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Composition of feces in steatorrhea of different etiology: mutual relationship between the volume of feces, water, dry matter, nitrogen, and fat content
In the present investigation, suitability of nuclear magnetic resonance (NMR) spectrometry for total stool fat quantification in patients with normal or impaired exocrine pancreatic function (chronic pancreatitis) has been analyzed in comparison with a conventional chloroform-methanol extraction technique. Basic temperature-dependence studies of NMR spectrometry (90/180 radiofrequency pulse sequence) on 21 chloroform-methanol extracted pure total stool lipid standards (weight range: 0.05–1.6 g) revealed significantly (Pr=0.952/40 C,r=0.965/60 C,r=0.988/80 C), thus indicating 80 C as optimal temperature for NMR spectrometric total stool fat quantification. In subsequent comparative measureemnts of lyophilized stool samples, NMR spectrometry (at 80 C) and conventional chloroform-methanol extraction provided significantly (Pr=0.983) or separately for patients with normal (N=45;r=0.867), moderately reduced (N=31;r=0.946), or highly reduced (N=17;r=0.992) exocrine pancreatic function and correspondingly increased total fecal fat excretions.
Diarrheal disorders are the result of excessive fluid and electrolyte loss through the gastrointestinal tract. Many different underlying mechanisms are known to cause diarrhea. Fordtran suggested that in secretory diarrhea the osmolality of stool water should be accounted for by its electrolyte contents. Therefore, the osmotic gap between the measured osmolality and that estimated from electrolyte contents should be small. In osmotic diarrhea, due to the presence of the osmotic agent, there should be a greater gap between the measured and the estimated osmolalities. Osmotic gaps varying from 100 to 40 mOsm have been used arbitrarily in literatures to define the underlying pathogenesis. Because of the uncertainty, the usefulness of these measurements remains in question. In this article, methods used to measure stool osmolality and electrolyte contents are reviewed. Limitations of these measurements are discussed. Measurements derived from various diarrheal disorders revealed that the basic concepts put forward by Fordtran are corrected. However, we found that the osmotic gaps (measured osmolality - 2 [Na + K] in secretory diarrheal disorders are frequently negative numbers. In osmotic diarrhea, the osmotic gap (greater than 160 mOsm) is substantially greater than the figures used in the literature. In many diarrheal disorders the osmotic gap falls between the two extremes and the pathogenesis is multifactorial in origin. Under these circumstances, stool osmolality and electrolyte measurements provide little insight into the underlying mechanism causing the diarrhea. Furthermore, stool contains many biologically active organisms which can alter the stool osmolality. Unless these effects are appreciated, an inaccurate interpretation of these measurements may result.
Factors influencing the density of stools from 33 healthy subjects (nine had floating and 24 sinking stools) and six patients with steatorrhea were investigated. All floating stools sank when their gas volume was compressed by positive pressure. Thus, to float, stools must contain gas. After degassing, previously floating and sinking stools had similar specific gravities, indicating that the floating or sinking propensity of such stools depends upon differences in gas rather than fat content. A high stool gas content (and hence a floating stool) in healthy subjects appeared related to colonic methane production. Steatorrheic stools had a relatively normal gas content. The density of their nongaseous fraction was less than normal, but resulted primarily from increased water rather than fat content. Thus, stools float because of an increased content of gas or water (or both); the floating stool should not be considered a sign of steatorrhea.
The role of decreased absorption of electrolytes and water by the jejunum in the pathogenesis of diarrhoea was examined in patients with intestinal scleroderma, ileocolitis, gastric hypersecretion, or extensive ileal resection. Absorption of electrolytes and water from a 20-cm segment of jejunum was compared in 10 patients and six healthy volunteers. Malabsorption of electrolytes and water by the jejunum may contribute to diarrhoea in scleroderma, regional enteritis, and gastric hypersecretion. After ileal resection, jejunal absorption was normal.
Loose stools are a common and troublesome feature in diarrhea. The purpose of this study was to investigate factors that determine different degrees of stool looseness in diarrhea.
Fecal consistency was measured visually. Stools were analyzed for content of water and solids. Water-holding capacity of insoluble solids was measured in vitro.
Formed stools from normal subjects had a near constant ratio of water to solids despite a sevenfold variation in daily stool weight. In diarrhea, loose consistency was correlated directly with percent fecal water. For any level of percent water, steatorrhea stools were looser than nonsteatorrhea stools. Ingestion of psyllium reduced stool looseness without changing the percent water. Both the effect of fat and psyllium could be explained by consideration of the ratio of fecal water to water-holding capacity of insoluble solids.
(1) The normal intestine delivers stools that differ widely in quantity but maintains percent fecal water within a narrow range. (2) Stool looseness in diarrhea is determined by the ratio of fecal water to water-holding capacity of insoluble solids. (3) In patients with diarrhea with normal stool weight, loose stools are due to low output of insoluble solids without the concomitant reduction in water output that occurs in normal subjects when insoluble solids are low.