of 43% in the diagnosis of CD.3 Another recent study in ACTH-dependent CS showed that the threshold increase in the ACTH level after desmopressin stimulation of 45% identified CD with a sensitivity of 91% and a specificity of 75%.4 Using the non-pregnant cutoff values for the desmopressin stimulation test, the diagnosis of CD was made in our patient who was later surgically confirmed as CD.

Pituitary microadenomas were the cause of CD in almost 90% of non-pregnant individuals.11¬†In pregnant women with CD, pituitary microadenomas were also reported to be more common than macroadenomas.1,12¬†Almost 40% of pituitary microadenomas in CD were invisible or poorly visible in non-contrast MRI, in which contrast-enhanced MRI detected them.13¬†In the Case series from Lindsay et al., the non-contrast MRI could not correctly identify pituitary adenomas in 38% of pregnant patients with available data.1¬†The same case series reported a pregnant patient having normal pituitary MRI and was later surgically confirmed as having CD from a 3×3 adenoma with positive staining for ACTH. In the present case, a mild bulging contour of the pituitary gland, although without an obvious abnormal lesion, in addition to desmopressin test results, suggested the need for contrast-enhanced pituitary MRI. Gadolinium contrast is FDA pregnancy category C since it is water-soluble and can cross the placenta into the fetus and amniotic fluid.14¬†However, since a non-gadolinium MRI may not detect pituitary microadenoma even in patients with normal imaging results,1,15¬†we suggested physicians consider pituitary MRI with gadolinium as initial imaging in pregnant patients with clinical suspicion of CD.

Prompt diagnosis and treatment of CS are essential due to a higher rate of fetal loss in active CS patients without treatment than those who received either medical or surgical treatment. There are significantly lower rates of various fetal complications, including low birth weight, in women with active CS than in cured CS.2 Although medical and surgical treatment were not compared as prognostic factors for complications, experts recommend transsphenoidal surgery in the second trimester as the treatment of choice for CD in pregnancy.1,15 Medical treatment should be the second choice when surgery cannot be carried out or late diagnosis is made.

Conclusion

In the present Case, the results from the desmopressin stimulation test and the pituitary MRI with gadolinium suggested the diagnosis of CD, which subsequently led to successful treatment. This suggested that the desmopressin test may serve as a useful test to diagnose CD even in the context of pregnancy.

Conflicts of Interest

None of the authors have any potential conflicts of interest associated with this research.

References

Funding Statement

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Acknowledgements

The authors would like to thank you all the colleagues in the Division of Endocrinology and Metabolism, Department of Medicine, Faculty of medicine, Chulalongkorn University for all the support.

Desmopressin is Promising Alternative in Diagnosing Cushing‚Äôs Disease

Bilateral inferior petrosal sinus sampling (IPSS) ‚ÄĒ a procedure that uses desmopressin to determine levels of ACTH hormone from veins that drain from the pituitary gland, is a sensitive way to diagnose patients with Cushing‚Äôs disease and find tumors, a Chinese study shows.

The study, ‚ÄúTumour Lateralization in Cushing‚Äôs disease by Inferior Petrosal Sinus Sampling with desmopressin,‚ÄĚ appeared in the journal¬†Clinical Endocrinology.

Cushing’s disease is characterized by excessive production of the adrenocorticotropin hormone (ACTH) caused by a tumor in the pituitary gland. ACTH is the hormone that causes the adrenal glands to produce cortisol.

Currently, pituitary imaging is insufficient to confirm a Cushing’s diagnosis. This is because 70 percent of pituitary adenomas in Cushing’s are microadenomas, which are physically very small. As a result, 40 percent of Cushing’s patients are reported as being healthy.

This means that a Cushing’s diagnosis requires a combination of techniques including clinical symptoms, imaging methods and endocrinological assays that include measures of serum cortisol and ACTH levels.

IPSS determines ACTH levels from veins that drain from the pituitary gland. ACTH levels are then compared to ACTH levels in blood. Higher levels in the pituitary gland indicate a pituitary tumor.

IPSS can also be used to determine tumor lateralization, which refers to which side of the pituitary gland the tumor is located on. The test is 69 percent accurate.

Doctors administer IPSS along with corticotropin-releasing hormone (CRH) stimulation. IPSS with CRH is considered the gold standard for preoperative diagnosis of Cushing’s, with a diagnostic sensitivity (or true positive rate) of 95 percent and specificity (or true negative rate) of 90 to 95 percent. Unfortunately, the high cost and limited availability of CRH make it impractical for many patients.

Desmopressin has been used to replace CRH to stimulate ACTH secretion for IPSS, and prior studies have shown that desmopressin’s sensitivity is comparable to that of CRH.

Researchers at Peking Union Medical College in Beijing conducted a retrospective analysis of their experience using desmopressin-stimulated IPSS to determine its diagnostic value for Cushing’s and its predictive value for tumor lateralization.

Researchers analyzed 91 Cushing’s patients who either had negative findings on the MRI imaging of the pituitary or negative high-dose dexamethasone suppression tests, which is another method of evaluation. All patients underwent IPSS with desmopressin, followed by pituitary surgery to extract the tumor.

Of the 91 patients tested, 90 patients had confirmed Cushing’s. And of these, 89 had positive IPSS findings, which led to a sensitivity of 98.9 percent for this test. One patient out of 91 who did not have Cushing’s also underwent this test, which led to a negative IPSS result and a specificity of 100 percent.

Researchers also determined tumor lateralization in patients who were ultimately diagnosed with Cushing’s and underwent surgery. Results of the IPSS showed a 72.5 percent concordance between the results from the IPSS and the surgery.

Therefore, IPSS with desmopressin is a comparable approach to IPSS with CRH for the diagnosis of Cushing’s. It also demonstrates moderate accuracy in determining the location of tumors.

‚ÄúLike many medical centers in China, we currently have no supply of CRH, while desmopressin is readily available,‚ÄĚ researchers concluded. ‚ÄúMoreover, desmopressin is cheaper than CRH. As our data and other studies indicate, IPSS with desmopressin yielded comparable outcomes to IPSS with CRH. Therefore, desmopressin-stimulated IPSS might serve as a possible alternative to CRH-stimulated IPSS.‚ÄĚ

From https://cushingsdiseasenews.com/2017/11/14/ipss-desmopressin-alternative-method-diagnosis-cushings-disease/

A cellular and molecular basis for the selective desmopressin-induced ACTH release in Cushing’s disease patients: key role of AVPR1b receptor and potential therapeutic implications

Journal of Clinical Endocrinology and Metabolism, 07/25/2013¬†‚ÄāReview Article

Luque RM et al. ‚Äď The study aims to determine, for the first time, whether desmopressin acts directly and exclusively on pituitary corticotropinoma cells to stimulate ACTH expression/release, and to elucidate the cellular and molecular mechanisms involved in desmopressin‚Äďinduced ACTH increase in Cushing’s disease (CD).

The present results provide a cellular and molecular basis to support the desmopressin stimulation test as a reliable, specific test for the diagnosis and post‚Äďsurgery prognosis of CD.

Furthermore, the data indicates that AVPR1b is responsible of the direct/exclusive desmopressin‚Äďstimulatory pituitary effects observed in CD, thus opening the possibility of exploring AVPR1b‚Äďantagonists as potential therapeutic tools for CD treatment.

~~~~~~~~

Abstract

  1. RM Luque1,#,
  2. A Ib√°√Īez-Costa1,#,
  3. LM López-Sánchez1,
  4. L Jiménez-Reina2,
  5. E Venegas-Moreno3,
  6. MA G√°lvez4,
  7. A Villa-Osaba1,
  8. AM Madrazo-Atutxa3,
  9. MA Japón5,
  10. A de la Riva6,
  11. DA Cano3,
  12. P Benito-López4,
  13. A Soto-Moreno3,
  14. MD Gahete1,
  15. A Leal-Cerro3,*and
  16. JP Casta√Īo1,*

Author Affiliations


  1. 1Department of Cell Biology, Physiology and Immunology University of Córdoba, Reina Sofía University Hospital, Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC); CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn); 14014, Córdoba, Spain.

  2. 2Department of Morphological Sciences, University of Córdoba. Córdoba, Spain.

  3. 3Instituto de Biomedicina de Sevilla (IBiS), University Hospital Virgen del Rocío/Consejo Superior de Investigaciones Científicas/University of Seville and Endocrinology, Metabolism and Nutrition Unit, Virgen del Rocío University Hospital, Seville, Spain.

  4. 4Service of Endocrinology and Nutrition, Reina Sofía University Hospital, Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC). Córdoba, Spain.

  5. 5Department of Pathology, Virgen del Rocio University Hospital, Seville, Spain.

  6. 6Service of Neurosurgery, Reina Sofía University Hospital Córdoba, Spain.
  1. Address all correspondence and requests for reprints to: Ra√ļl M. Luque and Justo P. Casta√Īo.Department of Cell Biology, Physiology and Immunology; Campus Universitario de Rabanales, Edificio Severo Ochoa (C6), Planta 3; University of C√≥rdoba, E-14014 C√≥rdoba, Spain. Phone:(34)-957218594. Fax:¬†(34)-957218634. E-mails:¬†raul.luque@uco.es;¬†justo@uco.es.
  1. ‚ÜĶ#¬†These authors have codirected this study.

Abstract

Context:¬†Desmopressin is a synthetic agonist of vasopressin-receptors (AVPRs). Desmopressin stimulation test is employed in the diagnosis and post-surgery prognosis of Cushing’s disease (CD). However, the cellular and molecular mechanisms underlying the desmopressin-induced ACTH increase in CD patients are poorly understood.

Objective: 1) To determine, for the first time, whether desmopressin acts directly and exclusively on pituitary corticotropinoma cells to stimulate ACTH expression/release, and 2) to elucidate the cellular and molecular mechanisms involved in desmopressin-induced ACTH increase in CD.

Design: 8 normal-pituitaries (NPs), 23 corticotropinomas, 14 nonfunctioning-pituitary adenomas (NFPA), 17 somatotropinomas and 3 prolactinomas were analyzed for AVPRs-expression by qrtPCR. Primary cultures derived from corticotropinomas, NFPAs, somatotropinomas, prolactinomas and NPs were treated with desmopressin and ACTH-secretion/expression, [Ca2+]i-kinetics, AVPRs-expression and/or proliferative-response were evaluated. The relationship between AVPRs-expression and plasma adrenocorticotropin/cortisol levels obtained from desmopressin-tests was assessed.

Results: Desmopressin affects all functional parameters evaluated in corticotropinoma-cells but not in NPs or other pituitary-adenomas cells. These effects might be due to the dramatic elevation of AVPR1b expression levels found in corticotropinomas. In line with this notion, the use of an AVPR1b-antagonist completely blocked desmopressin-stimulatory effects. Remarkably, only AVPR1b-expression was positively correlated with elevated plasma adrenocorticotropin levels in corticotropinomas.

The present results provide a cellular and molecular basis to support the desmopressin stimulation test as a reliable, specific test for the diagnosis and post-surgery prognosis of CD. Furthermore, our data indicates that AVPR1b is responsible of the direct/exclusive desmopressin-stimulatory pituitary effects observed in CD, thus opening the possibility of exploring AVPR1b-antagonists as potential therapeutic tools for CD treatment.

Footnotes

  • ‚ÜĶ*¬†These authors have codirected this study.

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