Growth Hormone Favorably Affects Bone Turnover and Bone Mineral Density in Patients With Short Bowel Syndrome Undergoing Intestinal Rehabilitation

BACKGROUND

Patients with short bowel syndrome (SBS) have a high prevalence of metabolic bone disease due to nutrient malabsorption and potential effects of parenteral nutrition (PN). Human growth hormone (hGH) has been shown in some studies to have anabolic effects on bone, but hGH effects on bone in patients with SBS are unknown.

METHODS

Adults with PN-dependent SBS underwent a 7-day period of baseline studies while receiving usual oral diet and PN and then began receiving modified diets designed to improve nutrient absorption and daily oral calcium/vitamin D supplements (1500 mg elemental calcium and 600 IU vitamin D, respectively). Subjects were randomized to receive in a double-blind manner either subcutaneous (sc) saline placebo as the control or hGH (0.1 mg/kg/d for 3 weeks, then 0.1 mg/kg 3 days a week for 8 subsequent weeks). Open-label hGH was given from week 13 to week 24 in subjects who required PN after completion of the 12-week double-blind phase. Markers of bone turnover (serum osteocalcin and urinary N-telopeptide [NTX]), vitamin D nutriture (serum calcium, 25-hydroxyvitamin D [25-OH D] and parathyroid hormone [PTH] concentrations), and intestinal calcium absorption were measured at baseline and at weeks 4 and 12. Dual x-ray absorptiometry (DXA) of the hip and spine was performed to determine bone mineral density (BMD) at baseline and weeks 12 and 24.

RESULTS

The majority of subjects in each group exhibited evidence of vitamin D deficiency at baseline (25-OH D levels<30 ng/mL; 78% and 79% of control and hGH-treated subjects, respectively). Subjects treated with hGH demonstrated a significant increase from baseline in serum osteocalcin levels at 12 weeks (+62%; p<.05). The levels of NTX were increased over time in the hGH-treated group; however, this did not reach statistical significance. Both NTX and osteocalcin remained unchanged in control subjects. BMD of the spine and total hip was unchanged in subjects treated with placebo or hGH at 24 weeks. However, femoral neck BMD was slightly but significantly decreased in the placebo group at this time point but remained unchanged from baseline in the hGH-treated subjects.

CONCLUSIONS

hGH therapy significantly increased markers of bone turnover during the initial 3 months of therapy and stabilized femoral neck bone mass over a 6-month period in patients with severe SBS undergoing intestinal rehabilitation.

Are plasma citrulline and glutamine biomarkers of intestinal absorptive function in patients with short bowel syndrome?

Sensitive biomarkers for intestinal absorptive function would be clinically useful in short bowel syndrome (SBS). Citrulline (Cit) is a product of the metabolism of glutamine (Gln) and derived amino acids by enterocytes. Cit is produced almost exclusively by the gut, which is also a major site of Gln metabolism. The goals of this study were to examine whether plasma Cit and Gln concentrations are biomarkers of residual small intestinal length and nutrient absorptive functions in adult SBS patients followed prospectively. We studied 24 stable adults with severe SBS receiving chronic parenteral nutrition (PN) in a double-blind, randomized trial of individualized dietary modification +/- recombinant human growth hormone (GH). During a baseline week, intestinal absorption studies (% absorption of fluid, kcal, nitrogen, fat, carbohydrate, sodium, phosphorus, and magnesium) were performed and concomitant plasma Cit and Gln concentrations determined. Individualized dietary modification and treatment with subcutaneous injection of placebo (n = 9) or GH (0.1 mg/kg daily x 21 days, then 3 times/week; n = 15) were then begun. PN weaning was initiated after week 4 and continued as tolerated for 24 weeks. Repeat plasma amino acid determination and nutrient absorption studies were performed at weeks 4 and 12. Residual small bowel length at baseline was positively correlated with baseline plasma Cit (r = 0.467; p = .028). However, no significant correlations between absolute Cit or Gln concentrations and the percent absorption of nutrient substrates at any time point were observed. Similarly, no correlation between the change in Cit or GLN concentration and the change in % nutrient absorption was observed (baseline vs weeks 4 and 12, respectively). By weeks 12 and 24, 7 and 13 subjects were weaned completely from PN, respectively. However, baseline plasma Cit or Gln did not predict PN weaning at these time points. We concluded that plasma Cit (but not Gln) concentrations appeared to be an indicator of small intestinal length in adult SBS. However, neither plasma Cit nor Gln was a biomarker for intestinal absorptive function in this cohort of patients with SBS.

Trophic and cytoprotective nutrition for intestinal adaptation, mucosal repair, and barrier function

Intestinal epithelial cell turnover (proliferation, migration, differentiation, and apoptosis) and gut barrier functions are dynamic processes that are markedly affected by nutritional status, the route of feeding, and the adequacy of specific nutrients in the diet. Emerging studies are defining potential therapeutic roles for specific nutrients and diet-derived compounds (including arginine, glutamate, glutamine, glutathione, glycine, vitamin A, zinc, and specific lipids) in gut mucosal turnover, repair, adaptation after massive bowel resection, and barrier function. The role and regulation of endogenous bowel flora in generating short-chain fatty acids from diet-derived fiber and other diet-derived compounds and the effects of these agents on gut function are increasingly being elucidated. Results of these investigations should define new nutritional methods for trophic and cytoprotective effects on the intestine in conditions such as inflammatory bowel disease, malnutrition, and short bowel syndrome.

Severe villus atrophy and chronic malabsorption induced by azathioprine

Azathioprine is commonly prescribed for autoimmune hepatitis and inflammatory bowel disease. An acute gastroenteritis-like syndrome has been ascribed to azathioprine use, but chronic diarrhea has not. We report a patient with autoimmune hepatitis who developed severe small-bowel villus atrophy and chronic diarrhea after azathioprine was initiated (50 mg/day). We present a case report of a patient followed up prospectively. Duodenal mucosal histology and expression of brush border enzyme dipeptidyl peptidase IV and peptide transporter PepT1 messenger RNA levels were determined before and after azathioprine discontinuation. Chronic diarrhea developed several weeks after the initiation of azathioprine and resulted in micronutrient depletion and severe protein-calorie malnutrition, which was unresponsive to oral pancreatic enzyme therapy or a gluten-free diet. Severe malabsorption required parenteral nutrition support for longer than 1.5 years; this was complicated by unstable blood glucose control, acute calculous cholecystitis, catheter sepsis, and severe venous thrombosis. When the temporal association between azathioprine and diarrhea was identified, the drug was tapered while the patient consumed an unrestricted diet. Within 2 weeks after azathioprine was discontinued, diarrhea had completely resolved, and parenteral nutrition was discontinued. Mucosal biopsies obtained before and 4 months after azathioprine discontinuation showed complete reversal of severe duodenal villus atrophy and marked up-regulation of mucosal dipeptidyl peptidase IV and PepT1 messenger RNA. The patient has subsequently maintained normal liver function tests on low-dose prednisone alone, with normal stools and stable nutritional status for longer than 4 years. Azathioprine can induce severe small-bowel villus atrophy, diarrhea, and malabsorption that is reversible with drug discontinuation.

Distribution of the H+/peptide transporter PepT1 in human intestine: up-regulated expression in the colonic mucosa of patients with short-bowel syndrome

BACKGROUND

Intestinal adaptation after massive bowel resection in animal models is characterized by increased gut-mucosal growth and expression of nutrient transporters. Few data about these indexes exist in humans with short-bowel syndrome (SBS).

OBJECTIVE

The objective was to compare small-bowel and colonic mucosal growth and expression of the peptide transporter PepT1 in adults with or without SBS.

DESIGN

Mucosal biopsy specimens were obtained from the small bowel and colon of 33 control subjects with intact intestine and from 13 SBS patients dependent on parenteral nutrition because of chronic malabsorption. Gut-mucosal crypt depth, villus height, and villus width were measured, and expression of PepT1 was determined by Northern blotting, in situ hybridization, and immunohistochemistry.

RESULTS

The indexes of small-bowel and colonic mucosal growth were not significantly different between the 2 groups. PepT1 expression was high in the apical region of duodenal, jejunal, and ileal villus epithelial cells; low in absorptive colonocytes; and not significantly different in the distal small intestine of the 2 groups. However, the abundance of PepT1 mRNA in the colon of SBS patients was more than 5-fold that in control subjects (P < 0.01).

CONCLUSIONS

Gut adaptation in SBS patients does not appear to involve an increase in gut-mucosal crypt depth or villus size. PepT1 is abundant along the small-bowel brush border in humans; expression in the colon indicates that the large intestine has a mechanism for luminal di- and tripeptide transport. Up-regulation of colonic PepT1 in SBS may adaptively improve accrual of malabsorbed di- and tripeptides, independent of changes in the mucosal surface area.

[Parathyroid cysts. Their differential diagnosis from thyroid pathology. A report of 2 cases]

Parathyroid cysts are rare in clinical practice, but, when they appear, they can be mistaken for more common thyroid conditions, that can incidentally be associated with them. We present two cases of parathyroid cysts. One of them was misdiagnosed of thyroid nodule and the other was found in the context of a normo-functioning multinodular goitre. In this last case, the presenting symptoms had raised the suspicion of malignancy. Both of them responded favorably to evacuation of the liquid by means of a puncture-aspiration with a fine needle (PAFN). Our clinical cases show that the diagnosis of parathyroid cyst should be considered in patients with a cervical mass, even if an evident thyroid condition is present. They may be accurately diagnosed by means of PAFN and determining PTH in the cystic liquid, whose characteristics help to predict its side of origin.