Hypothyroidism improves random-pattern skin flap survival in rats

Abstract

BackgroundThe protective effect of hypothyroidism against ischemic or toxic conditions has been shown in various tissues. We investigated the effect of propylthiouracil (PTU)/methimazole (MMI)-induced hypothyroidism and acute local effect of MMI on the outcome of lethal ischemia in random-pattern skin flaps. Materials and methodsDorsal flaps with caudal pedicles were elevated at midline and flap survival was measured at the seventh day after surgery. The first group, as control, received 1 mL of 0.9% saline solution in the flap before flap elevation. In groups 2 and 3, hypothyroidism was induced by administration of either PTU 0.05% or MMI 0.04% in drinking water. The next four groups received local injections of MMI (10, 20, 50, or 100 μg/flap) before flap elevation. Local PTU injection was ignored due to insolubility of the agent. ResultsHypothyroidism was induced in chronic PTU- and MMI-treated groups, and animals in these groups showed significant increase in their flap survival, compared to control euthyroid rats (79.47% ± 10.49% and 75.48% ± 12.93% versus 52.26% ± 5.75%, respectively, P < 0.01). Acute local treatment of skin flaps with MMI failed to significantly affect the flap survival. ConclusionThis study demonstrates for the first time that hypothyroidism improves survival of random-pattern skin flaps in rats.