Fat digestion and absorption: Normal physiology and pathophysiology of malabsorption, including diagnostic testing

Fat digestion and absorption play crucial roles in maintaining energy homeostasis and supporting essential physiological functions. The initial stage of fat digestion occurs in the stomach, where gastric lipase begins the hydrolysis of triglycerides. However, most fat digestion takes place in the small intestine via pancreatic enzymes and bile salts. Emulsification of fat by bile acids facilitates enzymatic action, breaking down triglycerides into free fatty acids and monoglycerides, which are then able to be absorbed by enterocytes. Fat malabsorption can result from various underlying conditions, such as exocrine pancreatic insufficiency, bile acid disorders, or intestinal diseases. The clinical manifestations of fat malabsorption include steatorrhea, malnutrition, and deficiencies of fat-soluble vitamins. Diagnostic approaches involve assessing fecal fat levels, imaging studies, and various functional tests to identify the specific etiology. This review article will describe the normal physiologic process of fat digestion and absorption and discuss various pathophysiology that can lead to fat malabsorption within the gastrointestinal tract as well as their respective diagnostic testing modalities. Effective digestion of fat is essential for overall health, because it allows for absorption of many essential nutrients, plays an integral role in cellular and structural function, and supplies energy to the body. When this is dysfunctional, disorders of malabsorption can occur. This article will give a brief overview of the physiologic process of fat digestion and absorption in healthy individuals as well as review important pathophysiology that can lead to fat malabsorption within the gastrointestinal tract and current diagnostic testing modalities.

A life-threatening presentation of postgastrectomy exocrine pancreatic insufficiency: A case report

Key Clinical Message

Physicians must be alert for the exocrine pancreatic insufficiency diagnosis through the follow-up of postgastrectomy patients, regardless the severity and lag time. Urgent albumin and pancreatic enzyme replacement should be considered when diagnosed.

Abstract

It is documented that exocrine pancreatic insufficiency (EPI) can develop after gastrectomy. Steatorrhea, malnutrition, and weight loss are common symptoms of the disease; however, it is usually mild to moderate postgastrectomy. This article reports a case of EPI manifested by hypoalbuminemia leading to dyspnea and anasarca, which are not typical symptoms of postgastrectomy EPI. A 61-year-old man with a history of gastric adenocarcinoma treated by total gastrectomy and chemoradiotherapy was admitted to the hospital with dyspnea and anasarca. Despite being diagnosed as a case of malignancy recurrence in another hospital, based on the symptoms described, no evidence of malignancy was found. His ascites and pleural effusion were determined to be caused by hypoalbuminemia. In addition, he claimed steatorrhea, and his stool elastase was lower than expected. EPI was diagnosed based on his medical history, paraclinical tests, and examinations. He remained asymptomatic for 1 year after being treated with albumin and pancreatic enzymes. Postgastrectomy EPI may be severe enough to cause steatorrhea or hypoalbuminemia. Hence, regardless of the severity of the presentation, physicians must be alert for this diagnosis throughout the follow-up of patients with a history of gastrectomy. Urgent albumin and pancreatic enzyme replacement should be considered when diagnosed.

Risk factor analysis and nomogram development for steatorrhea in idiopathic chronic pancreatitis

OBJECTIVES

Steatorrhea, a sign of severe pancreatic exocrine insufficiency (PEI), is related to consequences caused by pancreatitis. This study aimed to identify predictors and to construct a nomogram for steatorrhea in idiopathic chronic pancreatitis (ICP).

METHODS

ICP patients admitted to our hospital from January 2000 to December 2013 were enrolled in this retrospective-prospective cohort study and randomly assigned to the training and validation cohorts. The cumulative rate of steatorrhea was calculated. A Cox proportional hazard regression model was used to identify predictors for steatorrhea and construct the nomogram. Internal and external validation of the nomogram was then performed.

RESULTS

There were 1633 ICP patients enrolled, with a median follow-up duration of 9.8 years and 20.8% (339/1633) of patients developed steatorrhea following onset of ICP. Steatorrhea was observed in 93, 115, and 133 patients at 1, 3, and 5 years following diagnosis of CP, with a cumulative rate of 6.5% (95% confidence interval [CI] 5.1%-7.9%), 8.0% (95% CI 6.2%-9.8%), and 9.3% (95% CI 6.6%-12.0%), respectively. Male sex (hazard ratio [HR] 2.479, P < 0.001), diabetes mellitus at/before diagnosis of ICP (HR 2.274, P = 0.003), and aged less than 18 years at onset of ICP (HR 0.095, P < 0.001) were identified risk factors for steatorrhea. Initial manifestations were associated with development of steatorrhea. The nomogram was proven to have good concordance indexes.

CONCLUSIONS

We identified predictors and developed a nomogram for predicting steatorrhea in ICP. It was recommended that high-risk populations be followed up closely, which might contribute to the early diagnosis and treatment of PEI.

Pathophysiology and Management of Hyperoxaluria and Oxalate Nephropathy: A Review

Hyperoxaluria results from either inherited disorders of glyoxylate metabolism leading to hepatic oxalate overproduction (primary hyperoxaluria), or increased intestinal oxalate absorption (secondary hyperoxaluria). Hyperoxaluria may lead to urinary supersaturation of calcium oxalate and crystal formation, causing urolithiasis and deposition of calcium oxalate crystals in the kidney parenchyma, a condition termed oxalate nephropathy. Considerable progress has been made in the understanding of pathophysiological mechanisms leading to hyperoxaluria and oxalate nephropathy, whose diagnosis is frequently delayed and prognosis too often poor. Fortunately, novel promising targeted therapeutic approaches are on the horizon in patients with primary hyperoxaluria. Patients with secondary hyperoxaluria frequently have long-standing hyperoxaluria-enabling conditions, a fact suggesting the role of triggers of acute kidney injury such as dehydration. Current standard of care in these patients includes management of the underlying cause, high fluid intake, and use of calcium supplements. Overall, prompt recognition of hyperoxaluria and associated oxalate nephropathy is crucial because optimal management may improve outcomes.

Shwachman-Diamond Syndrome in a Child Presenting With Chronic Diarrhea: A Rare Case in Family Medicine Practice

Diarrhea remains an important cause of morbidity and mortality worldwide. Chronic diarrhea often represents a diagnostic challenge for family medicine and pediatric physicians because of its broad spectrum of possible etiologies. The differential diagnoses can be narrowed by taking a detailed history and performing an appropriate physical examination. In general, chronic diarrhea can be due to osmotic, secretory, inflammatory, or dysmotility-related pathologies. We present the case of a 30-month-old male who was brought to the family medicine clinic with a complaint of abdominal bloating and persistent diarrhea after every feeding for four months. His stools were foul-smelling and occurred more than four times a day. The patient was below the second standard deviations for weight and height. He appeared pale, and there was no scleral icterus. The patient underwent upper endoscopy, which showed no abnormal gross findings. A dedicated abdominal computed tomography scan was performed to evaluate the pancreas for any structural abnormalities. The scan demonstrated complete replacement of the pancreatic parenchyma by fatty tissue. The diagnosis of Shwachman-Diamond syndrome was established as the analysis revealed a mutation in the SBDS gene. The patient was treated with pancreatic enzyme replacement therapy. After two months of follow-up, the parents reported that the patient had significant improvement in diarrhea. Shwachman-Diamond syndrome is a very rare inherited disorder characterized by bone marrow failure, exocrine pancreatic dysfunction, and skeletal abnormalities. Despite its rarity, clinicians should keep a high index for this condition when they encounter a child with unexplained chronic diarrhea.

Cystic fibrosis and coeliac disease: a case report of an unusual association

Coeliac disease (CD) and cystic fibrosis (CF) are well known as the most common causes of chronic intestinal malabsorption in childhood. The coexistence of coeliac disease with cystic fibrosis is uncommon. Here, we describe the case of cystic fibrosis in a patient diagnosed with coeliac disease who failed to respond clinically to a gluten-free diet and had persistent steatorrhea and failure to thrive.

Post-Acute Pancreatitis Pancreatic Exocrine Insufficiency: Rationale and Methodology of a Prospective, Observational, Multicenter Cohort Study

OBJECTIVES

We describe the methodology of Post-Acute Pancreatitis Pancreatic Exocrine Insufficiency (PAPPEI), a prospective, observational, multicenter cohort study. The objectives of PAPPEI are to estimate the incidence rate of post-acute pancreatitis (AP) pancreatic exocrine insufficiency (PEI), define factors that determine the development of post-AP PEI, and evaluate the impact of post-AP PEI on nutritional status and quality of life.

METHODS

Enrollment started in June 2017 in 3 expert academic centers in the United States. Data were collected during hospitalization (baseline) at 3 and 12 months after enrollment. Fecal elastase-1 was used to assess PEI. Study questionnaires are completed by patient interview and review of electronic medical records. Blood is obtained to evaluate vitamin deficiencies and nutritional markers.

RESULTS

As of August 2020, 77 subjects have completed the baseline evaluation. The median age was 58 years (interquartile range, 39-67 years), 38% were male, and 90% were white. The etiology of AP was biliary in 39 subjects (51%), and 51 subjects (66%) had mild AP. Three- and 12-month follow-up data have been collected in 29 and 13 subjects, respectively.

CONCLUSION

The PAPPEI study aims to expand our understanding of post-AP PEI incidence, including its impact on nutritional status and quality of life.

Steatorrhea Versus Normal Stool in Neonatal and Early Infantile Period: Implications for Biliary Atresia

Physicochemical property of undigested milk fat is theoretically analyzed. With uniqueness of neonatal/early infantile period and fat amount, the highest estimated stiffness of stool is gel or paste level. Therefore, typical stool of breastfed, small amount either watery or "seedy" is incompatible with steatorrhea, which may be useful to diagnose biliary atresia patients.

Etiologies, Clinical Features, and Outcome of Oxalate Nephropathy

Background

Oxalate nephropathy is a potentially underestimated cause of kidney failure characterized by massive deposition of calcium oxalate crystals in the renal parenchyma. The prevalence and modes of presentation of this entity are ill-defined.

Methods

Here we report on the largest consecutive series of cases of adult oxalate nephropathy diagnosed on native kidney biopsies from January 2010 to December 2018 in the UCLouvain Kidney Disease Network.

Results

We screened 2265 native kidney biopsies and identified 22 cases (1%) of oxalate nephropathy. Patients had a mean age at diagnosis of 61 years (±20) and presented either with acute on chronic kidney disease (CKD) (62%) or with acute kidney injury (AKI) (38%). Mean serum creatinine at biopsy was 8.0 ± 4.5 mg/dl. Kidney biopsies showed abundant calcium oxalate crystal deposits, associated with acute interstitial nephritis and tubular necrosis, and variable degrees of interstitial fibrosis and tubular atrophy. Chronic pancreatitis and gastric bypass were the most common causes of oxalate nephropathy (48%). During a mean follow-up of 29 months, half of the patients (52%) progressed to kidney failure, all within the month following diagnosis. Higher serum creatinine level at presentation and interstitial fibrosis and tubular atrophy score were associated with progression to kidney failure.

Conclusion

Oxalate nephropathy is the cause of kidney disease in 1% of consecutive native kidney biopsies and typically presents as acute on CKD or AKI. The prognosis of the disease is poor, with a high rate of kidney failure within the first month after the diagnosis.

Chylomicron Retention Disease in A Male Infant: A Rare Case from Pakistan

Chylomicron retention disease (CMRD), also known as Anderson's disease, is an autosomal recessive condition with a genetic mutation in the secretion associated Ras related GTPase 1B (SAR1B) gene, a protein coding gene. CMRD classically manifests as steatorrhea, vomiting, failure to thrive or abdominal bloating shortly after birth or in childhood. Here, we report a rare case of a 50-day-old male infant who was, at first, overseen as a case of acute gastroenteritis with sepsis owing to the non-specific symptoms i.e. multiple episodes of loose stools with a low-grade fever and failure to thrive, and was managed accordingly. However, the symptoms did not resolve; moreover, the clinical condition deteriorated. Later, lipid profile, clinical presentation and pathological features led to a presumptive diagnosis of CMRD. Our patient showed significant improvement when treated with a trial of medium- and short-chain fatty acids. We conclude that, in resource-restricted countries, a therapeutic trial with the dietary changes is essential to not only prevent the devastating complication but also support the diagnosis.

Bruising as the first sign of exocrine pancreatic insufficiency in infancy

Exocrine pancreatic insufficiency is an important cause of chronic malnutrition, secondary to maldigestion-malabsorption, which can be caused in children especially by cystic fibrosis, but also by other much rarer diseases. The case of a 6 months and 3 weeks old male pediatric patient is reported, who was admitted to the clinic for head and forearms bruising. Laboratory findings identified vitamin K deficiency as the cause of the cutaneous hemorrhagic syndrome. Further investigations revealed association of steatorrhea (which is a marker of fat malabsorption), iron-deficiency anemia and hypovitaminosis D, which had been produced by nutritional deficiencies caused by malabsorption syndrome. From the numerous disorders that could be associated with pancreatic insufficiency in children, the following conditions had been excluded: cystic fibrosis (mucoviscidosis), cow's milk protein intolerance, gluten-sensitive enteropathy (coeliac disease), Shwachman-Diamond syndrome, abetalipoproteinemia, etc. Based upon decreased levels of stool pancreatic elastase in repeated measurements, together with low serum lipase, the final diagnosis of exocrine pancreatic insufficiency was established. Treatment of this case consisted mainly in pancreatic enzyme replacement therapy, but also oral iron supplementation and dietary supplements with fat-soluble vitamins (A, D, E, K). The outcome was favorable, characterized by normalization of intestinal passage, ascending growth curve and normalization of the majority of laboratory tests values that were modified between the time of patient admission to our clinic and initiation of specific therapy (serum level of vitamin K, vitamin D and lipase, coagulation profile, hemoglobin and red blood cell indexes), as well as higher value of fecal pancreatic elastase.

Use of an In-line Digestive Cartridge With Enteral Nutrition Improves the Weight Trajectory of 2 Children With Cystic Fibrosis Complicated by Another Medical Diagnosis

This clinical observation describes the enteral nutrition (EN) management of 2 toddlers at high nutrition risk due to cystic fibrosis (CF), exocrine pancreatic insufficiency, and comorbid medical conditions. The first case report describes a boy with severe malabsorption after intestinal resection. The second case report reviews a boy with CF and neuroblastoma. When pancreatic enzyme replacement therapy with EN was not effective or appropriate, use of an in-line digestive cartridge was initiated. While using the digestive cartridge, both children showed improvements in their anthropometric measures. This observation reviews the nutrition management throughout their clinical course and describes the use of a digestive cartridge with EN.

Nutrition and Inflammatory Biomarkers in Chronic Pancreatitis Patients

BACKGROUND

Chronic pancreatitis (CP) patients frequently experience malabsorption and maldigestion, leading to micronutrient and macronutrient deficiencies. Comorbid diabetes and lifestyle habits, such as alcohol consumption, may impact nutrition status.

METHODS

We compared micronutrient antioxidant, bone metabolism, serum protein, and inflammatory marker levels in 301 CP patients and 266 controls with no known pancreatic disease. We analyzed serum prealbumin and retinol binding protein; vitamins A, D, E, and B12; osteocalcin; tumor necrosis factor-α; and C-reactive protein (CRP). We also evaluated biomarkers among subsets of patients, examining factors including time since diagnosis, body mass index, alcohol as primary etiology, diabetes mellitus, vitamin supplementation, and pancreatic enzyme replacement.

RESULTS

After correcting for multiple comparisons, CP patients had significantly lower levels than controls of the following: vitamin A (40.9 vs 45.4 μg/dL) and vitamin E (α-tocopherol [8.7 vs 10.3 mg/L] and γ-tocopherol [1.8 vs 2.2 mg/L]), as well as osteocalcin (7.9 vs 10 ng/mL) and serum prealbumin (23 vs 27 mg/dL). Both patients and controls who took vitamin supplements had higher serum levels of vitamins than those not taking supplements. Compared with controls, in controlled analyses, CP patients had significantly lower levels of vitamins A, D, and E (both α-tocopherol and γ-tocopherol). CP patients also had significantly lower levels of osteocalcin, serum prealbumin, and retinol binding protein, and higher CRP.

CONCLUSIONS

CP patients demonstrated lower levels of selected nutrition and bone metabolism biomarkers than controls. Diabetes and alcohol did not impact biomarkers. Vitamin supplements and pancreatic enzyme replacement therapy improved nutrition biomarkers in CP patients.

Shwachman-Diamond syndrome: Nationwide survey and systematic review in Japan

BACKGROUND

Shwachman-Diamond syndrome (SDS) is a rare multisystem disorder associated with exocrine pancreatic insufficiency. The present study reports the results of a nationwide survey and a systematic review on SDS to develop consensus guidelines for intractable diarrhea including SDS.

METHODS

Questionnaires were sent to 616 departments of pediatrics or of pediatric surgery in Japan in a nationwide survey. A second questionnaire was sent to doctors who had treated SDS patients and included questions on clinical information. Additionally, a systematic review was performed using digital literature databases to assess the influence of medical (i.e. non-surgical) treatment on SDS prognosis.

RESULTS

Answers were received from 529 institutions (85.9%), which included information on 24 patients with SDS (median age, 10.4 years; male, n = 15) treated from January 2005 to December 2014. Although 75% of patients received pancreatic enzyme replacement therapy, there was no significant association between treatment and prognosis. Systematic review identified one clinical practice guideline, two case series, eight case reports and 26 reviews. Patient information from those studies was insufficient for meta-analysis.

CONCLUSIONS

The rarity of SDS makes it difficult to establish evidence-based treatment for SDS. According to the limited information from patients and published reports, medical treatment for malabsorption due to SDS should be performed to improve fat absorption and stool condition, but it is not clear whether this treatment improves the prognosis of malabsorption.

Diagnosis and management of pancreatic exocrine insufficiency (PEI) in primary care: consensus guidance of a Canadian expert panel

BACKGROUND

Pancreatic exocrine insufficiency (PEI) results in maldigestion due to inadequate activity of pancreatic enzymes in the small bowel. PEI can arise from a variety of medical conditions that reduce enzyme synthesis within the pancreatic parenchyma or from secondary factors that may occur despite optimal parenchymal function, such as pancreatic duct obstruction or impaired or poorly synchronized enzyme release.

PURPOSE

To provide practical guidance for primary care physicians managing patients who are at risk of PEI or who present with symptoms of PEI.

METHODS

For each of six key clinical questions identified by the authors, PubMed searches were conducted to identify key English-language papers up to April 2017. Forward and backward searches on key articles were conducted using Web of Science. Clinical recommendations proposed by the co-chairs (P.D. and C.T.) were vetted and approved based on the authors?

FINDINGS

The most characteristic symptom of PEI is steatorrhea ? voluminous, lipid-rich stools; other common signs and symptoms include unexplained weight loss and deficiencies of fat-soluble vitamins and other micronutrients. Pancreatic enzyme replacement therapy (PERT) can relieve symptoms and long-term sequelae of PEI. Diagnosis of PEI and initiation of PERT are usually the responsibility of gastroenterology specialists. However, primary care physicians (PCPs) are well positioned to identify potential cases of PEI and to participate in the collaborative, long-term management of patients already seen by a specialist.

CONCLUSIONS

In this document, a panel of Canadian gastroenterologists has conducted a critical review of the literature on PEI and PERT and has developed practical diagnostic and treatment recommendations for PCPs. These recommendations provide guidance on identifying patients at risk of PEI, the triggers for PEI testing and referral, and best practices for co-managing patients with confirmed PEI.

A primer on exocrine pancreatic insufficiency, fat malabsorption, and fatty acid abnormalities

Exocrine pancreatic insufficiency (EPI) is characterized by a deficiency of exocrine pancreatic enzymes, resulting in deficits in digestion of all macronutrients, with deficiencies in digestion of fats being the most clinically relevant. The leading cause of EPI is chronic pancreatitis. However, many other causes and conditions may be implicated, including cystic fibrosis, pancreatic duct obstruction, gastric and pancreatic surgery, diabetes mellitus and other conditions. Physical and biochemical causes of EPI include decreased production and secretion of lipase, increased lipase destruction, pancreatic duct obstruction, decreased lipase stimulation and degradation, as well as gastrointestinal motility disorders. EPI is largely diagnosed clinically, and is often identified by symptoms such as steatorrhea, weight loss, abdominal discomfort, and abdominal bloating. Lifestyle modifications (eg, smoking cessation, limiting or avoiding alcoholic drinks, and reducing dietary fat intake) and exogenous pancreatic enzyme supplements are commonly used to help restore normal digestion and absorption of dietary nutrients in patients with EPI.

Enteric hyperoxaluria in chronic pancreatitis

Chronic pancreatitis may lead to steatorrhea, enteric hyperoxaluria, and kidney damage. However, the prevalence and determinants of hyperoxaluria in chronic pancreatitis patients as well as its association with renal function decline have not been investigated.We performed an observational study. Urine oxalate to creatinine ratio was assessed on 2 independent random urine samples in consecutive adult patients with chronic pancreatitis followed at the outpatient clinic from March 1 to October 31, 2012. Baseline characteristics and annual estimated glomerular filtration rate (eGFR) change during follow-up were compared between patients with hyper- and normo-oxaluria.A total of 48 patients with chronic pancreatitis were included. The etiology of the disease was toxic (52%), idiopathic (27%), obstructive (11%), autoimmune (6%), or genetic (4%). Hyperoxaluria (defined as urine oxalate to creatinine ratio >32 mg/g) was found in 23% of patients. Multivariate regression analysis identified clinical steatorrhea, high fecal acid steatocrit, and pancreatic atrophy as independent predictors of hyperoxaluria. Taken together, a combination of clinical steatorrhea, steatocrit level >31%, and pancreatic atrophy was associated with a positive predictive value of 100% for hyperoxaluria. On the contrary, none of the patients with a fecal elastase-1 level >100 μg/g had hyperoxaluria. Longitudinal evolution of eGFR was available in 71% of the patients, with a mean follow-up of 904 days. After adjustment for established determinants of renal function decline (gender, diabetes, bicarbonate level, baseline eGFR, and proteinuria), a urine oxalate to creatinine ratio >32 mg/g was associated with a higher risk of eGFR decline.Hyperoxaluria is highly prevalent in patients with chronic pancreatitis and associated with faster decline in renal function. A high urine oxalate to creatinine ratio in patients with chronic pancreatitis is best predicted by clinical steatorrhea, a high acid steatocrit, and pancreatic atrophy. Further studies will need to investigate the mechanisms of renal damage in chronic pancreatitis and the potential benefits of therapies reducing oxaluria.

Pancreatic lipomatosis in cystic fibrosis: Rare manifestation of an uncommon disease

Cystic fibrosis is deemed to be uncommon in India. The presentation is usually in the childhood although more cases are now being recognized in adolescence and adulthood. We report a case of an adolescent male who had been treated for recurrent pulmonary infections and received anti-tubercular therapy for a possible diagnosis of sputum negative pulmonary tuberculosis and was evaluated for steatorrhea. The presence of pancreatic exocrine insufficiency along with pancreatic lipomatosis suggested the diagnosis of cystic fibrosis.

A case report on total pancreatic lipomatosis: An unusual entity

Total pancreatic lipomatosis (PL) is an unusual entity of pathologic significance and speculative origin. It refers to complete replacement of pancreatic parenchyma by fat cells. Fat replacement may vary from mild fatty infiltration to massive replacement of the pancreas by adipose tissue, resulting in malabsorption syndrome due to pancreatic insufficiency. We present a case of a 60-year-old elderly woman with atypical abdominal complaints, diabetes mellitus, weight loss, and steatorrhea. Abdominal computed tomograms were diagnostic of PL. Magnetic resonance imaging verified this impression. The patient improved clinically after the 8-week trial of high-dose oral pancreatic enzyme replacement therapy. There is a marked reduction of steatorrhea and weight gain. This case report focuses on pathophysiology, diagnosis, and treatment guidelines of PL.

Simple and noninvasive method for assessment of digestive efficiency: Validation of fecal steatocrit in greenfinch coccidiosis model

Animals’ capability to absorb energy and nutrients from food poses a major internal constraint that affects the amount of resources available for allocation to maintenance, growth, signaling, and reproduction. Intestinal surface is the largest area of contact between immune system and microbial antigens; gut thus appears the main arena where trade‐offs between immune function and other components of fitness arise. Assessment of the integrity of digestive machinery should therefore be of high priority in ecophysiological research. Traditional methods of digestive physiology, however, appear unsuitable for most ecological applications due to lethality or complexity of the procedure.

Here, we test the reliability of a simple, cheap, and noninvasive procedure, an acid steatocrit that assesses fat content in feces. It is based on centrifugation of a fecal sample, diluted in acid medium, in hematocrit capillary tube and quantifying the percentage of fat in fecal matter. The method has been previously validated in humans and mice; here, we apply it for the first time in birds.

When applied to captive wild‐caught greenfinches, the method showed reasonable internal consistency (r_s = 0.71 for steatocrit values, sampled from the same fecal aliquot in duplicate but processed separately). Individual steatocrit values were significantly repeatable in time in different intervals from eight to at least 20 days (r_s = 0.32–0.49). The relationship between intestinal health and steatocrit values was tested by experimental manipulations. Medication against coccidiosis (a naturally pervasive intestinal infection) reduced, and experimental infection with heterologous coccidian strains increased steatocrit. Individual changes in steatocrit correlated negatively with changes of two markers of nutritional state—plasma triglyceride levels and body mass.

Findings of this study suggest that steatocrit has a wide application potential as a marker of intestinal health in ecophysiological research. In particular, we see the perspective of this method for increasingly popular immunoecological research, conservation medicine, and studies of animal coloration.

Dietary thylakoids reduce visceral fat mass and increase expression of genes involved in intestinal fatty acid oxidation in high-fat fed rats

Thylakoids reduce body weight gain and body fat accumulation in rodents. This study investigated whether an enhanced oxidation of dietary fat-derived fatty acids in the intestine contributes to the thylakoid effects. Male Sprague-Dawley rats were fed a high-fat diet with (n = 8) or without thylakoids (n = 8) for 2 wk. Body weight, food intake, and body fat were measured, and intestinal mucosa was collected and analyzed. Quantitative real-time PCR was used to measure gene expression levels of key enzymes involved in fatty acid transport, fatty acid oxidation, and ketogenesis. Another set of thylakoid-treated (n = 10) and control rats (n = 10) went through indirect calorimetry. In the first experiment, thylakoid-treated rats (n = 8) accumulated 25% less visceral fat than controls. Furthermore, fatty acid translocase (Fat/Cd36), carnitine palmitoyltransferase 1a (Cpt1a), and mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase 2 (Hmgcs2) genes were upregulated in the jejunum of the thylakoid-treated group. In the second experiment, thylakoid-treated rats (n = 10) gained 17.5% less weight compared with controls and their respiratory quotient was lower, 0.86 compared with 0.91. Thylakoid-intake resulted in decreased food intake and did not cause steatorrhea. These results suggest that thylakoids stimulated intestinal fatty acid oxidation and ketogenesis, resulting in an increased ability of the intestine to handle dietary fat. The increased fatty acid oxidation and the resulting reduction in food intake may contribute to the reduced fat accumulation in thylakoid-treated animals.

Steatorrhea and hyperoxaluria occur after gastric bypass surgery in obese rats regardless of dietary fat or oxalate

PURPOSE

We determined the effect of dietary fat and oxalate on fecal fat excretion and urine parameters in a rat model of Roux-en-Y gastric bypass surgery.

MATERIALS AND METHODS

Diet induced obese Sprague-Dawley® rats underwent sham surgery as controls (16), or Roux-en-Y gastric bypass surgery (19). After recovery, rats had free access to a normal calcium, high fat (40%) diet with or without 1.5% potassium oxalate for 5 weeks and then a normal (10%) fat diet for 2 weeks. Stool and urine were collected after each period. Fecal fat was determined by gas chromatography and urine metabolites were evaluated by assay spectrophotometry.

RESULTS

Daily fecal fat excretion remained low in controls on either diet. However, Roux-en-Y gastric bypass rats ingested a food quantity similar to that of controls but had eightfold higher fecal fat excretion (p <0.001) and heavier stools (p = 0.02). Compared to controls, gastric bypass rats on the high fat diet with potassium oxalate had a fivefold increase in urine oxalate excretion (p <0.001), while gastric bypass rats without potassium oxalate had a twofold increase in urine calcium (p <0.01). Lowering dietary fat in gastric bypass rats with potassium oxalate led to a 50% decrease in oxalate excretion (p <0.01), a 30% decrease in urine calcium and a 0.3 U increase in urine pH (p <0.001).

CONCLUSIONS

In this Roux-en-Y gastric bypass model high fat feeding resulted in steatorrhea, hyperoxaluria and low urine pH, which were partially reversible by lowering the dietary fat and oxalate content. Roux-en-Y gastric bypass rats on normal fat and no oxalate diets excreted twice as much oxalate as age matched, sham operated controls. Although Roux-en-Y gastric bypass hyperoxaluria appears primarily mediated by gut and diet, secondary causes of oxalogenesis from liver or other mechanisms deserve further exploration.

Pancrelipase: an evidence-based review of its use for treating pancreatic exocrine insufficiency

Pancreatic exocrine insufficiency (PEI) is often observed in patients with pancreatic diseases, including chronic pancreatitis, cystic fibrosis, and tumors, or after surgical resection. PEI often results in malnutrition, weight loss and steatorrhea, which together increase the risk of morbidity and mortality. Therefore, nutritional interventions, such as low-fat diets and pancreatic enzyme replacement therapy (PERT), are needed to improve the clinical symptoms, and to address the pathophysiology of pancreatic exocrine insufficiency. PERT with delayed-release pancrelipase is now becoming a standard therapy for pancreatic exocrine insufficiency because it significantly improves the coefficients of fat and nitrogen absorption as well as clinical symptoms, without serious treatment-emergent adverse events. The major adverse events were tolerable gastrointestinal tract symptoms, such as stomach pain, nausea, and bloating. Fibrosing colonopathy, a serious complication, is associated with high doses of enzymes. Several pancrelipase products have been approved by the US Food and Drug Administration in recent years. Although many double-blind, placebo-controlled trials of pancrelipase products have been conducted in recent years, these studies have enrolled relatively few patients and have often been less than a few weeks in duration. Moreover, few studies have addressed the issue of pancreatic diabetes, a type of diabetes that is characterized by frequent hypoglycemia, which is difficult to manage. In addition, it is unclear whether PERT improves morbidity and mortality in such settings. Therefore, large, long-term prospective studies are needed to identify the optimal treatment for pancreatic exocrine insufficiency. The studies should also examine the extent to which PERT using pancrelipase improves mortality and morbidity. The etiology and severity of pancreatic exocrine insufficiency often differ among patients with gastrointestinal diseases or diabetes (type 1 and type 2), and among elderly subjects. Finally, although there is currently limited clinical evidence, numerous extrapancreatic diseases and conditions that are highly prevalent in the general population may also be considered potential targets for PERT and related treatments.

In Vitro Comparison of Physical Parameters, Enzyme Activity, Acid Resistance, and pH Dissolution Characteristics of Enteric-Coated Pancreatic Enzyme Preparations: Implications for Clinical Variability and Pharmacy Substitution

OBJECTIVE Pancreatic enzyme products were available before the 1938 passage of the Federal Food, Drug, and Cosmetic Act and have to date been marketed without required safety and efficacy testing. Despite a lack of demonstrated bioequivalence, they are often substituted for each other without physician or patient consent or monitoring. We investigated the in vitro variability of key performance parameters among a representative group of currently available pancreatic enzyme formulations.MATERIALS AND METHODS Three "branded" preparations (Creon 20 Minimicrospheres, Pancrease MT 20, Ultrase MT 20) and 3 "generic" formulations (Pangestyme CN-20, Pancrelipase 20,000 URL, and Lipram CR 20) were evaluated in vitro for physical parameters of the capsules, actual vs. labeled enzyme activity, resistance of the enteric coating to simulated gastric acid, and kinetics of simulated duodenal lipase release. All products were labeled as providing 20,000 units of lipase activity per capsule.RESULTS All products varied considerably in the percentage relationship between actual and labeled lipase activity. Actual lipase activity exceeded 165% of the label claim in 4 batches of the Pangestyme product and 1 batch of the Lipram product. All batches of the Creon, Lipram, Ultrase, and Pancrease products were found to have residual lipase activity above 80% of their baseline measurements after testing in simulated gastric acid; residual lipase activity varied significantly among batches of the Pangestyme product and was only 1% for the Pancrelipase product. The Creon and Lipram products demonstrated effective protection by the enteric coating at pH <6.0 and rapid release of enzymatic activity at pH ≥6.0. The Pangestyme and Pancrelipase products showed substantial activity of released enzymes already at pH 5.0. Release kinetics were inconsistent between batches for the Ultrase and Pancrease products.CONCLUSION This study confirms the existence of "branded"-to-"generic," product-to-product, and batch-to-batch variability among representative pancreatic enzyme formulations with pharmaceutically equivalent labels. The results confirm current cautions regarding pharmacy substitution of pancreatic enzyme products and support the announcement by the US Food and Drug Administration, made subsequent to this study, that as of April 2008 approved new drug applications will be required in order to ensure the quality, potency, and stability of these products.