Surreptitious diuretic ingestion and pseudo-Bartter's syndrome

Renal fluid and acid/base balance during refeeding in restrictive eating disorders

BACKGROUND AND OBJECTIVES

Fluid shifts have been ascribed to central diabetes insipidus in patients with anorexia nervosa hospitalized for refeeding. Recent data, however, suggest that vasopressin production is not dysregulated in this population. Our objective was to describe the trajectory of fluid imbalances in relationship to kidney function, electrolyte disturbances, and acid/base balance during refeeding.

METHODS

A retrospective review of daily fluid balance and biochemical values was performed in 70 sequential unique patients admitted to University of California at Los Angeles Hospital Medical Stabilization Program for Eating Disorders from December 2018 to November 2020.

RESULTS

Participants (2 males/68 females) were between 10 and 24 years of age and with a median body mass index of 16.1 (14.3, 18.1) kg/m² . A severe negative fluid balance (>-900 ml/day) was observed in 80% of patients at some point during hospitalization. Serum sodium concentrations were normal on admission and remained stable during refeeding. Serum bicarbonate concentrations were 25 ± 1 mEq/dl on admission and increased above the normal range in 31% of patients. Metabolic alkalosis was inversely associated with the development of a negative fluid balance. Estimated glomerular filtration rate was impaired in 54% of patients, improved with refeeding, and was not associated with the development of a severe negative fluid balance or metabolic alkalosis.

DISCUSSION

Chronic energy deprivation alters the physiology of renal fluid and bicarbonate handling in ways that are independent of vasopressin and glomerular filtration. Further studies are warranted to understand the renal adaptations that occur during energy restriction and subsequent refeeding.

PUBLIC SIGNIFICANCE

Massive urinary fluid losses occur in patients with restrictive eating disorders hospitalized for refeeding. In addition, many patients have impaired renal bicarbonate excretion. These findings suggest that chronic energy deprivation impairs the kidney's ability to handle the shifts in fluid and acid/base balance that occur when appropriate oral nutrition is re-introduced.

Bartter syndrome: causes, diagnosis, and treatment

Bartter syndrome is an inherited renal tubular disorder caused by a defective salt reabsorption in the thick ascending limb of loop of Henle, resulting in salt wasting, hypokalemia, and metabolic alkalosis. Mutations of several genes encoding the transporters and channels involved in salt reabsorption in the thick ascending limb cause different types of Bartter syndrome. A poor phenotype-genotype relationship due to the interaction with other cotransporters and different degrees of compensation through alternative pathways is currently reported. However, phenotypic identification still remains the first step to guide the suspicion of Bartter syndrome. Given the rarity of the syndrome, and the lack of genetic characterization in most cases, limited clinical evidence for treatment is available and the therapy is based mainly on the comprehension of renal physiology and relies on the physician's personal experiences. A better understanding of the mutated channels and transporters could possibly generate targets for specific treatment in the future, also encompassing drugs aiming to correct deficiencies in folding or plasma membrane expression of the mutated proteins.

Critical gaps in the medical knowledge base of eating disorders

Eating disorders are unique in that they inherently have much medical comorbidity both as a part of restricting-type eating disorders and those characterized by purging behaviors. Over the last three decades, remarkable progress has been made in the understanding and treatment of the medical complications of eating disorders. Yet, unfortunately, there is much research that is sorely needed to bridge the gap between current medical knowledge and more effective and evidence-based medical treatment knowledge. These gaps exist in many different clinical areas including cardiology, electrolytes, gastrointestinal and bone disease. In this paper, we discuss some of the knowledge gap areas, which if bridged would help develop more effective medical intervention for this population of patients.

Effective medical treatment strategies to help cessation of purging behaviors

OBJECTIVE

Herein we review the major medical issues involved in the "detoxing" of patients who engage in purging behaviors and the pathophysiology of why they occur.

METHODS

Given a limited evidence base of randomized controlled trials, we conducted a thorough qualitative review to identify salient literature with regard to the medical issues involved in "detoxing" patients from their purging behaviors.

RESULTS

Pseudo Bartter's Syndrome is the root cause of much of the medical difficulties which can arise when purging behaviors are abruptly discontinued. However, this is imminently treatable and even preventable with a judicious medical treatment plan which targets the increased serum aldosterone levels which would otherwise promote salt and water retention and a propensity towards severe edema formation. Effective recommendations are provided which can make this process much less vexing for patients attempting to cease their purging behaviors.

CONCLUSIONS

"Detoxing" from purging behaviors can be fraught with medical complications which frustrate these patients and can lead to unsuccessful outcomes. Medical providers should become familiar with the pathophysiology which is the basis for Pseudo Bartter's Syndrome and the effective medical treatments which can lead to a successful outcome.

Electrolyte and acid-base abnormalities associated with purging behaviors

OBJECTIVE

Eating disorders that are associated with purging behaviors are complicated by frequent blood electrolyte and acid-base abnormalities. Herein, we review the major electrolyte and acid-base abnormalities and their treatment methods. The body of rigorous, eating disorder-specific literature on this topical area is not robust enough to perform a systematic review as defined by PRISMA guidelines. Therefore, a qualitative review of mostly medical literature was conducted.

RESULTS

Hypokalemia, hyponatremia, and sodium chloride-responsive metabolic alkalosis are the most common serum changes that occur as a result of purging behaviors. They vary depending on the mode and frequency of purging behaviors. They can all potentially cause dangerous medical complications and are in need of definitive medical treatment.

DISCUSSION

Eating disorders that are associated with purging behaviors are associated with a number of electrolyte and acid-base changes which are complex in their origin, documented to be medically dangerous and this definitive treatment is necessary to help achieve a successful treatment outcome, and in need of definitive treatment as described herein.

Munchausen syndrome and factitious disorder: the role of the laboratory in its detection and diagnosis

The term Munchausen syndrome is used to describe the patient who chronically fabricates or induces illness with the sole intention of assuming the patient role. Such persons often have a close association with the medical profession and thus use their knowledge to falsify symptoms and laboratory specimens to mimic disease. Cases of factitious disease have appeared in the literature originating from all medical specialties, and include such rare disorders as phaeochromocytoma and Bartter's syndrome. The laboratory can play a key role in the detection and diagnosis of factitious disorders. Indeed discrepant biochemistry results may provide the first clue to the diagnosis. Laboratory staff should be particularly aware of highly variable test results and extreme abnormalities that are not consistent with the wider biochemical profile, suggesting sample tampering. Factitious disorder should also be included in the clinician's differential diagnosis when disease presentation is unusual or an underlying cause cannot be found. Investigation to exclude or confirm factitious disorder at an early stage can prevent unnecessary testing in the search for increasingly rare diseases. Appropriate analyses may include screening tests for the detection of surreptitious drug administration or replication of a fabricated sample to confirm the method used. In all cases close communication between the clinician and laboratory is essential. This will ensure that appropriate tests are conducted particularly with regard to time critical and repeat tests.

Drug-induced life-threatening potassium disturbances detected by a pharmacovigilance program from laboratory signals

PURPOSE

Detection and reporting of drug-induced life-threatening potassium disturbances and the study of associated factors under a Pharmacovigilance Program using Laboratory Signals at a Hospital (PPLSH) during a 2-year period.

METHODS

All serum potassium levels <2 mmol/l or >7 mmol/l detected at admission to the hospital, including those of patients who died in the emergency ward or during hospitalization, were monitored prospectively from January 2009 through to December 2010. The incidence rate of each etiology of potassium disturbances was calculated. Factors associated with drug-induced potassium disturbances were detected using a multiple logistic regression model.

RESULTS

The incidence of true life-threatening drug-induced hyper- and hypokalemia events was 3 and 4.32 (Poisson 95 % confidence interval 1.62-10.24), respectively, per 10,000 admissions. Of the severe potassium disturbances, 32.3 % were drug-induced, and 23 % were lethal. We identified previously undescribed pharmacological causes of hyperkalemia (risedronate, doxazosin) and hypokalemia (acyclovir, teicoplanin, cefepime, meropenem, dexketoprofen colistimethate). Significant predictor factors associated with drug-induced hyperkalemia were the use of polypharmacy (>5 drugs), age (>74 years), sex (female) and kidney disease (glomerular filtration rate <60 ml/min) with the presence of ≥4 comorbid conditions. The only predictor of drug-induced hypokalemia was the use of >5 drugs. The triggering factor associated with drug-induced hyperkalemia and hypokalemia was azotemia and hypoalbuminemia, respectively.

CONCLUSIONS

Drug-induced life-threatening potassium disturbances remain a relevant problem. Potential strategies for prevention are to avoid polypharmacy, early discontinuation of treatment of drugs causing hyperkalemia or nephrotoxicity in cases of various clinical situations (cardiac descompensation, infection, hypovolemia) or obstructive causes, and insistence on albumin control during hospitalization.

Successful "detoxing" from commonly utilized modes of purging in bulimia nervosa

Bulimia nervosa has many medical complications associated with the different modes of purging utilized by these patients. There also are inherent medical complications associated with chronic purging when these behaviors are abruptly discontinued. These complications experienced by a patient with bulimia nervosa when they decide to cease purging, can be a strong deterrent to successfully treating this disorder. Therefore it behooves care providers to become familiar with these complications in order to skillfully recommend strategies to help overcome the tendency to revert to purging behaviors.

PseudoBartter syndrome in eating disorders

OBJECTIVE

PseudoBartter's syndrome, a complex pattern of seemingly unrelated metabolic abnormalities, is frequently seen in patients with eating disorders, particularly those who indulge in purging behaviors. We present two cases that, despite divergent background histories and clinical presentations, possess the unifying pathophysiology that ultimately leads to this syndrome.

METHOD

Case report and review of literature pertaining to Bartter's and PseudoBartter's syndromes.

RESULTS

Purging behaviors commonly result in a state of profound dehydration and chloride depletion that leads to the metabolic abnormalities characteristic of inheritable sodium and chloride renal tubular transport disorders. In the eating disorder patient, these abnormalities lead to a propensity towards marked edema formation.

DISCUSSION

The metabolic and clinical manifestations of PseudoBartter's syndrome are seen more commonly than previously thought. It is important to appreciate that a complex self-perpetuating pathophysiology leads to the hypokalemic metabolic alkalosis characteristic of PseudoBartter syndrome. The metabolic abnormalities characteristic of this phenomenon should therefore be viewed in this context and the resulting predilection towards marked edema formation should be borne in mind.

Analyses of subjects with hypokalemic metabolic alkolosis, Gitelman's and Bartter's syndrome

The two most common forms of inherited normotensive hypokalemic metabolic alkalosis are Bartter's and Gitelman's syndromes. Bartter's is mostly seen in children, while Gittelman's is mostly seen in adolescents and adults. We analyze three subjects of adult-onset Gitelman's and Bartter's syndrome. The patients applied to our hospital due to severe hypokalemia with little clinical expression (paresthesia, cramp, polyuria, polydipsia, and/or weakness). All had normal blood pressure, hypokalemia, hyperreninemic hyperaldosteronism, and a decrease in the fractional chloride reabsorption. Key elements in differential diagnosis of chronic hypokalemia are blood pressure assessment, acid base equilibrium, serum calcium concentration, and 24-hour urine potassium and calcium excretion.

Encephalopathy after furosemide use in nephrotic syndrome

An 18-year-old girl with nephrotic syndrome presented with a life-threatening respiratory failure and a severe encephalopathy, shortly after being started on furosemide. The evaluation confirmed furosemide as the sole culprit for the clinical manifestations. This case highlights an unpredictable dose-response relationship of furosemide. The pathophysiological basis, differential diagnosis and clinical implications of the observed findings are discussed.

Acquired Bartter-Like Syndrome Associated with Gentamicin Administration

Although acute nonoliguric renal failure is a well-known nephrotoxic effect of aminoglycoside antibiotics, less recognized is acquired Bartter-like syndrome. Herein, we describe four female patients who presented with marked paresthesia, muscle weakness, and tetany following gentamicin therapy with total dose ranging from 1.2 g to 2.6 g. All were normotensive. Biochemical abnormalities included hypokalemia (K+ 1.8-2.3 mmol/L), metabolic alkalosis (HCO(3-) 31.9-34.2 mmol/L), hypomagnesemia (Mg2+ 0.9-1.2 mg/dL), hypermagnesiuria (fractional excretion of Mg 3-6%), hypocalcemia (free Ca2+ 2.0-4.1 mg/dL), and hypercalciuria (molar ratio of Ca2+/creatinine 0.23-0.53), all consistent with Bartter-like syndrome. Serum immunoreactive parathyroid hormone concentration was low despite the hypocalcemia. The Bartter-like syndrome lasted for 2 to 6 weeks after cessation of gentamicin, coupled with supplementation of K+, Ca2+, and Mg2+. These biochemical abnormalities resembled those seen in patients with gain-of-function mutations in the calcium-sensing receptor. We hypothesize that gentamicin, a polyvalent cationic molecule, induces the action of calcium-sensing receptor on the thick ascending loop of Henle and distal convoluted tubule to cause renal wasting of Na+, K+, Cl-, Ca2+, and Mg2+.

Primer on clinical acid-base problem solving

Acid-base problem solving has been an integral part of medical practice in recent generations. Diseases discovered in the last 30-plus years, for example, Bartter syndrome and Gitelman syndrome, D-lactic acidosis, and bulimia nervosa, can be diagnosed according to characteristic acid-base findings. Accuracy in acid-base problem solving is a direct result of a reproducible, systematic approach to arterial pH, partial pressure of carbon dioxide, bicarbonate concentration, and electrolytes. The 'Rules of Five' is one tool that enables clinicians to determine the cause of simple and complex disorders, even triple acid-base disturbances, with consistency. In addition, other electrolyte abnormalities that accompany acid-base disorders, such as hypokalemia, can be incorporated into algorithms that complement the Rules and contribute to efficient problem solving in a wide variety of diseases. Recently urine electrolytes have also assisted clinicians in further characterizing select disturbances. Acid-base patterns, in many ways, can serve as a 'common diagnostic pathway' shared by all subspecialties in medicine. From infectious disease (eg, lactic acidemia with highly active antiviral therapy therapy) through endocrinology (eg, Conn's syndrome, high urine chloride alkalemia) to the interface between primary care and psychiatry (eg, bulimia nervosa with multiple potential acid-base disturbances), acid-base problem solving is the key to unlocking otherwise unrelated diagnoses. Inasmuch as the Rules are clinical tools, they are applied throughout this monograph to diverse pathologic conditions typical in contemporary practice.

Inherited primary renal tubular hypokalemic alkalosis: a review of Gitelman and Bartter syndromes

Inherited hypokalemic metabolic alkalosis, or Bartter syndrome, comprises several closely related disorders of renal tubular electrolyte transport. Recent advances in the field of molecular genetics have demonstrated that there are four genetically distinct abnormalities, which result from mutations in renal electrolyte transporters and channels. Neonatal Bartter syndrome affects neonates and is characterized by polyhydramnios, premature delivery, severe electrolyte derangements, growth retardation, and hypercalciuria leading to nephrocalcinosis. It may be caused by a mutation in the gene encoding the Na-K-2Cl cotransporter (NKCC2) or the outwardly rectifying potassium channel (ROMK), a regulator of NKCC2. Classic Bartter syndrome is due to a mutation in the gene encoding the chloride channel (CLCNKB), also a regulator of NKCC2, and typically presents in infancy or early childhood with failure to thrive. Nephrocalcinosis is typically absent despite hypercalciuria. The hypocalciuric, hypomagnesemic variant of Bartter syndrome (Gitelman syndrome), presents in early adulthood with predominantly musculoskeletal symptoms and is due to mutations in the gene encoding the Na-Cl cotransporter (NCCT). Even though our understanding of these disorders has been greatly advanced by these discoveries, the pathophysiology remains to be completely defined. Genotype-phenotype correlations among the four disorders are quite variable and continue to be studied. A comprehensive review of Bartter and Gitelman syndromes will be provided here.

Gitelman's syndrome: an overlooked cause of chronic hypokalemia and hypomagnesemia in adults

In 1966, Gitelman described a benign variant of classical Bartter's syndrome in adults characterized by consistent hypomagnesemia and hypocalciuria, hypokalemic metabolic alkalosis and hyperreninemic hyperaldosteronism with normal blood pressure. A specific gene has been found responsible for this disorder, encoding the thiazide-sensitve Na-Cl coporter (TSC) in the distal convoluted tubule. Mutant alleles result in loss of normal TSC function and the phenotype is identical to patients with chronic use of thiazide diuretics. Gitelman's syndrome is a more common cause of chronic hypokalemia than Bartter's syndrome, with which it is often confused. The distinguishing features between both syndromes are discussed.

Syndrome of hypokalemic metabolic alkalosis and hypomagnesemia associated with gentamicin therapy: case reports

Nephrotoxicity, as evidenced by renal insufficiency is a well-known consequence of gentamicin therapy. We report two patients with gentamicin-induced syndrome of hypokalemic metabolic alkalosis and hypomagnesemia. Both had complete recovery of renal tubular function after cessation of antibiotic therapy. These cases emphasize the need to routinely monitor patients receiving gentamicin therapy for electrolyte abnormalities to avoid potential morbidity.

Acid-base disorders in medicine

The practice of internal medicine involves daily exposure to abnormalities of acid-base balance. A wide variety of disease states either predispose patients to develop these conditions or lead to the use of medications that alter renal, gastrointestinal, or pulmonary function and secondarily alter acid-base balance. In addition, primary acid-base disease follows specific forms of renal tubular dysfunction (renal tubular acidosis). We review the acid-base physiologic functions of the kidney and gastrointestinal tract and the current understanding of acid-base pathophysiologic conditions. This includes a review of whole animal and renal tubular physiologic characteristics and a discussion of the current knowledge of the molecular biology of acid-base transport. We stress an approach to diagnosis that relies on knowledge of acid-base physiologic function, and we include discussion of the appropriate treatment of each disorder considered. Finally, we include a discussion of the effects of acidosis and alkalosis on human physiologic functions.

Urinary chloride excretion distinguishes between renal and extrarenal metabolic alkalosis

The aetiology of normotensive hypokalaemic metabolic alkalosis is sometimes not obtainable from the history. Observations in adults indicate that the urinary chloride excretion is low in metabolic alkalosis of extrarenal origin. The chloride/creatinine ratio in random urines was therefore compared in 283 healthy children and in eight paediatric patients with metabolic alkalosis. The urinary chloride/creatinine ratio was reduced in four patients with metabolic alkalosis of extrarenal origin and within reference values or above in four patients with metabolic alkalosis of renal origin.

CONCLUSION

The study confirms that urinary chloride/creatinine ratio discriminates between extrarenal and renal forms of metabolic alkalosis.

Bartter's syndrome: the unsolved puzzle

Bartter's syndrome is a congenital abnormality characterized by metabolic alkalosis [corrected], hyperreninemic hyperaldosteronism, and hypokalemia. Most patients present early in life with symptoms such as muscle weakness and polyuria, which may be attributed to potassium depletion. Despite the hyperaldosteronism, the patients tend to be normotensive, which is at least partially explained by vascular hyporesponsiveness to pressor hormones. Numerous studies have documented increased renal excretion of prostaglandins. Several different patterns of aberrant renal ion transport have been observed in patients with the syndrome, suggesting that it actually may represent a family of related but distinct tubular disorders. Therapeutic approaches to Bartter's syndrome include potassium supplementation, prostaglandin synthesis inhibitors (nonsteroidal anti-inflammatory agents), aldosterone antagonists, and converting enzyme inhibitors. During the first two decades following its initial description, Bartter's syndrome was the focus of widespread interest, based on the likelihood that its investigation might provide insight into the normal functioning of the renin-angiotensin-aldosterone and prostanoid hormone systems. During the past decade, however, little additional progress has been made in Bartter's syndrome, and its patho-physiology remains poorly understood.

Diseases of renal adenosine triphosphatase

Most renal transport is a primary or secondary result of the action of one of three membrane bound ion translocating ATPase pumps. The proximal tubule mechanisms for the reabsorption of salt, volume, organic compounds, phosphate, and most bicarbonate reabsorption depend upon the generation and maintenance of a low intracellular sodium concentration by the basolateral membrane Na-K-ATPase pump. The reabsorption of fluid and salt in the loop of Henle is similarly dependent on the energy provided by Na-K-ATPase activity. Some proximal tubule bicarbonate reabsorption and all distal nephron proton excretion is a product of one of two proton translocating ATPase pumps, either an electrogenic H-ATPase or an electroneutral H-K-ATPase. In this article, the authors review the biochemistry and physiology of pump activity and consider the pathophysiology of proximal and distal renal tubular acidosis, the Fanconi syndrome, and Bartter's syndrome as disorders of ATPase pump function.

A case of pseudo-Bartter's syndrome due to intestinal malrotation

Intestinal malrotation presenting beyond the neonatal period is associated with a multiplicity of symptoms, which are often non-specific and, consequently, are associated with delays in diagnosis. Pseudo-Bartter's syndrome, which mimics the manifestations of Bartter's syndrome, can be caused by a severe chloride deficiency secondary to vomiting, diarrhea, perspiration, diuretic abuse and so on. We describe a 6 year old boy who had been admitted to hospital three times during the preceding year. The patient lapsed into a critical condition with profound hypochloremia and hypokalemic metabolic alkalosis induced by extremely massive vomiting. The attacks of vomiting were spasmodic and self-limited. During the episodes of vomiting he fulfilled the criteria of pseudo-Bartter's syndrome, including hyperreninemia, hyperaldosteronism and normal blood pressure, but in the intervals between attacks he was completely asymptomatic. At the third admission, examination supported an overall clinical picture of bowel obstruction, which was confirmed by radiographic examination. Laparotomy revealed a midgut volvulus with intestinal malrotation. After surgery he made a good recovery and was symptom-free. In this patient, the high degree of hypochloremia and hypovolemia activated the renin-angiotensin-aldosterone system, then aldosterone promoted intensive reabsorption of sodium and excretion of potassium into the urine. Consequently the diagnosis of pseudo-Bartter's syndrome was establish on the basis of an extreme decrease in urinary chloride and an increase in urinary potassium concentration. It is relatively rare for vomiting due to intestinal malrotation to induce pseudo-Bartter's syndrome. The importance of considering this rare diagnosis in such cases is discussed.

[Recurrent metabolic encephalopathy, self-administered gastric lavage and Munchausen syndrome]

A case report of recurrent metabolic encephalopathy with disorders of hydro-electrolytic balance, predominantly severe hypochloremic alkalosis, resulting from self-induced vomiting and self-administered gastric tubage and lavage. Munchausen syndrome was diagnosed. Some established characteristics of this syndrome as well as some atypical features concerning patient-doctor relationship and natural history are discussed.

Marked reduction of Tamm-Horsfall protein synthesis in hyperprostaglandin E-syndrome

Hyperprostaglandin E-syndrome (HPS), a recently described variant of Bartter's syndrome (BS), resembles BS in a number of symptoms but is distinct from BS in others. Similar to BS, HPS is characterized by congenital hypokalemic alkalosis, hypertrophy of the juxtaglomerular apparatus, hyperreninemia, secondary hyperaldosteronism, normal blood pressure and renal diabetes insipidus. Other than BS, HPS is constantly associated with chronic hypercalciuria and nephrocalcinosis as well as both renal and systemic PGE2 overproduction. Correction of most of the symptoms in HPS is achieved by permanent inhibition of prostaglandin synthesis with indomethacin. Among the causes leading to HPS, a selective damage of the distal tubule in HPS has been suggested. Therefore, synthesis of Tamm-Horsfall protein (THP), a glycoprotein exclusively produced in the thick ascending limb of the loop of Henle, was measured by ELISA in the urine of seven infant HPS patients (aged 3 to 8 years). Patients were investigated both under constant indomethacin treatment and after a one week period without indomethacin. Nine healthy children (aged 5 months to 10 years) served as controls. In controls mean daily THP excretion was 54.2 +/- 13.9 (median 46.0) mg/24 hr/1.73 m2 whereas in HPS, THP levels were strongly diminished. During withdrawal of indomethacin treatment, mean THP level was 12.7 +/- 10.1 (median 7.2) mg/24 hr/1.73 m2 and 10.3 +/- 10.1 (median 3.5) mg/24 hr/1.73 m2 under indomethacin treatment, respectively. THP excretion values both without indomethacin and under indomethacin treatment were significantly different from controls (P < or = 0.005); however, there was no significant difference between the THP levels during or after cessation of indomethacin treatment. Creatinine clearance in HPS patients was 75.1 +/- 15.9 (median 76.2) ml/min/1.73 m2 without indomethacin and 81.9 +/- 15.1 (median 83.0) ml/min/1.73 m2 under indomethacin treatment. Control values were not obtained. Comparative measurements of THP excretion in six classical BS-patients (aged 3 months to 17 years) revealed normal THP values in two individuals and intermediate levels in the others: the mean level of six BS patients was 30.8 +/- 13.5 (median 25.0) mg/24 hr/1.73 m2 and was thus significantly higher than in HPS both with and without indomethacin treatment (P < or = 0.05). Immunohistochemistry in renal biopsies of three of the HPS patients showed a strong reduction of cortical tubular THP immunoreactivity in two cases and a less pronounced reduction in the third. In situ hybridization using a THP-riboprobe in these three biopsies revealed significantly reduced or absent THP-mRNA levels.(ABSTRACT TRUNCATED AT 400 WORDS)

Adaptation to severe chronic hypokalemia in anorexia nervosa: a plea for conservative management

Severe hypokalemia may constitute a life-threatening medical emergency. In the group of purging eating disorder patients, potassium blood levels tend to be chronically low while physical signs and symptoms may be absent. Nevertheless, these patients are frequently subjected to vigorous supportive treatment and often an aggressive diagnostic workup. We present a chronic purging anorexia nervosa patient in whom potassium blood levels reach a low of 1.6 mmol/L in the absence of physical symptoms. Purging eating disorder patients adapt to chronic hypokalemia. We believe the clinical/medical approach to this electrolyte disturbance in chronic eating disorder patients should be different from the approach to patients suffering from acute hypokalemia.

Medical complications of anorexia nervosa and bulimia nervosa

The internist plays a critical role in the care of eating disorder patients, especially in the management of the life-threatening medical complications of these conditions. In anorexia nervosa, the immediate danger is related to the effects of voluntary starvation, including hypophosphatemia, bone marrow failure, cardiac decompensation, and shock. Patients with bulimia nervosa more often experience severe fluid and electrolyte abnormalities resulting in hypovolemia, secondary hyperaldosteronism, depletion of total body potassium, and cardiac arrhythmias. Immediate management of medical complication and correction of nutritional deficits are necessary before patients can benefit from psychotherapy. The need for continued involvement of the internist in the ongoing care of the eating disorder patient is stressed. The high mortality and the likelihood of chronicity without early intervention underscore the need for early recognition and skilled management of eating disorders.

Exogenous prostaglandin administration and pseudo-Bartter syndrome

Biological abnormalities simulating Bartter syndrome were observed in a preterm neonate with complex cyanotic congenital heart disease, for which ductus arteriosus was maintained open by high doses of prostaglandin (PG) until a Blalock shunt could be performed. These abnormalities spontaneously disappeared after cessation of PG administration. We postulate that the natriuretic effect of exogenous administered PG could further increase sodium wasting already induced by the cardiopathy thus leading to pseudo-Bartter syndrome.

[Secondary gout and pseudo-Bartter syndrome in females with laxative abuse]

Four females (27-54 y), presenting with a history of long-term laxative abuse, were admitted to the Medizinische Poliklinik for evaluation of generalized weakness. Laboratory findings revealed signs of Bartter's syndrome, including hypokalemia, systemic alkalosis and normal blood pressure. Three of the four females showed impaired renal function and elevated serum uric acid levels, two of them suffered from recurrent gouty attacks. In our patients the incidence of hyperuricemia and impaired renal function, as a consequence of chronic hypokalemia, was much higher than known from patients with Bartter's syndrome. Hyperuricemia is related to some pathophysiological features of Pseudo-Bartter's syndrome, (e.g. systemic alkalosis, elevated angiotensin) and combined with additional factors (e.g. catabolism, reduced plasma volume) may lead to gouty attacks. Gallstones were found in two of the four females. Long term surreptitious laxative ingestion frequently is observed in females. Hypokalemia, induced by the laxatives, causes reduced intestinal motility and leads to augmented laxative intake. These patients are prone to develop Pseudo-Bartter's syndrome, causing eventually a hyperuricemia and gouty attacks.

Disorders of mineralocorticoid activity

The investigation of syndromes of mineralocorticoid excess and deficiency has been reviewed. For screening for primary aldosteronism, repeated measures of plasma potassium on high sodium intake is the most practicable method. Further investigation should include saline infusion and, in cases of doubt, fludrocortisone/sodium loading. Differential diagnosis of adenoma from hyperplasia is best achieved by the aldosterone response to posture, CT scanning and, if necessary, adrenal venous catheterization. Suitable techniques for the investigation of secondary aldosteronism of unknown cause and for primary and secondary hypoaldosteronism are described, as well as the adjustment of dosage for replacement therapy where mineralocorticoid secretion is deficient.

[Factitious diseases and Münchausen's syndrome]

Factitious diseases in which the symptoms are simulated or created intentionally are very varied: functional manifestations, haemorrhages, anaemia, pyrexia, metabolic disturbances (hypoglycaemia, hypokalaemia, hyperthyroidism, etc.), skin lesions and others. Different symptomatic associations are possible. The Munchausen syndrome which is mainly seen in anglo-saxon countries, is characterised by a long history of factitious symptoms in subjects with psychological profiles which are difficult to define because of the very behaviour of the patients themselves. Besides this syndrome, many psychological disorders have been described in patients presenting with factitious symptoms. One particular form is the creation of factitious diseases in children by their parents. The diagnosis of factitious disease is always difficult and confirmatory proof cannot always be obtained apart from certain cases in which laboratory tests show the presence of drugs in the plasma or urine. Psychotherapy which appears to be essential for these patients is generally very difficult to achieve.