Effects of Thyroid Hormone on the Adaptation in Short Bowel Syndrome

Thyroid dysfunction in infants with severe intestinal insufficiency: a case series

OBJECTIVE

The aim of this study was to describe the status of thyroid function in infants with severe intestinal dysfunction.

CASE DESCRIPTION

A retrospective study was conducted in a tertiary neonatal intensive care center, including newborns and infants with severe intestinal dysfunction, hospitalized between 2015 and 2020. From the medical records, the following data were collected: gestational age, birth weight, underlying pathology that led to intestinal dysfunction, hospital stay, presence of thyroid dysfunction, age from the onset of thyroid dysfunction, initial and maximum dose of levothyroxine replacement, and levothyroxine administration route and outcome. Seven children (0.76% of 914 hospitalizations) developed severe intestinal insufficiency: vanishing gastroschisis (42.9%), Berdon syndrome (28.5%), apple peel (14.3%), and OIES syndrome (14.3%) - omphalocele, exstrophy of cloaca, imperforate anus, and spina bifida. The mean gestational age was 33.3±1.6 weeks, the mean birth weight was 2,113.9±370.9 g, the median hospitalization was 420 days, and mortality was 42.9%. Of these seven cases, four (57.1%) presented thyroid dysfunction, evaluated by blood hormone dosages and the dose of levothyroxine replacement ranged from 25 to 100 μg/day, administered by gastric or rectal route.

COMMENTS

This series of cases draws attention to thyroid dysfunction (hypothyroidism) in children with severe intestinal insufficiency receiving exclusive parenteral nutrition for a prolonged period, whose etiology is iodine deficiency, because, in Brazil, micronutrient solutions added to parenteral nutrition do not contain iodine.

Novel Therapeutic Approaches for Mitigating Complications in Short Bowel Syndrome

Short bowel syndrome (SBS) is a particularly serious condition in which the small intestine does not absorb sufficient nutrients for biological needs, resulting in severe illness and potentially death if not treated. Given the important role of the gut in many signaling cascades throughout the body, SBS results in disruption of many pathways and imbalances in various hormones. Due to the inability to meet sufficient nutritional needs, an intravenous form of nutrition, total parental nutrition (TPN), is administered. However, TPN presents difficulties such as severe liver injury and altered signaling secondary to the continued lack of luminal contents. This manuscript aims to summarize relevant studies into the systemic effects of TPN on systems such as the gut-brain, gut-lung, and gut-liver axis, as well as present novel therapeutics currently under use or investigation as mitigation strategies for TPN induced injury.

Hypothyroidism associated with short bowel syndrome in children: a report of six cases

Short bowel syndrome (SBS) is the leading cause of intestinal failure in children, a condition of absence of sufficient bowel to meet the nutritional and metabolic needs of a growing individual. The treatment of patients in this situation is based on the association of parenteral and enteral nutrition for prolonged periods of time until intestinal rehabilitation occurs with complete enteral nutrition autonomy. Six consecutive cases of children with SBS (residual intestinal length of 5 cm to 75 cm) were managed with this program and were diagnosed with associated hypothyroidism during the treatment (ages at the diagnosis 5 months to 12 years). All patients were successfully treated with oral hormone reposition therapy and in one patient, the replacement was performed via rectal enemas due to a complete absence of small bowel. Although iodine deficiency associated to long-term parenteral nutrition is a well-known condition, this is the first report in the literature about an expressive number of patients with hypothyroidism detected in patients with SBS during the prolonged treatment for intestinal rehabilitation.

Treatment of congenital hypothyroidism in a newborn with malabsorption after subtotal ileum resection

Congenital hypothyroidism requires prompt treatment to prevent adverse health outcomes. Poor intestinal levothyroxine absorption can complicate management. We present a case of a term female newborn with necrotizing enterocolitis (NEC) requiring subtotal ileum resection. Congenital hypothyroidism was diagnosed by newborn screening. Treatment was complicated by intestinal malabsorption of levothyroxine. Intravenous levothyroxine substitution restored euthyroidism and supraphysiologic PO doses subsequently maintained a euthyroid state. After several months, the required levothyroxine dose was weaned down to typical recommended dosing. In conclusion, small bowel resection secondary to NEC may lead to malabsorption of oral levothyroxine. An intravenous levothyroxine dose of approximately 50% typical PO dosing is effective in providing rapid normalization of free T4 and TSH. High PO doses may be required to maintain euthyroidism. Close thyroid function monitoring and immediate therapy adjustment are essential as the individual absorption may vary widely. Normal absorption levels may be regained due to adaption of the neonatal intestines.

Effects of thyroid hormone supplementation on anastomotic healing after segmental colonic resection

BACKGROUND

Alterations of thyroid hormones in colorectal surgery were previously studied. The aim of the present study was to determine the effects of triiodothyronine (T3) supplementation on anastomotic healing after segmental colectomy.

MATERIAL AND METHODS

Thirty male Wistar albino rats were divided into sham (n = 6), control (n = 12), and experimental (n = 12) groups. Sham group rats were immediately sacrificed after segmental colonic resection. Control and experimental group rats underwent resection and anastomosis. Experimental group rats received a single dose of T3 (400 μg/100 g) in postoperative day 1. Half of both control and experimental group rats were sacrificed on postoperative d 3 and the remaining half were sacrificed on postoperative d 7. Hydroxiproline (HP), myeloperoxidase (MPO), thyroid stimulating hormone (TSH), free T3 (FT3), and free thyroxine (FT4) levels, bursting pressure, and histologic analyses of the anastomotic segments were compared.

RESULTS

FT3 levels significantly decreased in control groups rats compared with the sham group (P < 0.01). However, T3 hormone given rats had no decline in FT3 levels. Anastomotic bursting pressure was significantly higher in the experimental group rats on postoperative d 7 (P = 0.015). Histopathologic analyses of the anastomotic segments determined significantly more severe edema and necrosis in control group rats (P < 0.05). Collagen deposition in the anastomotic tissue was significantly higher in experimental group rats on postoperative d 7 (P = 0.015).

CONCLUSION

Anastomosis after colon resection is associated with decreased FT3 level. T3 supplementation ameliorates the reduction in FT3 and seems to provide constructive therapeutic effects on anastomotic healing.

Growth factors: possible roles for clinical management of the short bowel syndrome

The structural and functional changes during intestinal adaptation are necessary to compensate for the sudden loss of digestive and absorptive capacity after massive intestinal resection. When the adaptive response is inadequate, short bowel syndrome (SBS) ensues and patients are left with the requirement for parenteral nutrition and its associated morbidities. Several hormones have been studied as potential enhancers of the adaptation process. The effects of growth hormone, insulin-like growth factor-1, epidermal growth factor, and glucagon-like peptide 2 on adaptation have been studied extensively in animal models. In addition, growth hormone and glucagon-like peptide 2 have shown promise for the treatment of SBS in clinical trials in human beings. Several lesser studied hormones, including leptin, corticosteroids, thyroxine, testosterone, and estradiol, are also discussed.