Endocrine Abstracts (2017) 49 EP810 | DOI: 10.1530/endoabs.49.EP810

Differences in calcium and thyroid homeostasis and thyroid volume after bariatric surgery

İffet Dagdelen Duran1, Nese Ersöz Gülçelik2, Dilek Berker1 & Serdar Güler1

1Ankara Numune Education and Research Hospital, Department of Endocrinology and Metabolic Diseases, Ankara, Turkey; 2Ankara Education and Research Hospital, Department of Endocrinology and Metabolic Diseases, Ankara, Turkey.

Introduction: Bariatric surgery would end up with great alterations in homeostatic measures such as glucose and lipid metabolism and hormonal regulation, which of all are interweaved with some number of ways to each other. The hormonal modulation extands along a wide span starting from the change in gastrointestinal peptides, to the effect in insulin and other nutrient metabolism regulatory hormones and even the hormones establishing thyroid and calcium homeostasis. Secondary hyperparathyroidism is a common finding associated with decreased nutrient, mineral and vitamin D absorption after gut lumenal loss due to bariatric surgery. Meanwhile when the adaptation of thyrotropin (TSH) and free t4 (fT4) level shows variance among studies, in fact TSH frequently was reported to decrease. Free t3 (fT3) was constantly shown to decrease, used to be correlated with dysfunction in deiodination. The thyroid volume would also be a candidate of other parameter that is expected to change over postsurgical period.

Materials and Methods: We recruited 67 morbidly obese patients planned to have bariatric surgery. All the subjects were recorded for their body weight, BMI, metformin, insulin and levothyroxine(LT4) usage and if used dosage of the drug before the operation. The patients were examined with hormonal [parathormon(PTH), 25-oh-vitamin d3(25vitD3), TSH, fT3, fT4 and biochemical tests [calcium(Ca), ionized Ca(iCa), phosphorus(P), 24 hour(h) urinary Ca]. Thyroid ultrasonography (USG) were performed by one same practitioner and the diameters of each lobe was given as axbxc(cm). The volume of each lobe was calculated with axbxcx0.524 (cm3), and total thyroid volume with addition of right to left lobe volume. The number of nodules and the size of largest nodule were also recorded. The antropometric measures, drug consumption data, laboratory tests and thyroid USG were repeated after 12 month of surgery.

Results: The mean age of patients was 41.5±9.6 year. 58 (86.5%) subjects were female, while 9(13.5%) were male. After 12 month of surgical approach, mean body weight decreased from 120.3±4.1 kg to 85.4±3.3 kg (P:0.00), BMI from 47.8±1.4 kg/m2 to 34.0±1.2 kg/m2 (P:0.00), TSH from 2.3±0.2 to 1.1±0.2 μIU/ml (P:0.00), fT4 from 1.0±0.0 to 0.5±0.0 ng/dl (P:0.00), fT3 from 2.5±0.1 to 1.3±0.1 pg/ml (P:0.00), PTH from 48.6±4.7 to 24.4±4.4 pg/ml (P:0.00), Ca from 8.0±0.4 to 5.0±0.6 mg/dl (P:0.00), and thyroid volume from 9.6±2.2 to 4.0±0.8 cm3 (P:0.022) significantly. Levothyroxine and insulin requirement decreased after operation nonsignificantly. 25vitD3 increased, 24 h urinary Ca decreased again nonsignificantly.

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