Is bile flow reduced in patients with hypothyroidism?

Disturbances in the sphincter of Oddi (SO) function may prevent normal bile flow and thus enhance the probability of common bile duct stone (CBDS) formation. We have previously shown increased prevalence of diagnosed hypothyroidism in CBDS patients, thyroxine (T(4)) -induced inhibition of the SO contractility both in animal and in human experiments ex vivo, and reduced bile flow to duodenum in hypothyroid rats. The aim of the present study was to investigate human biliary dynamics in relation to altered thyroid gland function.

Eight female patients, 1 with diagnosed untreated hypothyroidism and 7 with total thyroidectomy performed due to thyroid cancer, were studied in hypothyroid stage and again after thyroxine replacement therapy in euthyroid stage, with quantitative (99m)Tc HIDA cholescintigraphy (QC), biliary ultrasonography, and serum determinations. Each patient served as her own control in the 2 stages of the study.

In QC, maximal uptake of (99m)Tc HIDA was not changed in hypothyroidism compared to euthyroidism. The first appearance of radioactivity to large bile ducts at the hepatic hilum remained unchanged in the 2 stages of the study. Hepatic clearance of (99m)Tc HIDA was decreased at 45 minutes (28% [11-38] vs 50% [33-54]; P =.028; median and range) and at 60 minutes (55% [28-80] vs 69% [61-79]; P =.028; median and range) and hilum-duodenal transit time increased by 31% compared to euthyroid stage. In US no changes were seen in gall bladder or bile ducts in the 2 stages of the study. Serum hypercholesterolemia was observed in the hypothyroid stage.

We conclude that hypothyroidism may result in delayed emptying of the biliary tract, as studied with QC. In addition to the changes in bile composition and excretion rate suggested before to take place in hypothyroidism, according to the present study changes in biliary emptying also may be included in the probable causes for the increased prevalence of CBDS in hypothyroidism. This may be due to the absence of the prorelaxing effect of thyroxine on SO, which we have shown before to exist ex vivo.