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Partial Defect of Iodide Trapping Mechanism in Two Siblings with Congenital Goiter and Hypothyroidism

1972; Oxford University Press; Volume: 35; Issue: 3 Linguagem: Inglês

10.1210/jcem-35-3-370

1945-7197

Geraldo Medeiros‐Neto, W Bloise, A. B. ULHOACINTRA,

Ion channel regulation and function

Two siblings, a 23-yr-old woman and a 34-yr-old man, with congenital goiter and hypothyroidism were referred to the thyroid clinic for evaluation. They were on thyroid extract since early childhood and attained normal growth but were mentally retarded. Inbreedings were noted in the family pedigree but no cases of goiter were reported. The BMR was low for both patients and PBI was 1.0 μg and 2.2 μg/100 ml, respectively. T4-I was 1.0 μg and 1.8 μg/100 ml. The perchlorate test was negative. The TRC test was repeatedly negative. The RAI uptake was 3.5% and 6.0% at 24 hr with no response to TSH. Plasma chromatography of iodinated compounds disclosed only iodide and iodoproteins. Traces of T3 + T4 were present in one sairrole. Plasma TSH was very high in both patients. The resting mixed saliva/plasma ratio at 2, 4 and 6 hr after a iv dose of 131I were, respectively, 7.2 and 5.9, 8.7 and 5.9, 7.9 and 6.7 for HCR, and JFCR (normal controls: 27.7–64.3). The gastric juice/plasma ratio was 5.2 and 5.0 seven hr after the tracer dose (normal controls: 22.0). There was no improvement either in the saliva/plasma or the gastric juice/plasma ratio after 30 days of daily T3 (100 μg) administration. The ratio of iodine between cerebrospinal fluid and plasma was respectively 0.072 (HCR) and 0.128 (JFCR) (normal controls: 0.009–0). The thyroid tissue contained only small follicles with scant or no colloid. Cord-like structures apparently devoid of follicular lumen were also seen. There were numerous abnormalities at the cellular level. The 127I content of the thyroid tissue was only 4.59 (HCR) and 8.59 μg/g (JFCR) of thyroid homogenate. Chromatography of the hydrolyzed homogenate revealed only traces of T3 + T4) with a high iodotyrosine/iodothyronine ratio. Estimated by gel filtration approximately only 10% and 26% of the total soluble iodo-protein was identified as thyroglobulin. More than 60% of the total iodine (127I and 125I) was found within an easily sedimentable particulate iodo-protein. The thyroid/medium (T/M) ratio of iodide in incubated slices of the gland was 1.74 and 1.87 (normal controls: 7.2) and there was no improvement in the T/M ratio with addition of bovine TSH to the medium.