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Post-op hypoglycaemia

Additional surgery for severe post-op hypoglycaemia

Reconstruction of gastrojejunal continuity might be the safest and most successful option

Reconstruction of gastrojejunal continuity may be the safest and most successful procedure for patients who present with post-operative hypoglycaemia following bariatric surgery and do not respond to pharmacological treatment, according to a study published in the journal Obesity Facts. According to the Swedish Nationwide cohort study, 0.2% of patients undergoing Roux-en-Y gastric bypass (RYGB) suffer from this complication.

The researchers from Spain note that although severe postprandial hypoglycaemia after bariatric surgery is rare, but that can be disabling for the patient. In their paper’ ‘Hyperinsulinemic Hypoglycemia after Bariatric Surgery: Diagnosis and Management Experience from a Spanish Multicenter Registry’, they describe the different tests performed for its diagnosis and their outcomes as well as the response to the prescribed pharmacological and surgical treatments.

The researchers retrospectively collected detailed clinical and biochemical data by reviewing medical charts of all patients who had previously undergone bariatric surgery (RYGB and malabsorptive procedures) during the period from January 2002 to December 2013 in the 12 tertiary reference public hospitals in Spain.

They identified 22 patients from 4,645 bariatric surgery interventions (0.47%). Nineteen patients (86.3%) had undergone a standard RYGB and three a malabsorptive procedure. Elapsed time since bariatric surgery was 31.8 ± 26 months (range 7-120 months). At the time of hypoglycaemic episodes, 77% of patients had regained weight (10.7 ± 16% from their minimal weight after surgery). The hypoglycaemic events were mainly postprandial, but 27% of patients presented with mixed episodes pre- and postprandially. The clinical characteristics of patients and laboratory values during episodes of postprandial hypoglycaemia are shown in Table 1.

Table 1: The clinical characteristics of patients and laboratory values during episodes of postprandial hypoglycaemia

Regarding the characteristics of patients, none suffered from hypoglycaemic episodes before surgery, and type 2 diabetes was present in 9% of them remitting after the procedure, without requiring any hypoglycaemic drugs.

Tests

Only 3 (13.6%) of patients had plasma insulin concentrations determined during a spontaneous episode of hypoglycaemia; in the remaining subjects, insulin and glucose levels were analysed along with venous glucose sampling during the provocative test. The laboratory findings confirmed hyperinsulinemia or an inappropriate normal insulinemia in all patients and a concomitant venous glucose level of less than 50mg/dl (mean 39.1 ± 9.3 mg/dl).

The test most used to provoke a hypoglycaemic episode was the oral glucose load, which was performed in 16 (72%) patients. In 11 (50%) patients, a mixed meal test was done as an exclusive test (n=3) and in addition to an oral glucose load (n=8). During the oral glucose load, 81% of patients experienced a hypoglycaemic event. In two patients, this test was not assessable because of vomiting. During the mixed meal test, 54% of patients had a hypoglycaemic event.

“Approximately 30% of these episodes will not respond to pharmacological treatment…In these cases radiological studies and a calcium stimulation test should be performed."

Comparing the eight patients evaluated both with an oral glucose load and with a liquid mixed meal test, a greater proportion showed a positive result (presence of hypoglycaemia) after the oral glucose load test (66% vs. 33%, p=0.049). The mixed meal was the best tolerated test, although the least standardized. Different times of sample collection and total duration (ranging from 120 to 240 min) were reported. Also, different liquid meals were used containing 33-50g of carbohydrates (mean 39.5±5.3g). A 72-hour fast was performed in ten (45%) patients, mainly in patients with mixed pre- and postprandial episodes, and in 70% of them hypoglycaemia was observed, but with low plasma insulin concentrations.

An exploratory glucose sensor was placed in only three patients, and hypoglycaemic events were detected in all of them during a 5-day period.

Pharmacological Treatment

The first step in the pharmacological treatment was the use of α-glucosidase inhibitors, only 4four patients (18%) showed a partial response. A reduction of 50% in the number of hypoglycaemic events and in their severity was considered a partial response. The second step was the use of a calcium channel blocker in ten (45.4%) patients (nifedipine and verapamil at doses of 20mg and 80mg, respectively), and of diazoxide (mean dose 168.7±94mg/day) in six (27.2%). The results obtained with both previous treatments were similar, achieving an initial reduction of symptoms in 50% of patients.

Octreotide was used as a second pharmacological treatment step after α-glucosidase inhibitors in two patients and as a third step in 11 patients (eight without response and three with partial response after calcium channel blockers/diazoxide). Among patients receiving octreotide, five (38.4%) showed a partial response and in three (23%) the hypoglycaemic episodes resolved.

In the follow-up, two patients with partial response under calcium channel blockers and diazoxide experienced a worsening of their symptoms. Therefore, with pharmacological treatment, three patients were symptom-free (with octreotide) and 12 experienced an attenuation of their hypoglycaemic episodes (with α-glucosidase inhibitors n=4, with calcium channel blockers n=3, with octreotide n=5). Seven patients with persistent severe hypoglycaemic episodes underwent further studies.

Radiological Studies

Abdominal CT and ecoendoscopy were performed in the former seven patients, and octreotide scintigraphy was performed in three patients, without pathological findings. Selective arterial calcium stimulation was undertaken, and it was positive in three patients.

Surgical Treatment

Partial pancreatectomy was performed in three patients with positive selective arterial calcium stimulation. In two of them, neosidioblastosis was confirmed. After the intervention they were symptom-free, one or two years after surgery. In one patient, no histologically abnormal findings were observed, and hypoglycaemic episodes persisted, requiring a reconversion of duodenal switch to original anatomy. However, two years later hypoglycaemic episodes recurred and were controlled with α-glucosidase inhibitors during the next three years. After this period of time, type 2 diabetes mellitus was diagnosed and required treatment with insulin and metformin.

Redo surgery (revisional or conversional surgery) was chosen as a first surgical therapeutic option in four patients with previous RYGB. One of them underwent a ‘kissing operation' with performance of an anastomosis between the alimentary limb and the antral remnant. However, two years later, because of recurrence, the alimentary limb was removed and the gastric pouch was anastomosed to the gastric remnant to restore the gastroduodenal tract continuity. The patient persisted with hypoglycaemic episodes that could be controlled with α-glucosidase inhibitors. Two other patients underwent a complete reversal of RYGB to normal anatomy. The procedure consisted in dismantling the previous gastrojejunostomy and jejunojejunostomy, re-anastomosing the gastric pouch to the gastric remnant and the proximal alimentary limb end to the distal biliary limb end. The two patients have been without evidence of hypoglycaemia for one year or for three months after the intervention.

The last patient with RYGB (patient number 4) showed recurrence of hypoglycaemic episodes after an initial resolution with octreotide. She underwent a gastric pouch restriction, reducing the anastomosis diameter and a resection of the non-functional Roux limb proximal to the jejunostomy in order to avoid the ‘candy cane' Roux syndrome associated with hypoglycaemia. The patient is symptom-free one year after the procedure.

“Postoperative hypoglycaemia is an uncommon, yet troublesome, side effect after RYGB. There is high heterogeneity in the initial evaluation and treatment options, and most authors follow their own experience as there is no established consensus,” they authors conclude. “Approximately 30% of these episodes will not respond to pharmacological treatment…In these cases radiological studies and a calcium stimulation test should be performed. Reconstruction of gastrojejunal continuity might be the safest and most successful option. Partial or subtotal pancreatic resection has high morbimortality, can lead to the onset of diabetes and should be applied only when a clear gradient is found in venous sampling.”

The article was edited from the original article, under the Creative Commons license. To access the article, please click here

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