[Predisposition to thyroid autoimmune diseases]

OBJECTIVES

Genetic predisposition is required for the expression of thyroid autoimmune disorder addition to the immune dysfunction and the environmental factors.

METHODS

In order to evaluate the role of this genetic factor, we reported the results of immunological and hormonal investigations of 62 members (TD), belonging to a large Akr family, who are related to 40 patients with Graves' disease or Hashimoto's thyroiditis.

RESULTS

The hormonal analyses showed that 19 subjects exhibited an infraclinical hypothyroidism, subdivided into 7 members with pathological rates of TSH evocative of thyroid insufficiency and 12 others with compensative thyroid insufficiency. Seventeen subjects of the Akr family who had solely antithyroid autoantibodies were considered as potential candidates to develop thyroid autoimmune diseases. The clinical follow-up, during two years, confirmed the diagnosis of Hashimoto's thyroiditis in 3 members among 19 subjects with infraclinical hypothyroidism (TD05, TD28 and TD54) and in only 1 member out of the 17 potential candidates (TD03).

CONCLUSION

Our results showed that a serological study of hormones and/or autoantibodies directed against thyroid antigens, could allow the detection of predisposed subjects to develop a thyroid autoimmune pathology. The Akr family seems to be suitable for the study of the localization of susceptibility genes to TAID.

Maternal thyroid hormones in Japanese quail eggs and their influence on embryonic development

We addressed the relationship between the thyroid status of hens and the thyroid hormone content of their eggs, as well as the influences of egg hormones on embryonic development. Methods for measuring thyroid hormones in egg yolk were verified by demonstrating consistency in the recovery of yolk thyroid hormones following a methanol/chloroform extraction and in the measurement of thyroid hormones by RIA for a range of hormone concentrations in yolk extracts. Untreated hens produced eggs with yolk thyroxine (T4) concentrations that were low relative to plasma T4, but yolk triiodothyronine (T3) concentrations comparable to those of plasma. Hens dosed twice daily with T4 (1 or 3x the daily thyroid secretion rate, TSR, of T4 per dose) had significantly higher plasma and egg yolk T4 concentrations than did control hens dosed with saline. In general, the T4 concentration of egg yolk varied with the thyroid status of the hen. When the relationship between each hen's plasma T4 and the yolk T4 concentration of her eggs was examined, hens appeared to regulate T4 deposition into yolk at "levels" characteristic of the "levels" of thyroid status produced by the different doses of T4. Embryonic pelvic cartilage, a thyroid hormone-responsive tissue, showed enhanced growth and differentiation in embryos from eggs of hens given the highest dose of T4. Specifically, alkaline phosphatase activity (a marker of differentiation) and pelvic cartilage wet and dry weights were significantly greater in embryos from high T4 eggs (hens on the 3x TSR dose) than those in controls. However, embryos from high T4 eggs did not differ in general body growth (body weight, length, and general morphology) or hatchability compared to controls. In a single T3 experiment, hens were dosed twice daily with 1 microg T3. The embryos from eggs of these hens had accelerated differentiation/maturation of pelvic cartilages (sampled at Day 12) compared to those from control eggs; body growth did not differ from that of controls.

Antenatal diagnosis and treatment of fetal hypothyroidism. A report of two cases

Fetal goiter in the presence of maternal Graves' disease can signify either hyperthyroidism or hypothyroidism in the fetus. Two patients with Graves' disease taking propylthiouracil were found to have a fetal goiter on a prenatal sonogram. Fetal blood sampling identified hypothyroidism in both instances. Administration of intraamniotic thyroxine resulted in rapid resolution of the goiter, normalization of subsequent fetal thyroid studies, and delivery of a euthyroid fetus. Cordocentesis allows accurate diagnosis and follow-up of fetal thyroid dysfunction and prompt initiation of appropriate therapy.

A micromethod for quantitative determination of iodoamino acids in thyroglobulin

We describe a new method for quantification of iodoamino acids after enzymatic hydrolysis of thyroglobulin. The procedure involves separation of monoiodotyrosine (MIT), di-iodotyrosine, tri-iodothyronine and thyroxine by reverse phase HPLC with a Vydac C18 stationary phase and a mobile phase of water-acetonitrile-acetic acid. The separation is monitored by sensitive spectrophotometric detection through a 96-well microplate system based on the catalytic Sandell-Kolthoff reaction of iodide on the oxidation of arsenic(III) by cerium(IV). This new microassay is particularly convenient because of its high sensitivity and its rapidity (less than 2 h). It can detect 1 pmol MIT and 0.5 pmol of the other three iodoamino acids with a recovery higher than 96%. Moreover, the 96-well microplate system allows many samples to be tested simultaneously and avoids the use of radiolabeled iodine.

[Predictive value of the measurement of iodothyronines in the prognosis of patients with severe nonthyroidal illness]

PURPOSE

In order to find prognostic parameters in patients with severe diseases, we analyzed sequentially the levels of thyroid hormones.

METHODS

We measured iodothyronines (T3, T4 and rT3) in 42 patients before the admission and after the discharge in an intensive care unit. In addition, we also measured the iodothyronines in other 17 patients after the discharge.

RESULTS

Comparing the group of good outcome with the patients who died, we observed in the former group initial normal T4 levels in 76% of the patients, which were maintained in 65% of them during hospitalization and in 70% of them at the time of delivery from the intensive care unit. Patients who died, however, presented initial low T4 levels in 56% of them, decreasing values in 95% of them during hospitalization and low levels in 81% of patients at the last dosage. The combined profile of T3 and T4 also differentiated good and bad outcome.

CONCLUSION

We suggest that serial analysis of serum levels of thyroid hormones may help the evaluation of critical care patients.

Evidence for circadian variations of thyroid hormone concentrations and type II 5'-iodothyronine deiodinase activity in the rat central nervous system

The 24-h patterns of tissue thyroid hormone concentrations and type II 5'- and type III 5-iodothyronine deiodinase (5'D-II and 5D-III, respectively) activities were determined at 4-h intervals in different brain regions of male euthyroid rats entrained to a regular 12-h light/12-h dark cycle (lights on at 6:00 a.m.). Activity of 5'D-II, which catalyzes the intracellular conversion of thyroxine (T4) to 3,3',5-triiodo-L-thyronine (T3) in the CNS, and the tissue concentrations of both T4 and T3 exhibited significant daily variations in all brain regions examined. Periodic regression analysis revealed significant circadian rhythms with amplitudes ranging from 9 to 23% (for T3) and from 15 to 40% (for T4 and 5'D-II) of the daily mean value. 5'D-II activity showed a marked nocturnal increase (1.3-2.1-fold vs. daytime basal value), with a maximum at the end of the dark period and a minimum between noon and 4:00 p.m. 5D-III did not exhibit circadian patterns of variation in any of the brain tissues investigated. Our results disclose circadian rhythms of 5'D-II activity and thyroid hormone concentrations in discrete brain regions of rats entrained to a regular 12:12-h light-dark cycle and reveal that, in the rat CNS, T3 biosynthesis is activated during the dark phase of the photoperiod. For all parameters under investigation, the patterns of variation observed were in part regionally specific, indicating that different regulatory mechanisms may be involved in generating the observed rhythms.

Pityriasis rotunda: a survey of 42 cases observed in Sardinia, Italy

BACKGROUND

Pityriasis rotunda (PR) is an uncommon dermatosis characterized by multiple, round or oval, sharply demarcated scaling patches that are dyschromic and asymptomatic. It has been described in Japanese and in blacks, usually in association with certain infective or malignant systemic diseases.

OBJECTIVE

The aim of this study is to further clarify this rare entity which in Italy seems to be confined to the island of Sardinia.

METHODS

We studied 42 Sardinian patients, 22 males and 20 females, in an age range of 3-32 years. In 29 cases, the disease involved more than one family member. The patients were observed in Cagliari, the capital city of Sardinia.

RESULTS

Bacterial, viral and fungal investigation yielded negative results. Haematochemical and immunological examination and thyroid, hypophyseal and adrenal hormones did not reveal any alterations. No systemic pathologies were found associated with the disease.

CONCLUSIONS

The cases studied by us and those previously reported seem to indicate the presence of two distinct types of PR with significant prognostic differences.

Effects of thyroid hormone on the androgenic expression of KAP gene in mouse kidney

The kidney androgen-regulated protein (KAP) gene exhibits a cell-specific hormonal regulation of its expression in the epithelial cells of proximal tubules of mouse kidney, where T3 is required for constitutive expression in the straight segments and androgens for expression in the convoluted ones. By using different models of hypothyroidism, we demonstrate that maximal androgen-mediated induction of the gene depends on thyroid hormone as well. This constitutes a specific event, since vitamin D3 cannot mimic the effects of T3, albeit their remarkable functional relationship. It is also shown that while congenital hypothyroid hyt/hyt male mice, exposed to maternal T3 in the gestational period, exhibit diminished but existent androgen-dependent cortical responses, mice exposed to goitrogens during gestation and postnatally are unable to express the gene even at postnatal day ninety. Impairment of KAP cortical expression in hypothyroid animals does not correlate with lower levels of androgens or androgen receptor expression.

An update on diagnostic methods in the investigation of diseases of the thyroid

Iodine deficiency and iodine-deficiency disorders continue to be problems in several parts of Europe, requiring further improvements in the techniques employed in thyroid diagnosis, and particularly in the early diagnosis and risk assessment of autonomously functioning thyroid tissue. For the latter purpose, scintigraphy with technetium-99m pertechnetate under exogenous or endogenous thyroid-stimulating hormone (TSH) suppression provides the best results. Significant methodological improvements in laboratory tests have resulted from the application of new luminescent techniques and gene technology to thyroid function tests. Especially TSH measurement using second- or third-generation assays ensures diagnostic accuracy, so that the thyrotropin-releasing hormone (TRH) test is now almost always unnecessary. The differentiation of blocking and stimulating TSH receptor antibodies is relevant when discrepant results are obtained with respect to thyroid function. Determination of glycosaminoglycans in urine may become a helpful tool in the follow-up of endocrine ophthalmopathy. Some new imaging agents have recently been applied in the scintigraphy of thyroid diseases, such as octreotide, or in thyroid diagnosis, such as fluorodeoxyglucose. Both improve the detectability of metastases of thyroid cancer, especially if the radioiodine scan is negative.

Histological studies of atrazine toxicity on the thyroid gland in rats

Little is known about the toxic activity of the atrazine (a herbicide, commonly used in agricultural production) on the thyroid gland. In this study the compound was administered orally in female albino rats at sublethal exposure equivalent to 0.2 LD50 doses for 6 and 12 days. At termination of dosing the anesthetized animals were killed and blood was drawn for the determination of serum triiodothyronine (T3) and thyroxin (T4). A dose-dependent decrease of serum T3 concentration was observed in all the groups (control: 0.57 nmol-L-1; 6 days: 0.35 nmol-L-1; 12 days: 0.21 nmol-L-1). The thyroid gland was examined light-microscopically. Bouin's solution-fixed thyroids were embedded in paraffin and sections cut at 6 microns, stained separately with toluidine blue according to Slinchenko's method. Histologically in experimental groups epithelium featured small cuboidal cells and occasional structures of the follicles confluence within epitheliomers. A dose-dependent changes of the following parameters were observed: (a) increasing of number of follicle-building thyroid cells; (b) increasing of follicular volume; (c) decreasing of nucleus volume. Investigation of the whole population of thyroid mast cells disclosed no change in degranulation intensity. By contrast, degranulation intensity was decreased in perifollicular mast cells from groups treated with atrazine in dose-dependent manner. There are no changes observed in degranulation of stromal mast cells. These results suggesting that differences in response to the atrazine might account for an aspect of the functional heterogeneity within the rat thyroid mast cell population.

Thyroid hormone deiodination pathways in brain and liver of rainbow trout, Oncorhynchus mykiss

Outer-ring (5') deiodination (ORD) and inner-ring (5) deiodination (IRD) of L-thyroxine (T4) and 3,5,3'-triiodo-L-thyronine (T3) were studied in whole-brain microsomes of rainbow trout and compared with liver deiodination. Brain T4ORD activity (apparent Km = 1.2-2.5 nM; V(max) = 0.10-0.14 pmol/hr/mg microsomal protein) was less than T4IRD activity (apparent Km = 4.9; V(max) = 0.32) and T3IRD activity (apparent Km = 5.2-5.4; V(max) = 1.1-2.0); T3ORD activity was negligible. All three brain deiodinase pathways shared the following properties: pH optima between 7.0 and 7.3, activity enhanced by dithiothreitol (10 mM), weak inhibition by 6-n-propyl-2-thiouracil and iodoacetate, but stronger inhibition by aurothioglucose. Based on competitive inhibition, the substrate preference for brain T4ORD was T4 = tetraiodothyroacetic acid (TETRAC) > 3,3',5'-triiodo-L-thyronine (rT3) > 3,5,3'-triiodothyroacetic acid (TRIAC) >> T3 > 3,5-diiodo-L-thyronine (3,5-T2). A comparable substrate preference profile was obtained for liver T4ORD (Km 1 nM). Both T4IRD and T3IRD in brain had similar substrate preference profiles (rT3 > 3,5-T2 > T4 > T3) which differed from that of T4ORD. Negligible T4IRD and T3IRD activities existed in liver. We conclude that for rainbow trout (i) T4ORD systems in brain and liver are similar, and consistent with a common enzyme that does not match exactly either mammalian type I or II deiodinases, (ii) brain T4IRD and T3IRD enzymes share several common properties, and correspond functionally to the mammalian type III deiodinase, and (iii) under normal physiological conditions the predominant deiodinase pathways in brain (T4IRD and T3IRD) are poised toward T4 and T3 degradation, while that in liver (T4ORD) is poised toward T3 generation.

Identification of thyroid hormone conjugates produced by isolated hepatocytes and excreted in bile of rainbow trout, Oncorhynchus mykiss

We studied thyroid hormone (TH) conjugation in fasted trout by incubating isolated hepatocytes with either [125I]T4 or [125I]T3, and by analyzing bile from trout injected with either [125I]T4 or [125I]T3. Glucuronide conjugates were identified by hydrolysis with beta-glucuronidase and sulfate conjugates by acid solvolysis with ethyl acetate/trifluoroacetic acid (1%). We used Sephadex LH-20 chromatography to concentrate the conjugate fractions from hepatocyte incubates prior to HPLC analysis. Glucuronide conjugates of T4 and T3 were produced in vitro and glucuronides of T4, T3, and 3,3'-T2 were found in vivo. Sulfation of T4 occurred in vitro and in vivo. T3 sulfation was not established in vitro, but sulfate conjugates of T3 and T2 were found in bile. Significant proportions of unconjugated T4 and T3 also occurred in the bile. We conclude that (i) as in other vertebrates, iodothyronines undergo hepatic glucuronidation and are excreted as such in the bile, (ii) T4 and T3 undergo sulfation, and in contrast to mammals, are excreted in significant amounts in the bile, (iii) 3,3'-T2, a prominent deiodination product of T3, is excreted as both glucuronide and sulfate conjugates, and (iv) the isolated hepatocyte system is appropriate for studying aspects of TH metabolism in trout.

[Thyrotropin and thyroid hormones in human saliva before and after the taking of food]

Saliva of parotid or submaxillary and sublingual glands and venous blood were collected using the Leshly-Krasnogorskiĭ's capsules in young men volunteers on an empty stomach immediately and in 30 minutes after meal. Contents of thyrothropin (I), 3-iodinethyronin (II) and thyroxin (III) were analyzed In saliva and serum. Saliva secretion was stimulated by spilled drops of 3% citric acid solution on tongue. It was shown that I, II and III were habitual in saliva and their concentration in saliva were increased after meal. More significant postprandial increasing of hormones were seen in saliva of parotid gland than in mixed saliva of submaxillary and sublingual glands. As can be justified by quick effect of meal secretion of hormones in saliva has reflex nature. The mechanisms of secretion and resources of hormones in saliva are discussed.

Amniotic and allantoic fluid concentrations of thyroxine, 3,3',5'-tri-iodothyronine, 3,3'-di-iodothyronine and 3',5'-di-iodothyronine in the pig during the period of gestation

Thyroxine (T4), 3,3',5'-tri-iodothyronine (reverse T3; rT3) and di-iodothyronines (3,3'-T2 and 3',5'-T2) were measured in pig amniotic fluid (AF) and allantoic fluid (Al) between 32 and 113 days of normal pregnancy. Low but measurable quantities of T4 in AF and Al (2.1 +/- 0.3 and 3.2 +/- 0.5 nmol/l respectively) were found before the onset of fetal thyroid gland function, which indicates the maternal source of T4. The presence of rT3 (55.8 +/- 4.1 pmol/l in AF and 49.8 +/- 5.3 pmol/l in Al), 3,3'-T2 (45.5 +/- 0.6 pmol/l in AF and 49.2 +/- 9.2 pmol/l in Al) and 3',5'-T2 (20.8 +/- 2.6 pmol/l in AF and 24.0 +/- 2.2 pmol/l in Al) may be attributed to the monodeiodinase system already active in fetal pig tissues in early pregnancy, as demonstrated previously. T3 concentration was undetectable in both AF and Al. An approximately twofold increase in the levels of T4, rT3 and T2s in AF and Al at mid-gestation was observed. T4 and rT3 in AF showed a positive correlation with protein concentrations. AF rT3 concentration (but not T4) correlated with rT3 in the cord and maternal serum. The 3,3'-T2 and 3',5'-T2 in AF and Al showed parallel changes to rT3, while the rT3/3,3'-T2 and rT3/3',5'-T2 molar ratios remained constant. T4 concentrations in AF and Al were markedly lower than in corresponding maternal and fetal serum; the rT3 concentration in Al was equal to that in AF and two to four times lower than in fetal serum. In spite of differences between serum hormone patterns in the pig and human near term, iodothyronine concentrations in AF showed some similarities, mainly the following: undetectable T3, a strong correlation between rT3, T4 and AF total protein and the presence of 3,3'-T2 and 3',5'-T2 in measurable levels. Comparative data for Al, except the ones in the present study in the pig, are not available.

[Thyroid and AIDS]

Two types of thyroid biochemical abnormalities (TBA) are observed in AIDS. The unspecific TBA are similar to TBA reported in the Euthyroid Sick Syndrome. An increased serum TBG of unknown origin and a decreased circulating rT3 are the most specific TBA of AIDS. The latter abnormality may be in relation with an elevated level of TNF. The frequency of serum antithyroid antibodies seems higher than in control groups. Opportunistic infections of the thyroid gland or destruction of the thyroid by Kaposi's sarcoma are also reported in AIDS.

Acetylcholine receptor antibodies in patients with Graves' ophthalmopathy

OBJECTIVES

To determine the frequency and clinical correlates of acetylcholine receptor (AChR) antibody seropositivity in patients with Graves' ophthalmopathy.

MATERIALS AND METHODS

Fifty consecutive new patients with Graves' ophthalmopathy diagnosed in an outpatient neuro-ophthalmology practice underwent determination of AChR-binding antibodies. Clinical and biochemical thyroid variables were compared between seropositive and seronegative patients. Clinical variables included age, sex, thyroid disorder, and duration and course of illness. Biochemical variables included thyroid hormone levels and thyroid antibodies. Seropositive patients were followed clinically to identify signs of myasthenia gravis.

RESULTS

Four of 50 (8%) patients had definitely elevated levels of AChR-binding antibodies. No obvious differences existed between the seropositive and seronegative groups in regards to age, sex, underlying thyroid disorder, biochemical thyroid state, presence of thyroid antibodies, or duration and course of their disease. None of the four seropositive patients developed signs of myasthenia gravis during the median follow-up period of 4.5 years.

CONCLUSION

AChR-binding antibody seropositivity occurs in a small proportion of patients with Graves' ophthalmopathy but, by itself, does not necessarily identify an individual with concurrent myasthenia gravis or an individual at risk to develop myasthenia gravis.

The effects of desipramine on thyroid hormone concentrations in rat brain

The effects of the antidepressant desipramine on the tissue concentrations of thyroxine and triiodothyronine in 9 different regions of the brain and also in the pituitary and liver were investigated in male rats. The investigations were carried out at three different times of the light/dark cycle: 5 a.m., 1 p.m. and 11 p.m. After fourteen days' treatment with 20 mg/kg/day desipramine by gavage the concentrations of triiodothyronine in the frontal and parieto-occipital cortex were significantly higher than in the saline-treated controls, those in the hippocampus lower and those in the 6 remaining brain regions the same. In 8 areas of the brain the concentrations of thyroxine were lower in the desipramine-treated rats and the tissue ratios of triiodothyronine to thyroxine were enhanced in 6 regions. These effects are most likely the result of the action of desipramine on the activity of the isoenzyme 5'II deiodinase. This enzyme catalyzes the deiodination of thyroxine to triiodothyronine in rat brain and its activity has recently been reported to be enhanced by desipramine. The observed effects were dose-dependent and also strongly dependent upon the time within the 24 h light/dark cycle at which the hormone concentrations were measured. No effects of desipramine were seen in the pituitary or liver after 14 days' treatment, or in various areas of the central nervous system 24 h after administration. In view of the psychotropic properties of thyroid hormones, it seems possible that the observed increases in triiodothyronine concentrations, particularly in cortical areas, are involved in the mechanisms of action of desipramine.

Selenium deficiency alters thyroid hormone metabolism in guinea pigs

In guinea pigs, activity of glutathione peroxidase in most organs is markedly lower than in organs of other rodents despite comparable dietary intakes and tissue levels of selenium. To determine if metabolism of selenium with respect to other selenoproteins also differs in guinea pigs, we measured the effects of selenium intake on thyroid hormone metabolism. Weanling male Hartley Albino guinea pigs were fed a selenium-deficient Torula yeast-based diet, or the same diet supplemented with 0.5 mg selenium/kg diet as sodium selenate for 72 d. Growth was impaired in guinea pigs fed the unsupplemented diet. Activity of glutathione peroxidase was higher in tissues and plasma of supplemented guinea pigs than in selenium-deficient animals. However, it was still far lower than reported values for other rodent species. In selenium deficiency, activity of type 1 5'-iodothyronine deiodinase was 60% less in liver and 45% less in kidney. Concentration of thyroxine was 68% lower in kidney of selenium-deficient animals, and levels of 3,3',5-triiodothyronine in kidney and plasma were 44 and 31% lower, respectively. Thus, with the exception of thyroxine concentrations, thyroid hormone metabolism responds to selenium deficiency in guinea pigs as it does in rats, although the magnitude of that response is not as great.

Effects of thyroid hormone deiodination on regulation of thyroid axis in undernourished rats

The possible influence of hypothalamic and pituitary 5'-deiodinase II (5'-D-II) activity and 3,5,3'-triiodothyronine (T3) content on the modulation of thyroid-stimulating hormone (TSH) synthesis was studied. 1) Alterations in 5'-D-II activity and hypothalamic and pituitary T3 content produced by undernutrition were observed in fetal (21 days) and neonatal rats vs. controls. 2) After thyroidectomy, plasma TSH increased in both populations, undernourished and control, but pituitary TSH increased only in the former and not in the latter. The results obtained by giving small doses of thyroxine (T4; 0.5 micrograms/100 g body wt) to intact and thyroidectomized rats suggest a lower inhibitory effect by T4 on the pituitary in undernourished than in control rats. Although hypothalamic and pituitary 5'-D-II activity increased in both groups after thyroidectomy, the percentage increase was lower in undernourished vs. control rats, resulting in lower overall T3 content in tissues from undernourished animals. These studies on thyroid axis regulation show the in vivo regulation of TSH synthesis by hypothalamic and pituitary 5'-D-II activity and T3 content.

Identification of iodinated proteins in cultured thyrocytes and their possible significance for thyroid hormone formation

The thyroid gland is known to generate the iodinated hormones T3 and T4 from the prohormone thyroglobulin. In this report we examined whether polypeptides other than thyroglobulin are iodinated and hormonogenic in thyrocytes and the prerequisites for their iodination. In primary cultures of porcine thyrocytes, a substantial portion of organified radioiodine was incorporated into cellular proteins other than thyroglobulin. Some of these were identified by immunoprecipitation. They included proteins of the extracellular matrix, plasma membrane proteins, and lysosomal enzymes, which follow in part a secretion and recapture pathway. All of these proteins come into contact with the iodinating system of thyrocytes located on the apical plasma membrane and possess iodination consensus sequences. Immunoprecipitation with T3- or T4-specific antibodies showed that thyroid hormones were detectable only within thyroglobulin. This was confirmed by an analysis of the iodoamino acids of thyroglobulin, cathepsin-D (representing a secretory protein), and aminopeptidase-N (a membrane-integrated protein) by two-dimensional TLC, which revealed the presence of T3 and T4 only within the polypeptide chain of thyroglobulin. These results indicate that iodoproteins other than thyroglobulin do not participate in the generation of thyroid hormones in situ.

Donor thyroid function does not affect outcome in orthotopic liver transplantation

Brainstem death is associated with endocrine and metabolic alterations that can result in donor hemodynamic instability. It has been suggested that these changes can be reversed through hormonal manipulation of the donor. We measured thyroid hormone levels (free triiodothyronine [fT3], free tetraiodothyronine [fT4], reverse triiodothyronine) and thyroid-stimulating hormone (TSH) in 50 consecutive adult brain dead multiorgan donors. Recipient graft function was assessed using peak and day 5 aspartate aminotransferase, peak serum bilirubin, and minimum prothrombin time during the first week after OLT. Free T3 was low in 32/50 donors and was associated with a low fT4 in 24 cases. TSH was normal in 35 donors and we found no correlation between TSH levels and fT3 or fT4. Reverse triiodothyronine was normal or high in 96% of donors. Patient and graft survival were 96% for both the low and high fT3 groups. These data suggest that euthyroid sick syndrome is the most likely cause for the endocrine and metabolic alterations seen in brainstem-dead donors. This does not appear to influence liver recipient or graft survival.