Protein-losing enteropathy after Fontan operation

Long-term Issues After the Fontan Procedure

The Fontan procedure is used to treat various serious congenital heart defects. Although many people who have had the procedure live productively into adulthood, as they age, they face several health issues due to the physiology of the Fontan circulation. This article reviews the 4 types of Fontan procedures and the changes caused by the surgery, including single-ventricle physiology, nonpulsatile pulmonary perfusion, systemic venous hypertension, and intracardiac scarring, as well as their sequelae. Key nursing assessment items and possible treatment strategies are reviewed. Additional topics, including pregnancy in patients who have undergone the procedure, infective endocarditis prophylaxis, and health-related quality of life, are briefly discussed. Options for Fontan failure, including Fontan conversion or transplantation, are presented. Potential future solutions are outlined.

Low total, low-density lipoprotein, high-density lipoprotein, and non-high-density lipoprotein cholesterol levels in patients with complex congenital heart disease after Fontan palliation

OBJECTIVE

To test the hypothesis that patients with complex congenital heart disease who have undergone Fontan palliation have low total cholesterol, low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) levels.

STUDY DESIGN

We retrospectively reviewed the random serum lipid profiles obtained at cardiology clinic visits between May 2010 and November 2011 in patients who had undergone the Fontan procedure. We compared these serum lipid levels against age- and sex-matched established normal data from the Third National Health and Nutrition Examination Survey.

RESULTS

Eighty-eight patients who had undergone the Fontan procedure also had laboratory test data obtained during their visits. Median total cholesterol level in the Fontan group was 127 mg/dL (IQR, 116-144 mg/dL), median HDL-C was 40 mg/dL (IQR, 33-45 mg/dL), median non-HDL-C was 86 mg/dL (IQR, 76-109 mg/dL), and median LDL-C was 66 mg/dL (IQR, 57-83 mg/dL). Total cholesterol, LDL-C, non-HDL-C, and HDL-C levels were significantly lower in patients who had undergone a Fontan procedure compared with age- and sex-matched normal individuals (mean z-score, -1.4, -1.2, -1.0, and -1.0 respectively; all P<.0001). Cholesterol levels were below the 25th percentile for age and sex for total cholesterol in 82% of patients, for LDL-C in 76%, for non-HDL-C in 67%, and for HDL-C in 57%.

CONCLUSION

Patients who have undergone the Fontan procedure have significantly lower serum total cholesterol, LDL-C, HDL-C and non-HDL-C levels than age- and sex-matched normal individuals. Although the implications of this finding are unknown, it raises the possibility of abnormalities in cholesterol absorption, synthesis, or catabolism in this patient population.

Orthotopic heart transplantation in patients with univentricular physiology

Parallel advancements in surgical technique, preoperative and postoperative care, as well as a better understanding of physiology in patients with duct-dependent pulmonary or systemic circulation and a functional single ventricle, have led to superb results in staged palliation of most complex congenital heart disease (CHD) [1]. The Fontan procedure and its technical modifications have resulted in markedly improved outcomes of patients with single ventricle anatomy [2,3,4]. The improved early survival has led to an exponential increase of the proportion of Fontan patients surviving long into adolescence and young adulthood [5]. Improved early and late survival has not yet abolished late mortality secondary to myocardial failure, therefore increasing the referrals for cardiac transplantation [6]. Interstage attrition [7] is moreover expected in staged palliation towards completion of a Fontan-type circulation, while Fontan failure represents a growing indication for heart transplantation [8]. Heart transplantation has therefore become the potential “fourth stage” [9] or a possible alternative to a high-risk Fontan operation [10] in a strategy of staged palliation for single ventricle physiology. Heart transplant barely accounts for 16% of pediatric solid organ transplants [11]. The thirteenth official pediatric heart transplantation report- 2010 [11] indicates that pediatric recipients received only 12.5% of the total reported heart transplants worldwide. Congenital heart disease is not only the most common recipient diagnosis, but also the most powerful predictor of 1-year mortality after OHT. Results of orthotopic heart transplantations (OHT) for failing single ventricle physiology are mixed. Some authors advocate excellent early and mid-term survival after OHT for failing Fontan [9], while others suggest that rescue-OHT after failing Fontan seems unwarranted [10]. Moreover, OHT outcome appears to be different according to the surgical staging towards the Fontan operation and surgical technique of Fontan completion [12].

The focus of this report is a complete review of the recent literature on OHT for failing single ventricles, outlining the clinical issues affecting Fontan failure, OHT listing and OHT outcome. These data are endorsed reporting our experience with OHT for failing single ventricle physiology in recent years.

Children with protein-losing enteropathy after the Fontan operation are at risk for abnormal bone mineral density

Protein-losing enteropathy (PLE) is a rare but potentially devastating complication of single-ventricle physiology after the Fontan operation. Although abnormal bone mineral density (BMD) is a known complication of chronic disease and congenital heart disease, no reports have described BMD in patients with PLE. This study investigated a cross-sectional sample of children and young adults with a confirmed diagnosis of PLE. Serum levels of 25(OH)D, calcium, total protein, and albumin were recorded from the first outpatient encounter with each subject. Corrected calcium (cCa) was calculated from the serum calcium and albumin levels. Dual-energy X-ray absorptiometry (DXA) was used to measure BMD, and z-scores were generated using appropriate software. DXA results were available for 12 patients (eight males and four females). The age at DXA ranged from 7.2 to 25.2 years. The mean z-score was -1.73 standard deviation (SD) for the entire cohort, with 42 % z-scores below -2 SDs. Serum 25(OH)D levels were abnormal in 58 % of the patients. There was a positive correlation between cCa and DXA z-score and a negative correlation between total protein and DXA z-score. Patients receiving corticosteroid therapy had a significantly lower DXA z-score than those not receiving corticosteroids (-3.15 vs. -0.31; p = 0.02). Children with PLE are at risk for abnormal BMD compared with age- and sex-matched control subjects. In the study cohort, corticosteroid exposure, a marker of disease severity, appeared to be associated with decreased BMD. Routine bone health screening is warranted for children with PLE, particularly those receiving corticosteroid therapy.

Protein-losing enteropathy and the Fontan operation

Protein-losing enteropathy (PLE) is a complex disorder characterized by enteric protein loss and often is associated with cardiovascular abnormalities, particularly those with elevated central venous pressure. The Fontan operation is a surgical procedure used to palliate patients with a functional single ventricle. Although the Fontan operation eliminates cyanosis and decreases the workload of the functionally single ventricle, it also elevates central venous pressure. This can result in hepatic and enteric congestion as well as PLE. Despite the universal elevation in central venous pressure, only a fraction of patients who have had a Fontan operation develop PLE. However, PLE is associated with significant morbidity and mortality. Presenting signs and symptoms of PLE include abdominal bloating, diarrhea, edema, pleural effusions, ascites, and failure to thrive. In this review, the authors discuss the diagnosis and prevalence of PLE after the Fontan operation and review currently available therapeutic strategies.

Extracardiac complications of the Fontan circuit

The Fontan operation is the primary surgical procedure used in the palliation of patients with univentricular cardiac physiology. With improved survival of children with congenital heart disease, long-term complications of the Fontan circuit are being encountered more frequently. Radiologists are more likely to see both the cardiac and extracardiac complications of the Fontan circuit. Awareness of the common extracardiac complications in children with failing Fontan circuits will aid the radiologist in making the appropriate diagnosis and guide the cardiologist caring for these patients.

Hypoplastic left heart syndrome: current considerations and expectations

In the recent era, no congenital heart defect has undergone a more dramatic change in diagnostic approach, management, and outcomes than hypoplastic left heart syndrome (HLHS). During this time, survival to the age of 5 years (including Fontan) has ranged from 50% to 69%, but current expectations are that 70% of newborns born today with HLHS may reach adulthood. Although the 3-stage treatment approach to HLHS is now well founded, there is significant variation among centers. In this white paper, we present the current state of the art in our understanding and treatment of HLHS during the stages of care: 1) pre-Stage I: fetal and neonatal assessment and management; 2) Stage I: perioperative care, interstage monitoring, and management strategies; 3) Stage II: surgeries; 4) Stage III: Fontan surgery; and 5) long-term follow-up. Issues surrounding the genetics of HLHS, developmental outcomes, and quality of life are addressed in addition to the many other considerations for caring for this group of complex patients.

The precarious state of the liver after a Fontan operation: summary of a multidisciplinary symposium

As the cohort of survivors with the single-ventricle type of congenital heart disease grows, it becomes increasingly evident that the state of chronically elevated venous pressure and decreased cardiac output inherent in the Fontan circulation provides the substrate for a progressive decline in functional status. One organ at great risk is the liver. Wedged between two capillary beds, with the pulmonary venous bed downstream, which typically has no pulsatile energy added in the absence of a functional right ventricle, and the splanchnic bed upstream, which may have compromised inflow due to inherent cardiac output restriction characteristic of the Fontan circulation, the liver exists in a precarious state. This review summarizes a consensus view achieved at a multidisciplinary symposium held at The Children's Hospital of Philadelphia in June 2011. The discussion includes current knowledge concerning the hemodynamic foundations of liver problems, the diagnostic tools available, the unique histopathology of the liver after the Fontan operation, and proposed mechanisms for hepatic fibrosis at the cellular level. At the completion of the symposium, a consensus recommendation was made by the authors' group to pursue a new prospective protocol for clinical evaluation of the liver for all patients in our practice 10 years after the Fontan operation.

New concepts: development of a survivorship programme for patients with a functionally univentricular heart

Children with functionally univentricular hearts are now surviving into their third and fourth decades of life. Although survival alone is a remarkable achievement, a lot must still be done to improve the quality and duration of life after the Fontan operation. Challenges that may be faced by these patients include the impact of the Fontan operation on the liver and the density of bone, protein-losing enteropathy, and plastic bronchitis. Paediatric cardiologists are familiar with the haemodynamic issues inherent in Fontan physiology; however, training in cardiology is often not sufficient to give us a complete understanding of the pathophysiology of the complications or of the options for treatment. Collaboration with other subspecialists including gastroenterologists, endocrinologists, and pulmonologists is essential in order to provide the rigorous and nuanced care that our patients need and deserve. A clinic in which a patient can see multiple subspecialists, and in which the subspecialists, as a group, can discuss each patient, can provide a unique and valuable service for patients with a functionally univentricular heart.

Late catheter interventions in hypoplastic left heart syndrome

Interventional cardiology plays a key role in the diagnosis and management of patients with functionally univentricular physiology after the various stages of surgical palliation. The interventions performed are widely variable in type, including angioplasty of stenotic vessels and implantation of stents in stenotic vessels; closure of defects such as collaterals, leaks in baffles, and fenestrations; creation of fenestration; and more. In the setting of venous hypertension associated with stenosis at the Fontan baffle, conduit, or pulmonary arteries, stent implantation is often preferred, as the aim is to eliminate completely the narrowing, given that relatively mild stenosis can have a significant detrimental hemodynamic effect in patients with functionally univentricular circulation. The procedure is highly successful. In patients who fail after Fontan procedure, creation of a fenestration is often performed, with variable technique depending on the underlying anatomic substrate. To increase chances of patency of the fenestration, implantation of a stent is often required, particularly in the setting of an extracardiac conduit. For those patients with cyanosis and favorable Fontan hemodynamics, closure of the fenestration is performed using atrial septal occluder devices with high success rate. Coils compatible with magnetic resonance imaging are used widely to treat collateral vessels, although on occasion other specific embolization tools are required, such as particles or vascular plugs. Postoperative arch obstruction is successfully managed with angioplasty at a younger age, while implantation of a stent in the aorta is reserved for older patients. Specifics of these interventional procedures as applied to the population of patients with functionally univentricular hearts are described in this manuscript.

Oral budesonide as a therapy for protein-losing enteropathy in patients having undergone Fontan palliation

BACKGROUND

  Protein-losing enteropathy is associated with Fontan palliation for single-ventricle physiology and has been difficult to treat. Limited data suggest the successful use of oral budesonide (Entocort, AstraZeneca) as a palliative measure.

METHODS

  We examine our single-institution retrospective experience in eight patients who were treated with this therapy.

RESULTS

  Median pretherapy albumin level was 1.7 g/dL (range 1.0-2.7 g/dL), 3 months after therapy was 3.1 g/dL (range 2-4.8 g/dL), and by the end of the first year was 3.4 g/dL (range 2.1-5.3 g/dL). All patients had at least a transient improvement, and at latest follow-up (median 29 months, range 3-51 months) five patients remain on therapy. Five of eight patients had required pretherapy albumin transfusions; one patient required albumin infusions after therapy. Four patients had side effects associated with the medication.

CONCLUSIONS

  Oral budesonide is an additional therapy that has the potential to improve symptoms and delay need for heart transplantation in this patient population.

The failing Fontan: etiology, diagnosis and management

While the Fontan operation has facilitated the survival of a generation of children born with congenital heart disease resulting in a functional single ventricle, it does not recreate a normal circulation. Over time, survivors of the Fontan operation are at risk for ventricular dysfunction, plastic bronchitis, protein-losing enteropathy and chronic Fontan failure. New techniques and therapies are emerging to address the long-term risks associated with Fontan physiology, but as the number of survivors continues to grow, the recognition of the limitations of this circulation is increasing. Novel investigations of possible mechanical devices designed to function as a subpulmonary ventricle are underway, but are still many years away from clinical use. In the meantime, continued development of medical therapeutics targeted at the specific problems of the Fontan circulation will be beneficial and might reduce the need for cardiac transplantation.

Oral budesonide treatment for protein-losing enteropathy in Fontan-palliated patients

Protein-losing enteropathy (PLE) is a rare complication of Fontan palliation associated with significant morbidity and mortality. It is characterized by the loss of serum proteins into the intestinal lumen, and its pathophysiology likely involves enteral inflammation. Budesonide, an oral steroid, is an attractive treatment option because of its potent enteral activity and minimal systemic side effects. A single-center, retrospective review of Fontan-palliated PLE patients treated with oral budesonide for 6 months or longer was performed. The patient characteristics reviewed were demographics, anatomic diagnosis, budesonide treatment (dose and duration), other medications and therapeutic interventions, hospitalizations, serum albumin levels, medical complications, and patient status at the time of follow-up assessment. The study enrolled 10 patients representing 228 patient-months of on-therapy follow-up evaluation. Serum albumin levels increased after initiation of budesonide for 90% of the patients, and clinical evidence of fluid overload improved for 60% of them. Symptomatic improvement was reported in 80% of the cases. During the treatment period, 50% of the patients met the primary end point of death or cardiac transplantation. In this series of PLE patients, oral budesonide therapy was associated with significant symptomatic improvement and sustained increases in serum albumin. However, budesonide therapy may not alter the long-term outcome for patients with advanced PLE.

Staged single-ventricle palliation in 2011: outcomes and expectations

Outcomes for staged palliation for single-ventricle heart disease have improved over the past two decades. As outcomes improve, parental expectations for survival and quality of life have risen accordingly. Nevertheless, the number of interventions and complications these patients must endure remain high. The final surgical destination of the single-ventricle patient, the total cavopulmonary connection (or Fontan operation) successfully separates systemic venous and pulmonary venous blood flow but does so at great cost. Fontan patients remain at significant risk of complications despite what are perceived to be "favorable" hemodynamics. The outcomes in this population are discussed in this review, with particular attention to the history behind our current strategies as well as to recent salient studies.

Gastrointestinal lymphatics in health and disease

Lymphatics perform essential transport and immune regulatory functions to maintain homeostasis in the gastrointestinal (GI) system. Although blood and lymphatic vessels function as parallel and integrated systems, our understanding of lymphatic structure, regulation and functioning lags far behind that of the blood vascular system. This chapter reviews lymphatic flow, differences in lymphangiogenic and hemangiogenic factors, lymphatic fate determinants and structural features, and examines how altered molecular signaling influences lymphatic function in organs of the GI system. Innate errors in lymphatic development frequently disturb GI functioning and physiology. Expansion of lymphatics, a prominent feature of GI inflammation, may also play an important role in tissue restitution following injury. Destruction or dysregulation of lymphatics, following injury, surgery or chronic inflammation also exacerbates GI disease activity. Understanding the physiological roles played by GI lymphatics is essential to elucidating their underlying contributions to forms of congenital and acquired forms of GI pathology, and will provide novel approaches for therapy.

Living with complex congenital heart disease

A child with complex congenital heart disease in 2008 is very likely to survive a series of surgical and medical interventions, and confront an array of medical and psychosocial stressors that are presently poorly understood. As approaches to medical problems change, careful assessment of those results is essential, and the initial work of the multicentre Pediatric Heart Network is a huge step in the right direction, setting the stage for proper controlled trials of therapies. Major complications, notably ventricular failure, rhythm problems and thromboembolism, will affect nearly one-quarter of survivors, necessitating further interventions. Appropriate educational and psychosocial support for these children and their families is the next challenge for all of us in the field of paediatrics. How ironic would it be to have invested so much in early survival, only to allow the child to fail in life itself.

Rare problems associated with the Fontan circulation

The Fontan operation, originally described for the surgical management of tricuspid atresia, is now the final surgery in the strategy of staged palliation for a number of different forms of congenital cardiac disease with a functionally univentricular heart. Despite the improved technical outcomes of the Fontan operation, staged palliation does not recreate a normal physiology. Without a pumping chamber delivering blood to the lungs, the cardiovascular system is less efficient; cardiac output is generally diminished, and the systemic venous pressure is increased. As a result, patients with "Fontan physiology" may face a number of rare but potentially life-threatening complications including hepatic dysfunction, abnormalities of coagulation, protein-losing enteropathy, and plastic bronchitis. Despite the staged palliation resulting in remarkable survival, the possible complications for this group of patients are complex, involve multiple organ systems, and can be life threatening. Identifying the mechanisms associated with each of the rare complications, and developing strategies to treat them, requires the work of many people at many institutions. Continued collaboration between sub-specialists and between institutions will be required to optimise the care for this group of survivors with functionally univentricular hearts.

Causes and consequences of lymphatic disease

The visceral manifestations of lymphatic disorders (lymphangiomatosis and lymphangiectasia) are particularly severe. Any pathology of the lymphatic vasculature, whether superficial or internal, regional, or systemic, is predominated by the appearance of lymphedema, the characteristic form of tissue edema that occurs when lymphatic dysfunction supervenes. Disease manifestations may include dysregulation of body fluid homeostasis, immune traffic impairment, and disturbances of lipid and protein reabsorption from the gut lumen. The appearance of lymphatic edema invokes complex biological alterations. Many of these changes seem to relate uniquely to chronic lymphatic edema, including a profound stimulus to collagen and adipose deposition. Despite the recent advances in our understanding of these disorders, substantial knowledge gaps remain; these gaps inhibit our ability to accurately identify, categorize, treat, and prevent these diseases. Future diagnostic, therapeutic, and reproductive decisions for affected individuals require an accurate knowledge of the clinical and laboratory presentation, mode of inheritance, treatment response, outcomes, and prognosis.

Sildenafil in the management of the failing Fontan circulation

BACKGROUND

Sildenafil is increasingly being used in the management of pulmonary arterial hypertension in the newborn. Its role in patients with congenital cardiac disease is less well defined and as yet has only been reported sporadically.

AIM

Present our experience with sildenafil treatment in patients with a failing Fontan circulation.

PATIENTS AND METHODS

Retrospective review of 13 symptomatic patients after Fontan palliation who received treatment with sildenafil between January, 2006 and July, 2008.

RESULTS

Three patients suffered from protein-losing enteropathy, four patients presented with bronchial casts, two had severe cyanosis after fenestrated Fontan procedure, two had prolonged chylous effusions, one had a previous failure of Fontan and take-down, and one patient had arrhythmias and end-stage cardiac failure requiring conversion to an extra-cardiac Fontan. Sildenafil was used in the dosage of 1-2 milligrams per kilogram 3-4 times per day. Protein-losing enteropathy and alpha-1-antitrypsin levels improved in all three patients on sildenafil treatment. One of these patients had a concomitant catheter creation of a fenestration, as did two patients presenting with bronchial casts and both patients with persistent chylous effusions. All four patients with bronchial casts and two patients with cyanosis improved significantly on sildenafil treatment. Chylous effusions decreased after sildenafil and stent enlargement of a fenestration. There were no significant side effects requiring sildenafil withdrawal over a treatment period ranging from 2 months to 2 years.

CONCLUSIONS

Sildenafil can be used safely and effectively in the treatment of patients with a failing Fontan circulation.

Canadian Cardiovascular Society 2009 Consensus Conference on the management of adults with congenital heart disease: complex congenital cardiac lesions

With advances in pediatric cardiology and cardiac surgery, the population of adults with congenital heart disease (CHD) has increased. In the current era, there are more adults with CHD than children. This population has many unique issues and needs. They have distinctive forms of heart failure and their cardiac disease can be associated with pulmonary hypertension, thromboemboli, complex arrhythmias and sudden death. Medical aspects that need to be considered relate to the long-term and multisystemic effects of single ventricle physiology, cyanosis, systemic right ventricles, complex intracardiac baffles and failing subpulmonary right ventricles. Since the 2001 Canadian Cardiovascular Society Consensus Conference report on the management of adults with CHD, there have been significant advances in the field of adult CHD. Therefore, new clinical guidelines have been written by Canadian adult CHD physicians in collaboration with an international panel of experts in the field. Part III of the guidelines includes recommendations for the care of patients with complete transposition of the great arteries, congenitally corrected transposition of the great arteries, Fontan operations and single ventricles, Eisenmenger's syndrome, and cyanotic heart disease. Topics addressed include genetics, clinical outcomes, recommended diagnostic workup, surgical and interventional options, treatment of arrhythmias, assessment of pregnancy risk and follow-up requirements. The complete document consists of four manuscripts, which are published online in the present issue of The Canadian Journal of Cardiology. The complete document and references can also be found at www.ccs.ca or www.cachnet.org.

(111)Indium-transferrin for localization and quantification of gastrointestinal protein loss

OBJECTIVE

To evaluate the indium-111 ((111)In)-transferrin method as a means of localization and quantification of gastrointestinal protein loss.

METHODS

Fourteen patients and 15 healthy subjects underwent an (111)In-transferrin study consisting of abdominal scintigraphy, whole-body counting measurement and determination of plasma activity of (111)In during the course of 5 days. Two of the patients went through a subsequent chromium-51-trichloride test with analysis of radioactivity in faeces in order to compare the results of the two methods.

RESULTS

The patients had a mean +/-SEM whole-body loss of (111)In of 10.9+/-2.9% for 96 h, while the healthy controls lost 1.8+/-1.3% (p=0.0045). The decay in plasma activity followed biexponential kinetics. The characteristic plasma transit time was 5.0+/-1.0 h in patients and 12.1+/-1.5 h in controls (p=0.0007). Scintigraphically, patients had obvious abdominal foci of activity, while the control subjects showed diffuse activity. Anatomic localization of the leaking spot seemed more uncertain. By comparison with the (51)CrCl(3) test, the loss of radio-labelled protein appeared to be in the same order of magnitude.

CONCLUSIONS

Quantification of gastrointestinal protein loss can be done without collecting faeces. Normal subjects have a loss of a few per cent, making the (111)In-transferrin method comparable with the former standard using (51)CrCl(3). Plasma measurements of (111)In are not predictive of the magnitude of the loss. Scintigraphic localization of the site of the loss needs to be optimized, for instance by serial imaging or image fusion with an anatomical modality.

The Fontan/Kreutzer procedure at 40: an operation for the correction of tricuspid atresia

The first atriopulmonary anastomosis (APA) with neither a valve in the inferior vena cava (IVC) nor an Glenn shunt was performed in 1971. A fenestration was intentionally left in the atrial septum. In a second patient, the APA incorporated the patient's own pulmonary valve, which had been removed from the outflow tract of the right ventricle. Since the early days, our rationale was that the right atrium would only function as a pathway, and the end diastolic pressure and the systole of the main ventricle would be the principal "pump" of this system. The late hemodynamic problems of the APA have decreased with newer and better surgical techniques, such as the lateral tunnel (LT) or the extracardiac conduit (EC). Although these procedures have improved the prognosis and quality of life of patients with a univentricular heart (UH), in the long run, deterioration frequently occurs because of chronic low cardiac output and high central venous pressure. Progressive increase in pulmonary vascular resistances and ventricular dysfunction are frequently the underlying reasons for this deterioration. However, such deterioration is not inevitable in every case, as shown in the longest survivor of the world after 34 years of follow-up. The Fontan Kreutzer (FK) palliation represents the best surgical option despite its uncertain late outcome. Certainly, it is one of the triumphs of cardiac surgery in congenital heart disease.

Protein-losing enteropathy: case illustrations and clinical review

Protein-losing enteropathy (PLE) is a rare syndrome of gastrointestinal protein loss that may complicate a variety of diseases. The primary causes can be divided into erosive gastrointestinal disorders, nonerosive gastrointestinal disorders, and disorders involving increased central venous pressure or mesenteric lymphatic obstruction. The diagnosis of PLE should be considered in patients with hypoproteinemia after other causes, such as malnutrition, proteinuria, and impaired protein synthesis due to cirrhosis, have been excluded. The diagnosis of PLE is most commonly based on the determination of fecal alpha-1 antitrypsin clearance. Treatment of PLE targets the underlying disease but also includes dietary modification, supportive care, and maintenance of nutritional status. In this article, cases illustrating a variety of clinical presentations and etiologies of PLE are presented, and its diagnostic approach and treatment are reviewed.

Disorders of intestinal secretion and absorption

The gastrointestinal tract possesses a huge epithelial surface area and performs many different tasks. Amongst them are the digestive and absorptive functions. Disorders of intestinal absorption and secretion comprise a variety of different diseases, e.g. coeliac disease, lactase deficiency or Whipple's disease. In principle, impaired small intestinal function can occur with or without morphological alterations of the intestinal mucosa. Therefore, in the work up of a malabsorptive syndrome an early small intestinal biopsy is encouraged in conjunction with breath tests and stool analysis to guide further management. In addition, there is an array of functional tests, the clinical availability of which becomes more and more limited. In any case, early diagnosis of the underlying pathophysiology is most important, in order to initiate proper therapy. In this chapter, diagnostic procedure of malabsorption is discussed with special attention to specific disease like coeliac disease, Whipple's disease, giardiasis and short bowel syndrome. Furthermore, bacterial overgrowth, carbohydrate malabsorption and specific nutrient malabsorption (e.g. for iron or vitamins) and protein-losing enteropathy are presented with obligatory and optional tests as used in the clinical setting.