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The intestinal permeation and 6-hour urinary recovery of small, multisized tracers, polyethyleneglycol 400 (PEG 400), was used to characterize gut permeability in nine patients after bypass surgery for morbid obesity and in ten healthy volunteers. In the patients, who also had hyperoxaluria, the urinary recovery of ingested PEG 400 was lower than in the healthy persons (10.9 and 24.7%). The patients also showed stronger intestinal exclusion of the larger polymers within the PEG 400.

Jejuno-ileal bypass operations have been used for more than 20 years for the treatment of massive obesity. This treatment results in malabsorption with diarrhoea, especially during the first year after operation. A high incidence of urinary tract calculi was found in these patients (Backman & Hallberg, 1972; Dickstein & Frame, 1973; O'Leary, Thomas & Woodward, 1974; Backman et al., 1975; Gregory et al., 1975). Other known late complications are transient disturbances in liver function and electrolyte balance (Backman et al., 1975). Different types of operations result in different frequencies of kidney stones.

Jejunoileal bypass operations have been used for more than 20 years for the treatment of massive obesity. This treatment results in malabsorption with diarrhoea, especially during the first year after the operation. A high incidence of urinary tract calculi have been found in these patients (4, 5, 15, 19, 24). Other known late complications are transient disturbances in liver function and electrolyte balance (5).

The urinary excretion of oxalate, calcium, magnesium and citrate as well as the inhibition of calcium oxalate crystal growth in diluted urine was studied in seven patients with hyperoxaluria following jejunoileal bypass. The study was performed on an outpatient basis before and during daily administration of 38 or 113 mmol calcium, 28 mmol of aluminum, 20 mmol of magnesium or 16 g of cholestyramine. Each substance was administered for seven days with a free interval of at least seven days. The mean urinary oxalate excretion was not reduced with any of these regimens. Administration of 38 mmol of calcium per day resulted in increased oxalate and magnesium excretion. Increased excretion of both calcium and citrate was observed during administration of 113 mmol of calcium per day. Calcium and magnesium excretion was increased with aluminium. An increased magnesium excretion was also observed during administration of magnesium, resulting in a decreased calcium/ magnesium ratio. Cholestyramine resulted in increased oxalate and decreased citrate excretion.

The postoperative period after small intestine bypass operations could be subdivided into five. Analysis of the rate of weight loss during the period of constant weight loss (period II) in 80 subjects gave a mean rate of 0.011 weight-index units (Broca) per week (range 0.023-0.003) or 0.79 kg per week (range 1.81-0.22). After both end-to-end and end-to-side jejuno-ileostomy the rate of weight loss during period II was correlated to initial body weight. After end-to-end jejuno-ileostomy the rate of weight loss was also correlated to the length of the distal eleum in function, either as absolute value or as a fraction of the total small intestinal length. The absence of these correlations after end-to-side jejuno-ileostomy might be due to a more variable reflux in to the bline loop after this operation. It is suggested that a small intestinal bypass operation should not be performed as a standardized procedure with predetermined segments of the small intestine in function, but rather as an operation designed for each patient.

Previous studies have shown that the severity of enteric hyperoxaluria can be reduced in hospitalized patients who receive a diet low in oxalate and fat. Little is known of the value of such a diet in the patients' home conditions. Ten patients with hyperoxaluria (greater than 0.45 mmol/24 h) following jejuno-ileal bypass were therefore studied while on their ordinary diet and also on a diet with low-oxalate, low-fat content. The mean urinary excretion of oxalate decreased during the dietary treatment from 1.1 to 0.7 mmol/24 h. The diet was demanding, though not unfeasible for the patients. Careful and regular dietary information, preferably by a dietitian, is recommended in such cases.

The urinary excretion of oxalate, calcium, citrate, magnesium, urate and creatinine and the inhibition of calcium oxalate crystal growth were determined in 30 patients operated with three different types of jejunoileal bypass. In addition the ion-activity products of calcium oxalate and calcium oxalate saturation were calculated. 15 of the patients had formed urolithiasis postoperatively. The patients were investigated on an out-patient basis with their ordinary diet. All patients had hyperoxaluria. The oxalate excretion did not seem to decrease with time after operation. The patients operated with a biliointestinal shunt had a significantly higher excretion of oxalate than those with the other two types of operation, indicating that variations in the anatomy of the small intestine after jejunoileal bypass might result in different absorption of oxalate or oxalate precursors. Urinary oxalate, calcium oxalate saturation and ion-activity products were higher whereas the excretion of calcium, magnesium and citrate was lower in patients than in controls. The urine volumes, excretion of creatinine and urate and inhibition of calcium oxalate crystal growth were equal in patients and controls. Analogous urine composition was found in patients both with and without urolithiasis with the exception of a higher magnesium excretion observed in stone formers.

The forty-seven patients in this study suffered of massive obesity and underwent jejuno-ileal shunt operations. Seventeen of them had a second laparotomy for various reasons. At both operations, a number of measurements were made; the length of the functioning jejunal and ileal segments and, in biopsies, the intestinal villus height were determined. The second laparotomies were not performed until at least 6 months after establishment of jejuno-ileal bypass. The mean length of functioning jejunum was increased by 33% (p less than 0.05) and the mean elongation of functioning ileum by 73% (p less than 0.001). The mean villus height in functioning jejunum increased by 33% (p less than 0.001) and in functioning ileum by 70% (p less than 0.001). The mean villus height in the jejunal blind loop decreased by 30% (p less than 0.001). The demonstrated hypertrophic changes in the functioning part of the small intestine following jejuno-ileal bypass represent the morphological basis of functional intestinal adaptation. The effect of this adaptation is clearly shown in the characteristic weight diagram of an obese patient after bypass operation: the loss of weight cases, a period of stability ensues and then the patient begins to regain weight to some extent.

The amino acid pattern in plasma was studied in a reference group (n=26) and in three groups of massive obese subjects (n=9, 8, and 9 respectively) before and at intervals after jejuno-ileostomy. The obese subjects had preoperatively an amino acid pattern significantly different from that in the reference group. The concentrations of lysine, tyrosine, 1/2 cystine, and glutamic acids were higher, and aspargin, glutamine, serine, and glycine were lower than in the reference group. During the post-operative period the amino acid pattern changed significantly; thus serine, glycine, and taurine increased and valine, lysine, leucine, tryptophan, thyrosine, 1/2 cystine, and citrulline decreased. The amino acid pattern in the obese group with the longest post-operative observation time and a stable body weight differed significantly from that in the reference group only with regard to a low valine concentration and high concentration of taurine and glutamatic acid.

Twenty-nine patients who had undergone four different types of jejunoileal bypass for obesity were examined roentgenologically after ingestion of barium contrast. Functional intestinal length, blind loop reflux and speed of contrast through the small intestine were recorded. Weight loss was not correlated to any of the mentioned parameters or to operative method. Length of functioning intestine increased and speed of contrast decreased with time after surgery.