Fecal Fat Analyses in Chronic Pancreatitis Importance of Fat Ingestion before Stool Collection

Assessment of exocrine pancreatic function in children and adolescents with direct and indirect testing

The exocrine pancreas plays an important role in digestion. Understanding of the physiology and regulation of exocrine function provides insight into disease processes and basis of functional testing. Specifically, exocrine pancreatic insufficiency (EPI) can cause maldigestion and thus a proper assessment of exocrine pancreatic function is important. There are indirect and direct methods for evaluating pancreatic function. Indirect methods are varied and include stool, serum, urine, and breath tests. Fecal elastase is a commonly used indirect test today. Direct methods involve stimulated release of pancreatic fluid that is collected from the duodenum and analyzed for enzyme activity. The most used direct test today is the endoscopic pancreatic function test. Indirect pancreatic function testing is limited in identifying cases of mild to moderate EPI, and as such in these cases, direct testing has higher sensitivity and specificity in diagnosing EPI. This review provides a comprehensive guide to indirect and direct pancreatic function tests as well as an in-depth look at exocrine pancreatic function including anatomy, physiology, and regulatory mechanisms.

Neither low salivary amylase activity, cooling cooked white rice, nor single nucleotide polymorphisms in starch-digesting enzymes reduce glycemic index or starch digestibility: a randomized, crossover trial in healthy adults

BACKGROUND

It was suggested that low salivary-amylase activity (SAA) and cooling or stir-frying cooked starch decreases its digestibility and glycemic index.

OBJECTIVE

We determined the effects of SAA, cooling, and single-nucleotide polymorphisms (SNPs) in the salivary amylase (AMY1), pancreatic amylase (AMY2A, AMY2B), maltase-glucoamylase (MGAM), and sucrase-isomaltase (SI) genes on starch digestibility and glycemic index of cooked polished rice.

METHODS

Healthy subjects [pilot, n = 12; main, n = 20 with low-SAA (<50 U/mL), and n = 20 with high-SAA (>105 U/mL)] consumed test meals containing 25 g (pilot) or 50 g (main) available carbohydrate at a contract research organization using open-label (pilot) or assessor-blinded (main), randomized, crossover, Latin-square designs (trial registration: NCT03667963). Pilot-trial test meals were dextrose, freshly cooked polished rice, cooked rice cooled overnight, stir-fried hot rice, or stir-fried cold rice. Main-trial test meals were dextrose, dextrose plus 10 g lactulose, plain hot rice, or plain cold rice. In both trials, blood glucose was measured fasting and at intervals over 2 h. In the main trial, breath hydrogen was measured fasting and hourly for 6 h to estimate in vivo starch digestibility. Data were analyzed by repeated-measures ANOVA for the main effects of temperature and stir-frying (pilot trial) or the main effects of SAA and temperature (main trial) and their interactions. Effects of 24 single nucleotide polymorphisms (SNPs) were assessed separately. Means were considered to be equivalent if the 95% CI of the differences were within ±20% of the comparator mean for glucose response/glycemic index or ±7% for digestibility.

RESULTS

Pilot: neither temperature nor stir-frying significantly affected glucose incremental AUC (primary endpoint, n = 12). Main: mean ± SEM glycemic index (primary endpoint, n = 40) was equivalent for low-SAA compared with high-SAA (73 ± 3 vs. 75 ± 4) and cold rice compared with hot rice (75 ± 3 vs. 70 ± 3). Estimated starch digestibility (n = 39) was equivalent for low-SAA compared with high-SAA (95% ± 1% vs. 92% ± 1%) and hot rice compared with cold rice (94% ± 1% vs. 93% ± 1%). No meaningful associations were observed between genotypes and starch digestibility or glycemic index for any of the SNPs.

CONCLUSIONS

The results do not support the hypotheses that low-SAA, cooling, and common genetic variations in starch-digesting enzymes affect the glycemic index or in vivo carbohydrate digestibility of cooked polished rice. This trial was registered at clinicaltrials.gov as NCT03667963.

Diarrhea due to SARS-CoV-2-Related Exocrine Pancreatic Insufficiency

Gastrointestinal symptoms, especially diarrhea, are common with novel coronavirus SARS-CoV-2 infection. Angiotensin-converting enzyme-2 (ACE-2) receptors are heavily expressed in enterocytes and serve as entry receptors for SARS-CoV-2. ACE-2 receptors may also be responsible for pancreatic injury in patients infected with SARS-CoV-2. Diarrhea associated with SARS-CoV-2 is usually believed to be due to viral invasion of enterocytes. However, exocrine pancreatic insufficiency resulting from SARS-CoV-2 is another plausible mechanism leading to diarrhea in such patients. We present a case series of three SARS-CoV-2-infected patients with predominant respiratory symptoms at presentation who developed diarrhea, and further fecal analysis revealed exocrine pancreatic insufficiency as the underlying mechanism.

Pancreatic Function in Chronic Pancreatitis: A Cohort Study Comparing 3 Methods of Detecting Fat Malabsorption and the Impact of Short-term Pancreatic Enzyme Replacement Therapy

OBJECTIVES

Reliable pancreatic function tests in patients with chronic pancreatitis (CP) are needed. This cohort study identified malabsorption in people with CP compared with healthy people and then investigated short-term pancreatic enzyme replacement therapy (PERT) and fat malabsorption, nutritional status, and quality of life (QOL).

METHODS

Subjects with CP were evaluated before and after PERT and compared with the healthy cohort using coefficient of fat absorption (CFA), stool bomb calorimetry, and the malabsorption blood test (MBT). Anthropometrics, micronutrients, and QOL data were collected. Group means at baseline and after PERT were analyzed.

RESULTS

The 24 subjects with CP had greater stool energy loss (5668 cal/g [standard deviation {SD}, 753] vs 5152 cal/g [SD, 418], P < 0.01), reduced triglyceride absorption (MBT, 8.3 mg·h/dL [SD, 4.3] vs 17.7 mg·h/dL [SD, 10.3], P < 0.001), lower fat intake, and poorer QOL. Differences in CFA were not significant (90.9% [SD, 12.8] vs 95.4% [SD, 9.3]). After PERT, triglyceride absorption (Δ = 1.7 [SD, 3], P < 0.05) and QOL increased.

CONCLUSIONS

The MBT detected changes in triglyceride absorption in the absence of CFA changes. The MBT may be helpful in guiding PERT initiation in patients with CP before significant morbidity.

Challenges in the management of pancreatic exocrine insufficiency

Pancreatic exocrine insufficiency (PEI) occurs when the insufficient secretion or function of pancreatic enzymes leads to maldigestion, most commonly as a result of chronic pancreatitis and pancreatic cancer. The condition is associated with significant morbidity and reductions in quality of life, even in milder forms. The challenges in approaching this condition include the non-specific presentation of mild to moderate PEI, and the lack of a convenient, accurate diagnostic test in this cohort. Classical symptoms appear late in the disease, and the diagnosis should be considered before steatorrhoea develops. Direct pancreatic function tests are the reference standard for diagnosis, but are invasive and not widely available. The faecal elastase-1 (FE-1) stool test is widely available and has been shown to be as effective as the 13C-mixed triglyceride breath test in more advanced disease. We recommend a pragmatic diagnostic approach that combines clinical history, assessment of nutritional status and measurement of FE-1. The critical first step is to consider the diagnosis. Once the diagnosis is confirmed, pancreatic enzyme replacement therapy should be initiated. The variety of enzyme preparations and recommended dosing regimens can present a challenge when selecting an adequate initial dose. Non-response should be actively sought and addressed in a systematic manner. This article discusses these challenges, and presents a practical approach to the diagnosis and management of PEI.

Fecal fat and energy loss in pancreas exocrine insufficiency: the role of pancreas enzyme replacement therapy

BACKGROUND

Chronic pancreatitis (CP) can lead to severe pancreatic exocrine insufficiency (PEI). Pancreatic enzyme replacement therapy (PERT) is well established, but knowledge of the physiological response to increasing doses on fecal fat- and energy loss is scarce.

METHODS

We included 10 patients with CP and established PEI and 12 healthy controls for a prospective interventional study. Subjects received no PERT in the first week followed by four weeks PERT incrementally increasing doses every week. For each week, three-day stool collection followed three days registration of nutritional intake. We measured the fecal output of fat and energy by van de Kamer titration and decomposition vessel calorimetry, respectively. We calculated fecal fat- and energy loss per day, the coefficient of fat absorption (CFA) and coefficient of energy absorption (CEA).

RESULTS

Without PERT treatment, CP patients with PEI had significantly higher daily fecal fat and energy loss (p = .022; p = .035) compared to HC. In CP patients, there was a significant reduction of fecal fat and energy loss (p = .045; p = .037) when PERT doses reached maximum intake of 75,000 units per meal. In CP patients, there was a strong positive correlation between fecal loss of energy and fat (r = 0.99), and between fecal loss of energy and daily stool weight (r = 0.97). CFA and CEA correlated negatively with daily fecal fat loss (r = -0.72) and fecal energy loss (r = -0.65).

CONCLUSIONS

PERT reduces fecal energy and fat loss in patients with CP and PEI. Fecal energy loss in CP patients is strongly dependent on fecal fat loss, and on fecal weight.