Diiodotyrosine (DIT) is a precursor of thyroid hormone and results from iodization of monoiodotyrosine at the other meta- position on the phenol ring. DIT is a modulator of thyroid peroxidase.[1] When combined with monoiodotyrosine in the colloid of the thyroid follicle, triiodothyronine is formed. Two molecules of DIT combine to make thyroxine. Urinary 3,5-diiodotyrosine (DIT) and thyronine (T0) excretion was investigated in 18 patients with chronic renal disease. In accord with previous findings serum T4 and thyroid hormone binding proteins measured in 17 patients were in the low or normal range. Urinary albumin excretion was elevated in all 18 and T4 binding prealbumin (TBPA) in 15 of the 18.In contrast urinary DIT excretion was significantly elevated in renal patients compared with normal subjects. Possible sources of the increased DIT are discussed.
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