Use of a standard fatty meal as a test for fat absorption

A quantitative assessment of serum chylomicron by light scattering intensity: application to the intestinal fat absorption test

A novel fat absorption test to clarify the malabsorption syndrome was developed using a micronephelometric technique and compared with the classic conventional technique using 131I-triolein. An integrity of time-sequential light scattered from chylomicron-related turbidity in serum was determined between 0 and 300 min after butter fat load, being expressed in terms of the light scattering intensity (LSI). A good correlation was obtained between LSI and the serum level of chylomicron-triglyceride determined by an ultracentrifugation technique (r = 0.819, P < 0.001). The maximal LSI was consistently observed at 180 min after administration of a test meal in the normal group (n = 39), whereas the malabsorption syndrome group (n = 35) was distinctly different and could be further classified according to four patterns of LSI changes. In addition, an inverse correlation was found between this fat absorption test and the 131I-triolein absorption test. It was concluded that the micronephelometric technique which does not use a radionuclide is advantageous in its simple and safe evaluation of fat malabsorption syndrome.

Digestive and nutritional consequences of pancreatic resections. The classical vs the pylorus-sparing procedure

Digestive and nutritional alterations are a common occurrence after pancreatic resections. The authors report the results of a multiparametric evaluation performed in a group of 26 patients submitted to total or cephalic pancreatectomy. Patients were divided into two groups according to the surgical procedure; group A (n = 13) included gastroresected patients and group B (n = 13) included those submitted to pylorus-sparing pancreatic resection. Subclinical digestive and absorptive impairment has been found in 61.5% of group A patients; the nutritional status was clinically poor in four cases from the same group. Digestive alterations have also been found in 69.2% of group B cases, but nutritional status was always satisfactory in the whole group. The more positive results obtained with the pylorus-sparing technique encourage wider adoption of this procedure.

Monitoring steatorrhoea in cystic fibrosis

The aim of the study was the evaluation of the relationship between chemical fat analysis and some more rapid tests proposed to estimate steatorrhoea. Stool collections (72 h) were obtained on 32 occasions in 22 patients with cystic fibrosis and in seven healthy children. A very close relationship was found between faecal fat, as measured by standard chemical methods, and faecal energy (r = 0.95, P < 0.001). We conclude that the determination of faecal energy, easier to measure than faecal fat, can provide reliable information about the extent of steatorrhoea in cystic fibrosis.

A new oral margarine loading test in children

Margarine (2g/kg) was orally administered to 39 children with normal fat digestion and absorption (control group) and 17 children with abnormal fat digestion and absorption (malabsorbed group). The serum triglyceride (TG) level was serially determined by capillary blood sampling. In the control group, the TG level was significantly elevated after 2, 3 and 4 h as compared with the level before margarine ingestion (basal TG). The maximum TG elevation rate [MTER = (maximum TG-basal TG)/basal TG x 100] was > 50% in all but three children. In contrast, a significant increase in TG was not observed in the malabsorbed group after margarine ingestion, and the MTER was < 50% in all but two children. The MTER was significantly lower in children with a high microscopic score of fecal fat than that in children with a low score. This oral margarine loading test is a simple and semi-quantitative evaluation of fat digestion and absorption, and is considered to be useful for the assessment of the presence or severity of fat maldigestion and malabsorption in children.

Butterfat absorption--a valuable screening test in malabsorption

The diagnosis of intestinal malabsorption is difficult to make without the use of specific tests such as endoscopic retrograde cholangiopancreatography (ERCP) or duodenal biopsy which are invasive and potentially hazardous. Faecal fat estimation or C14 Triolein breath tests have limitations as screening tools are time consuming and expensive. The butterfat absorption test (BFAT) is, in contrast, a simple, quick and cheap test for fat malabsorption. We have assessed the performance of this test in a blinded retrospective study of all such procedures performed in a teaching hospital over an 8 year period. One hundred and fourteen cases of suspected malabsorption had one or more butterfat tests. These were divided into absorbers and malabsorbers without knowledge of the butterfat test results. We found the butterfat test to have a sensitivity of 88% and a specificity of 94% using a cut-off of 20 light-scattering intensity units to discriminate normal from abnormal tests. At this level, predictive values are 91% for a positive result and 92% for a negative. These results are similar to those reported with the C14 Triolein breath test and adjusted faecal fats. We conclude that the butterfat test is a simple, cheap and effective screening test in the diagnosis of malabsorption.

Non-invasive assessment of intraluminal lipolysis using a 13CO2 breath test

Techniques available for the study of lipase activity in the gut are unsatisfactory. Breath tests measuring labelled carbon dioxide (13CO2) may provide a useful means for this assessment. Six subjects with cystic fibrosis and pancreatic insufficiency and 10 controls received a test meal containing [13C] trioctanoin, and breath 13CO2 was measured using a dual inlet, dual detector isotope ratio mass spectrometer. Comparison of postprandial breath 13CO2 enrichment allowed complete separation between children with pancreatic insufficiency and controls. Administration of one capsule of pancreatic enzyme with the test meal resulted in an increase in 13CO2 production in all six patients, and four capsules produced a further increase in five of the six. Serial fat balance studies on four of the patients while receiving comparable doses of oral enzyme failed to demonstrate a progressive improvement in fat absorption. The [13C]trioctanoin breath test may prove a safe, non-invasive technique not only for the detection of pancreatic insufficiency, but also for the quantitative study of intraluminal lipolysis.

Clinical monitoring of steatorrhoea in cystic fibrosis

In 100 patients with cystic fibrosis the severity of steatorrhoea was assessed by three separate methods. Using chemical faecal fat assay as the gold standard, two other rapid and inexpensive methods were compared with it. The steatocrit method proved unreliable in our hands and gave little indication of the presence or severity of steatorrhoea. The more simple microscopy method was highly sensitive (97%) and only three of 80 patients with steatorrhoea were missed. All patients with severe steatorrhoea (greater than 60 mmol fat/day) were clearly demonstrated. The method is applicable to spot faecal samples and can readily be carried out on an outpatient basis. In centres where faecal fat assays are not available, the simple and cheap microscopic examination will give some indication of the response to enzyme treatment and may also help to identify non-compliant individuals.

The fat meal test of malabsorption: some further experience

A fat meal test was evaluated in 21 healthy controls, 14 pathological controls and 11 malabsorption patients. The amount of fat used was 1 g per kg body wt, and the time for the post-cibal blood sampling was 2 h after the start of the meal. Combining serum triglyceride determination and serum turbidity measurement, the malabsorption group was fully discriminated from the control groups.

Assessment of fat malabsorption

For the assessment of fat malabsorption, the standard method of measuring faecal fat excretion using a 5 day stool collection has been compared with the alternative methods: stool microscopy, a lipid tolerance test and a continuous marker technique for the estimation of fat content on a single stool sample. The lipid test, using an emulsion of arachis oil (Prosparol), was less reliable than had been expected with a sensitivity of 33% and a specificity of 45.4%. Stool microscopy using Oil Red O to stain fat globules had a sensitivity of 72.2% and a specificity of 95.4%. Fat estimation of a single stool sample using copper (1) thiocyanate showed a high correlation with that determined on a 5 day stool collection (p less than 0.001). It is concluded that lipid tolerance tests have little place in the estimation of fat absorption. In laboratories where faecal fats are not measured, microscopic examination of stool for fat globules provides a specific and relatively sensitive method for detecting steatorrhoea. The use of a continuous marker provides a method for assessing the degree of steatorrhoea on a single stool sample without the disadvantages of the conventional method of faecal fat analysis.

A study of fat absorption in cystic fibrosis patients and controls by a rapid micro procedure: a comparison with fecal fat excretion method

Fat absorption was studied in 11 Cystic Fibrosis patients and 6 controls by measuring a) fecal fat excretion and b) serum turbidity using a nephelometer between 0 and 2 hours after a butter-fat load. Cystic Fibrosis patients showed a mean +/- SEM fecal fat excretion of 21.6 +/- 5.5%, and controls a mean of 2.7 +/- 0.45%, of the dietary fat. The turbidity change expressed as delta turbidity showed a mean value of 1.37 +/- 0.57 in Cystic Fibrosis patients and 31.8 +/- 5.7 in controls. Fecal fat excretion method showed a good negative correlation with the butter fat method. The butter fat absorption method was also compared with fecal fat excretion in rats with induced malabsorption and control rats. The results obtained were comparable to those in the patients. The method described here is rapid and can be performed with small blood volumes and therefore may be suitable to study fat malabsorption in pediatric patients.

Failure to heal D-deficiency rickets and suppress secondary hyperparathyroidism with conventional doses of 1,25-dihydroxy vitamin D3

Images

Comparison of simple screening tests for fat malabsorption

Three tests were evaluated as screening procedures for fat malabsorption--namely, measurement of serum optical density, serum triglyceride concentration, and 14CO2 breath excretion after the administration of a 60 g fat meal containing 10 muCi glycerol tri[1-14C]oleate. The results of these tests were compared with fat excreted in a three-day faecal collection after adjustment for completeness of collection as assessed by using non-absorbable radio-opaque markers. Fifty-two patients with various symptoms and eight normal subjects were studied. The maximum increase in serum optical density or triglyceride concentration above the fasting value discriminated poorly between subjects with normal and increased adjusted faecal fat excretion. In contrast, seven- or eight-hour cumulative 14CO2 breath excretion provided good discrimination with only four (7%) false-positive and no false-negative results. The simplicity and convenience of breath analysis make it an attractive alternative to analysis of faecal fat excretion in screening for fat malabsorption.

Clinical value of 14C-phenylacetic oil as a fat absorption test

The value of [1-14C] phenylacetic oil as a clinical test for malassimilation was evaluated in 20 normal volunteers, 20 patients with various non-gastrointestinal illnesses, 10 patients with malabsorption, and 7 patients with maldigestion. All subjects were given a test meal composed of 0.5 ml of 14C-phenylacetic oil (0.5 muCi) in 30 g of cheese and 40 g of bread. The test was simultaneously run with D-xylose. Urine was collected over a 5 h period and assayed for 14C and D-xylose. Mean urinary recovery of 14C label in volunteers was 65 +/- 15% of th: administered dose. All 10 patients with malabsorption had abnormal D-xylose excretion and excreted less than 35% of the 14C-phenylacetate. 6 of 7 patients with maldigestion excreted less than 15%, while in the 7th patient excretion of 14C label was borderline (35%). 4 of the 7 patients with maldigestion had abnormal D-xylose excretion, probably as a result of bacterial overgrowth. The procedure described is a cost-effective, simple, rapid, and safe test for fat absorption which may be conveniently run with a D-xylose excretion test.

Plasma triglyceride increase after oral fat load in malabsorption during early childhood

Plasma triglyceride (TG) levels were determined before and after a test meal of 2 g neutral fat per kg b.w. in 32 children with different malabsorption syndromes, 8 children with transient growth retardation without demonstrable disease and in 29 controls. The increase of plasma TG 120 min after the test meal was found to discriminate between children with malabsorption syndromes and controls during the studied age period, 1 month-3 years. In this respect it was superior to faecal fat determination. Children with transient growth retardation who later spontaneously regained satisfactory growth, although along a lower SD score than the initial one, showed a TG increase after the test meal comparable to that of the controls.

Phenylacetic oil: a possible simple test for fat absorption

The preparation of a phenyl[1-14C]acetic acid oil is described. The absorption pattern of the phenylacetate in this oil is similar to that of oleic acid in triolein when examined in rats under conditions that may interfere with digestion and/or absorption. The safety of this compound, which is a normal metabolite, was established by the absence of the 14C label in various tissues five days after its administration to rats. When tested in 18 normal human volunteers 66.6 +/- 16.0 (S.D.) percent of the phenylacetate was recovered in a five hour urine collection. In two patients with malabsorption, less than 30% of the label was recovered in the urine over the same period. The half-life of the phenylacetate was determined to be 1-1.5 h. Our preliminary results indicate that phenylacetic oil may serve as a useful simple clinical test for fat absorption.

Changes in plasma nephelometry after oral fat loading in children with normal and abnormal small intestinal morphology

A standardized oral fat load has been given to 66 children having duodenal or jejunal biopsy, and to 10 children presumed normal. The rise in plasma light scattering intensity (LSI) measured by nephelometry between the fasting and 2-hour postload level (0-2 hour) showed good correlation with the small intestinal morphology in patients suspected of having coeliac disease. In those who had had recurrent diarrhoea and gastroenteritis, the fat load test did not predict small intestinal morphology. Serial studies in 5 treated patients with malabsorption showed increase in the 0-to 2-hour LSI, with corresponding improvement of small intestinal morphology and clinical state.

The short-term response to a drink of milk, lactose or casein in children with apparently normal gastrointestinal tracts

1. Drinks of milk, lactose and casein were given to children who, though suspected of having malabsorption, were subsequently found to have normal gastrointestinal tracts. The plasma concentrations of glucose, amino acids, urea and insulin following these drinks were measured. The results can probably be taken to represent control values when investigating children with gastrointestinal or metabolic disorders.

2. The rise in plasma amino acids after giving casein and the rise in plasma glucose after giving lactose were greater than those after giving equivalent amounts of milk.

3. The absorption of an individual food constituent and its uptake by the tissues are influenced by the presence of other food constituents so that ‘tolerance tests’ with individual nutrients may not be truly physiological.