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Free access

Evidence against a role of human airway trypsin-like protease – the human analogue of the growth-promoting rat adrenal secretory protease – in adrenal tumourigenesis

Stefanie Hahner, Martin Fassnacht, Fabian Hammer, Markus Schammann, Dirk Weismann, Immo Alex Hansen, and Bruno Allolio

Objective: A serine protease from rat adrenal cortex was recently characterized and named adrenal secretory protease (AsP). AsP is expressed in the adrenal cortex and is capable of cleaving pro-γ-melanocyte-stimulating hormone (1-76 N-terminus of pro-opiomelanocortin) into fragments that act as adrenal mitogens. AsP may therefore play a crucial role in adrenal growth and tumourigenesis. The aim of this study was to further characterize the human homologue of AsP and its possible role in adrenal tumourigenesis.

Methods and results: Starting with the rat cDNA sequence of AsP we detected high homology to the catalytic C-terminus of the human airway trypsin-like protease (HAT). Further analysis revealed that the HAT gene is the human homologue of a long splice variant of AsP, which we recently described as rat airway trypsin-like serine protease 1. In contrast to rodents, no short isoform of HAT was found in humans due to a stop codon in exon 6 which prevents the expression of a short isoform. While high expression of HAT mRNA was found in the trachea and in the gastrointestinal tract, expression in the adrenal was only very weak. RT-PCR and real-time PCR analysis revealed a complex tissue expression pattern of HAT, indicating a role for this protease in multiple tissues. We further investigated HAT expression in five normal adrenal glands, 15 adrenocortical adenomas (five hormonally inactive adenomas, five aldosterone-producing adenomas and five cortisol-producing adenomas), nine adrenocortical carcinomas, five phaeochromocytomas and two adrenal hyperplasias. Weak HAT expression was detectable in only two out of five normal adrenal glands, in one out of twenty-four adrenocortical tumours and four out of five phaeochromocytomas. However, the expression in the adrenal tissue was several orders of magnitude lower than in the trachea. In addition, we could not detect any HAT transcripts in a sample of fetal adrenal.

Conclusion: Gene structure and tissue distribution of HAT, the human homologue of the rat adrenal secretory protease AsP, reveal major interspecies differences. The observation of very low expression levels in normal adrenal tissue and adrenocortical tumours casts doubt about a role for HAT in the physiological and pathological growth of adrenocortical cells.

Free access

Life-threatening events in patients with pheochromocytoma

Anna Riester, Dirk Weismann, Marcus Quinkler, Urs D Lichtenauer, Sandra Sommerey, Roland Halbritter, Randolph Penning, Christine Spitzweg, Jochen Schopohl, Felix Beuschlein, and Martin Reincke

Objective

Pheochromocytomas are rare chromaffin cell-derived tumors causing paroxysmal episodes of headache, palpitation, sweating and hypertension. Life-threatening complications have been described in case reports and small series. Systematic analyses are not available. We took an opportunity of a large series to make a survey.

Design and methods

We analyzed records of patients diagnosed with pheochromocytomas in three geographically spread German referral centers between 2003 and 2012 (n=135).

Results

Eleven percent of the patients (ten women, five men) required in-hospital treatment on intensive care units (ICUs) due to complications caused by unsuspected pheochromocytomas. The main reasons for ICU admission were acute catecholamine induced Tako-Tsubo cardiomyopathy (n=4), myocardial infarction (n=2), acute pulmonary edema (n=2), cerebrovascular stroke (n=2), ischemic ileus (n=1), acute renal failure (n=2), and multi organ failure (n=1). One patient required extracorporeal membrane oxygenation due to a hypertensive crisis with lung edema occurring during delivery (n=1). Two patients died of refractory shock and pheochromocytomas were found postmortem. Two patients were treated by emergency surgery. Compared to pheochromocytoma patients without life-threatening events (n=120), patients with complications had a significant larger maximal tumor diameter (7.0 vs 4.5 cm, P<0.01), higher levels of catecholamines (20- vs ninefold upper limit of normal, P<0.01), and tended to be younger (42 vs 51 years, P=0.05).

Conclusion

Although pheochromocytomas are rare, they are likely to be associated with a life-threatening situation. Clinicians have to be aware of these situations and perform a timely diagnosis.

Open access

Treatment of symptomatic hyponatremia with hypertonic saline: a real-life observational study

Irina Chifu, Amelie Gerstl, Björn Lengenfelder, Dominik Schmitt, Nils Nagler, Martin Fassnacht, and Dirk Weismann

Objective

Treatment of symptomatic hyponatremia is not well established. The European guidelines recommend bolus-wise administration of 150 mL of 3% hypertonic saline. This recommendation is, however, based on low level of evidence.

Design

Observational study.

Methods

Sixty-two consecutive hyponatremic patients admitted to the emergency department or intensive care unit of the University Hospital Wuerzburg were divided in subgroups according to treatment (150 mL bolus of 3% hypertonic saline or conventional treatment) and symptom severity. Treatment target was defined as an increase in serum sodium by 5–10 mEq/L within first 24 h and maximum 8 mEq/L during subsequent 24 h.

Results

Thirty-three out of sixty-two patients (53%) were presented with moderate symptoms and 29/62 (47%) with severe symptoms. Thirty-six were treated with hypertonic saline and 26 conventionally. In the hypertonic saline group, serum sodium increased from 116 ± 7 to 123 ± 6 (24 h) and 127 ± 6 mEq/L (48 h) and from 121 ± 6 to 126 ± 5 and 129 ± 4 mEq/L in the conventional group, respectively. Overcorrection at 24 h occurred more frequent in patients with severe symptoms than with moderate symptoms (38% vs 6%, P < 0.05). Diuresis correlated positively with the degree of sodium overcorrection at 24 h (r = 0.6, P < 0.01). Conventional therapies exposed patients to higher degrees of sodium fluctuations and an increased risk for insufficient sodium correction at 24 h compared to hypertonic saline (RR: 2.8, 95% CI: 1.4–5.5).

Conclusion

Sodium increase was more constant with hypertonic saline, but overcorrection rate was high, especially in severely symptomatic patients. Reducing bolus-volume and reevaluation before repeating bolus infusion might prevent overcorrection. Symptoms caused by hypovolemia can be misinterpreted as severely symptomatic hyponatremia and diuresis should be monitored.

Free access

Measurements of plasma metanephrines by immunoassay vs liquid chromatography with tandem mass spectrometry for diagnosis of pheochromocytoma

Dirk Weismann, Mirko Peitzsch, Anna Raida, Aleksander Prejbisz, Maria Gosk, Anna Riester, Holger S Willenberg, Reiner Klemm, Georg Manz, Timo Deutschbein, Matthias Kroiss, Roland Därr, Martin Bidlingmaier, Andrzej Januszewicz, Graeme Eisenhofer, and Martin Fassnacht

Background

Reports conflict concerning measurements of plasma metanephrines (MNs) for diagnosis of pheochromocytomas/paragangliomas (PPGLs) by immunoassays compared with other methods. We aimed to compare the performance of a commercially available enzyme-linked immunoassay (EIA) kit with liquid chromatography–tandem mass spectrometric (LC–MS/MS) measurements of MNs to diagnose PPGLs.

Methods

In a substudy of a prospective, multicenter trial to study the biochemical profiles of monoamine-producing tumors, we included 341 patients (174 males and 167 females) with suspected PPGLs (median age 54 years), of whom 54 had confirmed PPGLs. Plasma MNs were measured by EIA and LC–MS/MS, each in a specialized laboratory.

Results

Plasma normetanephrine (NMN) and MN were measured 60 and 39% lower by EIA than by LC–MS/MS. Using upper cut-offs stipulated for the EIA, diagnostic sensitivity was only 74.1% at a specificity of 99.3%. In contrast, use of similar cut-offs for MN and overall lower age-adjusted cut-offs for NMN measured by LC–MS/MS returned a diagnostic sensitivity and specificity of 98.1 and 99.7%. Areas under receiver-operating characteristic curves, nevertheless, indicated comparable diagnostic performance of the EIA (0.993) and LC–MS/MS (0.985). Diagnostic sensitivity for the EIA increased to 96.2% with a minimal loss in specificity (95.1%) following use of cut-offs for the EIA adapted to correct for the negative bias.

Conclusions

The EIA underestimates plasma MNs and diagnostic sensitivity is poor using commonly stipulated cut-offs, resulting in a high risk for missing patients with PPGLs. Correction of this shortcoming can be achieved by appropriately determined cut-offs resulting in comparable diagnostic performance of EIA and LC–MS/MS assays.

Free access

Metabolic impact of pheochromocytoma/paraganglioma: targeted metabolomics in patients before and after tumor removal

Zoran Erlic, Max Kurlbaum, Timo Deutschbein, Svenja Nölting, Aleksander Prejbisz, Henri Timmers, Susan Richter, Cornelia Prehn, Dirk Weismann, Jerzy Adamski, Andrzej Januszewicz, Martin Reincke, Martin Fassnacht, Mercedes Robledo, Graeme Eisenhofer, Felix Beuschlein, and Matthias Kroiss

Objective

Excess catecholamine release by pheochromocytomas and paragangliomas (PPGL) leads to characteristic clinical features and increased morbidity and mortality. The influence of PPGLs on metabolism is ill described but may impact diagnosis and management. The objective of this study was to systematically and quantitatively study PPGL-induced metabolic changes at a systems level.

Design

Targeted metabolomics by liquid chromatography-tandem mass spectrometry of plasma specimens in a clinically well-characterized prospective cohort study.

Methods

Analyses of metabolic profiles of plasma specimens from 56 prospectively enrolled and clinically well-characterized patients (23 males, 33 females) with catecholamine-producing PPGL before and after surgery, as well as measurement of 24-h urinary catecholamine using LC-MS/MS.

Results

From 127 analyzed metabolites, 15 were identified with significant changes before and after surgery: five amino acids/biogenic amines (creatinine, histidine, ornithine, sarcosine, tyrosine) and one glycerophospholipid (PCaeC34:2) with increased concentrations and six glycerophospholipids (PCaaC38:1, PCaaC42:0, PCaeC40:2, PCaeC42:5, PCaeC44:5, PCaeC44:6), two sphingomyelins (SMC24:1, SMC26:1) and hexose with decreased levels after surgery. Patients with a noradrenergic tumor phenotype had more pronounced alterations compared to those with an adrenergic tumor phenotype. Weak, but significant correlations for 8 of these 15 metabolites with total urine catecholamine levels were identified.

Conclusions

This first large prospective metabolomics analysis of PPGL patients demonstrates broad metabolic consequences of catecholamine excess. Robust impact on lipid and amino acid metabolism may contribute to increased morbidity of PPGL patients.