Anorectal physiology and transit in patients with disorders of thyroid metabolism

Background: Data on anorectal physiology in patients with disordered thyroi d metabolism are lacking. This prospective study was performed to evaluate anorectal physiology in patients with either hyperthyroidism and diarrhoea, or hypothyroidism and constipation in order to assess slow transit in hypo thyroid patients. Methods: Thirty patients with hypothyroidism and constipation (24 females, median age 59 years, range 23-80) and 20 patients with hyperthyroidism and diarrhoea (12 females, median age 46 years, range 36-62) were evaluated by anal manometry, rectal balloon sensation and whole-gut transit markers. Dat a were compared with anorectal physiology and whole-gut transit in 22 healt hy controls (13 females, median age 51 years, range 24-65). Results: In the hypothyroid patients, maximum resting pressure (MRP) and ma ximum squeeze pressure (MSP) were similar to controls (patients, median MRP 55 mmHg (18-98); controls, median MRP 41 mmHg (20-105) and patients, media n MSP 83 mmHg (39-400); controls, median MSP 88 mmHg (30-230); P>0.05 for b oth resting and squeeze pressures). In hyperthyroid patients, median MRP an d MSP were significantly lower than controls (patients, MRP 33 mmHg (8-69); controls A MRP 31 mmHg (20-105) P=0.04 and patients, MSP 60 mmHg (26-104); controls, MSP 88 mmHg (30-230); P=0.03). Threshold sensation for impending evacuation in hypothyroid patients was significantly higher than controls, while in hyperthyroid patients, threshold sensation was significantly lowe r compared with controls. Maximum tolerable rectal volumes in hypothyroid p atients was significantly lower compared with controls, while no significan t difference was found between maximum tolerable rectal volumes in hyperthy roid patients and controls. Prevalence of delayed whole-gut transit in both hypothyroid and hyperthyroid patients was similar to controls. Furthermore , 33% of hypothyroid patients and 40% of hyperthyroid patients experienced symptoms of bowel dysfunction prior to the onset of their thyroid disorder. Conclusions: Patients with altered thyroid function and bowel dysfunction d emonstrated abnormalities of anal manometry and rectal sensation.