Brain glucose metabolism in hypothyroidism: a positron emission tomography study before and after thyroid hormone replacement therapy.

CONTEXT: Hypothyroidism is frequently associated with subtle behavioral and psychiatric symptoms. The consequences of inadequate thyroid hormone availability to brain metabolism are poorly understood. OBJECTIVE: This study assessed the relationships between neuropsychiatric symptoms and changes in relative regional cerebral glucose metabolism in hypothyroid patients undergoing thyroid hormone replacement therapy. DESIGN, SETTING, AND OUTCOME MEASURE: Relative regional cerebral glucose metabolism was compared in 13 previously untreated hypothyroid patients and 10 healthy control participants. Effects of thyroid hormone replacement therapy (levothyroxine, 3 months) were assessed using neuropsychiatric measures and positron emission tomography with [(18)F]fluorodeoxyglucose. RESULTS: Before treatment, hypothyroid patients exhibited lower regional activity than control subjects in the bilateral amygdala, hippocampus, and perigenual anterior cingulate cortex (ACC), left subgenual ACC, and right posterior cingulate cortex. Severity of depressive symptoms covaried negatively with pretreatment activity in the bilateral middle frontal gyrus and right subgenual and dorsal ACC. Thyroid hormone replacement therapy abolished pretreatment group differences in regional activity, robustly increased activity in the ventral ACC, and significantly reduced both clinician-rated and self-rated behavioral and psychiatric symptoms. Increased activity within the ventral ACC was associated with reduced somatic complaints, whereas increased activity within the dorsal ACC was associated with reduced depressive symptoms. CONCLUSIONS: Reduction of the behavioral complaints during thyroid hormone therapy is associated with a restoration of metabolic activity in brain areas that are integral to the regulation of affect and cognition. The findings suggest that thyroid hormone modulates regional glucose metabolism and psychiatric symptoms in the mature brain.

Troglitazone inhibits growth of MCF-7 breast carcinoma cells by targeting G1 cell cycle regulators.

Peroxisome proliferator activated receptor gamma (PPARgamma) is a member of the nuclear receptor superfamily. Ligand activation of PPARgamma has been shown to cause growth arrest in several human tumor cell types, but the underlying molecular mechanism has not been elucidated. We report here that the PPARgamma ligand troglitazone (TRO) inhibited MCF-7 cell proliferation by blocking events critical for G1 --> S progression. Flow cytometry demonstrated that TRO at 20 microM increased the percentage of cells in G1 from 51 to 69% after 24 h. Accumulation of cells in G1 was accompanied by an attenuation of Rb protein phosphorylation associated with decreased CDK4 and CDK2 activities. Inhibition of CDK activity by TRO correlates with decreased protein levels for several G1 regulators of Rb phosphorylation (cyclin D1, and CDKs 2, 4, and 6). Overexpression of cyclin D1 partially rescued MCF-7 cells from TRO-mediated G1 arrest. Targeting of G1 regulatory proteins, particularly cyclin D1, and the resulting induction of G1 arrest by TRO may provide a novel antiproliferative therapy for human breast cancer.

Long-term management and outcome of parathyroidectomy for sporadic primary multiple-gland disease.

HYPOTHESIS: For a specific subset of patients with sporadic primary multiple-gland parathyroid disease, subtotal parathyroidectomy results in long-term normocalcemia in the majority of patients, with a minimal complication rate. DESIGN: Retrospective analysis of outcomes in patients undergoing parathyroidectomy performed by a single surgeon (A.E.G.) between 1984 and 1999. SETTING: A multidisciplinary endocrine service based at a tertiary referral center. PATIENTS: Patients undergoing subtotal parathyroidectomy for primary hyperparathyroidism due to sporadic multiple-gland disease identified from a single surgeon's operative records (A.E.G.). MAIN OUTCOME MEASURES: Data analyzed included demographic factors, operative and pathologic findings, and postoperative and long-term clinical and laboratory results, including calcium and intact parathyroid hormone levels. RESULTS: Of 379 patients undergoing parathyroidectomy for hyperparathyroidism between 1984 and 1999, 49 (13%) had sporadic multiple-gland disease. Median preoperative calcium and intact parathyroid hormone (iPTH) levels were 2.7 mmol/L (10.8 mg/dL) and 11.79 pmol/L, respectively. Postoperative calcium and iPTH levels were available in 39 patients, and median values were 2.28 mmol/L (9.1 mg/dL) and 2.84 pmol/L, respectively. Long-term follow-up was available for 36 patients (73%), and duration ranged from 6 to 180 months (median, 44 months). Median calcium and iPTH levels at follow-up were 2.3 mmol/L (9.2 mg/dL) and 3.26 pmol/L, respectively, with 3 (8%) of 36 patients having evidence of persistent or recurrent hyperparathyroidism. No patient had biochemical evidence of hypoparathyroidism at long-term follow-up. Five patients (14%) had persistent elevated iPTH levels (range, 8.11-10.95 pmol/L) and normal calcium levels. CONCLUSIONS: Subtotal parathyroidectomy for sporadic primary multiple-gland disease resulted in a long-term normocalcemia rate of 92%, with minimal complications. Selective subtotal parathyroidectomy can yield excellent long-term results in patients with multiple-gland disease.

Apigenin inhibits growth and induces G2/M arrest by modulating cyclin-CDK regulators and ERK MAP kinase activation in breast carcinoma cells.

We have previously reported that apigenin inhibits the growth of thyroid cancer cells by attenuating epidermal growth factor receptor (EGF-R) tyrosine phosphorylation and phosphorylation of ERK mitogen-activated protein (MAP) kinase. In this study, we assessed the growth inhibitory effect of apigenin on MCF-7 breast carcinoma cells that express two key cell cycle regulators, wild-type p53 and the retinoblastoma tumor suppressor protein (Rb), and MDA-MB-468 breast carcinoma cells that are mutant for p53 and Rb negative. We found that apigenin potently inhibited growth of both MCF-7 and MDA-MB-468 breast carcinoma cells. The approximate IC50 values determined after 3 days incubation, were 7.8 micrograms/ml for MCF-7 cells, and 8.9 micrograms/ml for MDA-MB-468 cells, respectively. Because the cell cycle studies using FACS showed that both MCF-7 and MDA-MB-468 cells were arrested in G2/M phase after apigenin treatment, we studied the effects of apigenin on cell cycle regulatory molecules. We observed that G2/M arrest by apigenin involved a significant decrease in cyclin B1 and CDK1 protein levels, resulting in a marked inhibition of CDK1 kinase activity. Apigenin reduced the protein levels of CDK4, cyclins D1 and A, but did not affect cyclin E, CDK2 and CDK6 protein expression. In MCF-7 cells, apigenin markedly reduced Rb phosphorylation after 12 h. We also found that apigenin treatment resulted in a dose- and time-dependent inhibition of ERK MAP kinase phosphorylation and activation in MDA-MB-468 cells. These results suggest that apigenin is a promising antibreast cancer agent and its growth inhibitory effects are mediated by targeting different signal transduction pathways in MCF-7 and MDA-MB-468 breast carcinoma cells.

Thyrotoxicosis in a male patient associated with excess human chorionic gonadotropin production by germ cell tumor.

We report a case of a man with thyrotoxicosis due to excess production of human chorionic gonadotropin (hCG) by metastatic choriocarcinoma, followed by alterations of his thyroid function tests by nonthyroidal illness. All reported cases of thyrotoxicosis due to high hCG levels in male patients are reviewed. Patients with this syndrome usually have widespread choriocarcinoma and relatively few symptoms of thyrotoxicosis. Typically, if the patient survives the metastatic germ cell tumor, the thyrotoxicosis resolves as the hCG levels decrease after chemotherapy directed at the choriocarcinoma. Only rarely are specific antithyroid medications required. The hCG molecule directly stimulates the thyroid gland, and these patients appear to have in the serum a predominance of acidic variants of hCG with greater intrinsic thyroid-stimulating activity than the hCG secreted during a normal pregnancy. In general, these patients have a poor prognosis due to the usually widespread nature of the germ cell tumor at the time of diagnosis.

Amyloid goiter in a case of systemic amyloidosis secondary to ankylosing spondylitis.

Infiltrative diseases of the thyroid include systemic sclerosis, hemochromatosis, sarcoidosis, chondrocalcinosis and amyloidosis. Only rarely does thyroid amyloidosis result in clinically palpable goiter. Classically, amyloidosis is associated with tuberculosis, rheumatoid arthritis, multiple myeloma or inflammatory bowel disease. Only rarely does clinical amyloidosis develop in the setting of ankylosing spondylitis. We describe a case of amyloid goiter in a patient with ankylosing spondylitis-associated amyloidosis.

Unilateral adrenal medullary hyperplasia: another form of curable hypertension?

A case of unilateral adrenal medullary hyperplasia is presented in a 49-year-old caucasian female without multiple endocrine neoplasia association. The patient presented with episodic hypertension and paroxysms suggesting an underlying phaeochromocytoma. Biochemical supported this diagnosis but no discrete tumour was found on preoperative localising studies or at the time of surgery. The patient underwent a unilateral adrenalectomy with confirming adrenal medullary hyperplasia with complete resolution of her symptoms for six months.

Growth inhibitory effects of flavonoids in human thyroid cancer cell lines.

Previous studies have indicated that flavonoids exhibit antiproliferative properties on some hormone-dependent cancer cell lines, such as breast and prostate cancer. In the present study, the effects of some selected flavonoids, genistein, apigenin, luteolin, chrysin, kaempferol, and biochanin A on human thyroid carcinoma cell lines, UCLA NPA-87-1 (NPA) (papillary carcinoma), UCLA RO-82W-1 (WRO) (follicular carcinoma), and UCLA RO-81A-1 (ARO) (anaplastic carcinoma) have been examined. Among the flavonoids tested, apigenin and luteolin are the most potent inhibitors of these cell lines with IC50 (concentration at which cell proliferation was inhibited by 50%) values ranging from 21.7 microM to 32.1 microM. The cells were viable at these concentrations. Using NPA cells known to be estrogen receptor positive (ER+), it was shown that no significant [3H]-E2 displacement occurred with these flavonoids at the IC50 concentration. In WRO cells that are known to have an antiestrogen binding site (AEBS), biochanin A caused a stronger inhibitory growth effect (IC50 = 64.1 microM) than in NPA and ARO cells. In addition, it was observed that biochanin A has an appreciable binding affinity for the AEBS as indicated by the displacement of [3H]-tamoxifen from the WRO cells. In summary, flavonoids have potent antiproliferative activity in vitro against various human thyroid cancer cell lines. The inhibitory activity of certain flavonoid compounds may be mediated via the AEBS and/or type II EBS. The observation that ARO cells that lack both the AEBS and the ER are effectively inhibited by apigenin and luteolin suggest that other mechanisms of action are operative as well. The present study suggests that flavonoids may represent a new class of therapeutic agents in the management of thyroid cancer.

Signal pathways involved in apigenin inhibition of growth and induction of apoptosis of human anaplastic thyroid cancer cells (ARO).

Recently we demonstrated that several flavonoids can inhibit the proliferation of certain human thyroid cancer cell lines. Among the flavonoids tested, apigenin and luteolin are the most effective inhibitors of these tumor cell lines. In the present study, we investigated the signal transduction mechanism associated with the growth inhibitory effect of apigenin, using a human anaplastic thyroid carcinoma cell line, ARO (UCLA RO-81-A-1). Using Western blot method, it was shown that the inhibitory effect of apigenin on ARO cell proliferation is associated with an inhibition of both EGFR tyrosine autophosphorylation and phosphorylation of its downstream effector mitogen activated protein (MAP) kinase. Protein levels of these signaling molecules were not affected. The inhibitor of phosphorylation by apigenin occurred within 30 min and continued for 4 h. A dose-dependent inhibition was demonstrable ranging from 12.5 microM to 50 microM. The level of phosphorylated c-Myc, a nuclear substrate for MAPK, was depressed from 16-48 h after apigenin treatment, finally leading to a programmed cell death involving DNA fragmentation. Furthermore, treatment with apigenin resulted in the inhibition of both anchorage-dependent and anchorage-independent thyroid cancer cell growth. In summary, apigenin is a promising inhibitor of signal transduction pathways that regulate the growth (anchorage-dependent and independent) and survival of human anaplastic thyroid cancer cells. Apigenin may provide a new approach for the treatment of human anaplastic thyroid carcinoma for which no effective therapy is presently available.

Paper chromatography prior to cortisol RIA allows for accurate use of the dexamethasone suppression test in chronic renal failure.

The assessment of the hypothalamic-pituitary-adrenal axis in patients with chronic renal failure (CRF) on hemodialysis is often hampered by abnormal responses to the standard 1-mg dexamethasone suppression test. Various mechanisms have been proposed to explain this lack of suppressibility. The present study was designed to look into the mechanisms possible for these findings in patients with CRF. We studied 6 patients with CRF on hemodialysis and 5 healthy subjects utilizing the 1-mg dexamethasone suppression test as well as the 50-mg hydrocortisone suppression test. Samples were assayed for dexamethasone, adrenocorticotropic hormone, corticosterone, and cortisol by both direct radioimmunoassay (RIA) and RIA after paper chromatography. Utilizing the direct cortisol RIA, 4 of 6 patients with CRF exhibited blunted dexamethasone suppression, while all 6 patients showed normal suppressibility after dexamethasone when cortisol was measured after paper chromatography. In contrast, all controls showed normal suppressibility regardless of the cortisol assay procedure used. The hydrocortisone suppression test was unreliable in the setting of CRF. Mean dexamethasone levels were similar in both groups. Plasma adrenocorticotropic hormone levels were significantly higher in the CRF patients, possibly indicative of an underlying hypothalamic-pituitary-adrenal axis abnormality. Abnormalities in dexamethasone suppression testing in patients with CRF may be explained by the overestimation of cortisol levels by direct RIA rather than by alteration of dexamethasone absorption or metabolism. Measurement of cortisol after paper chromatography is superior to direct RIA of cortisol in patients with CRF.

Calcium-sensing by parathyroid glands in secondary hyperparathyroidism.

Calcium-sensing by the parathyroids is abnormal in familial benign hypocalciuric hypercalcemia and in primary hyperparathyroidism (primary HPT), but the role of a calcium-sensing defect in uremic secondary hyperparathyroidism (secondary HPT) remains controversial. To study the regulation of PTH release by calcium, set point estimates were obtained using the four parameter model during in vivo dynamic tests of parathyroid gland function in 31 patients with secondary HPT, 8 patients with advanced secondary HPT studied shortly before undergoing parathyroidectomy (Pre-PTX), 3 patients with primary HPT, and 20 subjects with normal renal function (NL); the response to 2-h i.v. calcium infusions was also evaluated. Neither blood ionized calcium (iCa+2) levels nor the set point for calcium-regulated PTH release differed between secondary HPT and NL; iCa+2 levels and set point values were moderately elevated in Pre-PTX and markedly elevated in primary HPT. Compared with values obtained in NL, the lowest serum PTH levels achieved during calcium infusions, expressed as a percentage of pre-infusion values, were incrementally greater in secondary HPT, Pre-PTX, and primary HPT, whereas the slope of the relationship between iCa+2 and PTH, expressed as the natural logarithm (ln) of percent preinfusion values, decreased incrementally in secondary HPT, Pre-PTX, and primary HPT. The inhibitory effect of calcium on PTH release is blunted both in secondary HPT and primary HPT because of increases in parathyroid gland mass, but a calcium-sensing defect is a late, rather than early, consequence of renal secondary HPT.

Sentinel lymphadenectomy in thyroid malignant neoplasms.

BACKGROUND: Lymph node metastases for well-differentiated thyroid cancer are associated with high recurrence rates. Surgical options consist of blind nodal sampling, "berry-picking" procedures, and modified radical neck dissections. Sentinel lymph node dissection (SLND) has been described by our institution for melanoma and breast cancer. We have investigated the feasibility of SLND for thyroid cancer. DESIGN: From August 1994 to October 1996 we investigated the technique of intraoperative lymphatic mapping and SLND in 17 patients undergoing surgical management of a suspicious thyroid nodule not accompanied by palpable cervical adenopathy. SETTING: Patients were referred from endocrinologists in community and academic practices. Procedures were performed in a community hospital. PATIENTS: There were 14 women and 3 men, ranging in age from 22 to 69 years (median, 48 years). INTERVENTIONS: At surgery, we exposed the thyroid lobe and used a tuberculin syringe to inject 0.1 to 0.8 mL of 1.0% isosulfan blue dye (mean, 0.5 mL) directly into the thyroid mass. Within seconds the blue dye passed along the lymphatics to the sentinel lymph node, which was then excised. Nodes were examined by routine processing and keratin immunohistochemical analysis to detect micrometastasis. MAIN OUTCOME MEASURES: The feasibility of lymphatic mapping in determining primary drainage of suspicious thyroid nodules. RESULTS: Lymphatic mapping and SLND was followed by total thyroidectomy, except in 1 patient who underwent lobectomy for benign disease. Of the 17 nodules, 12 were ultimately diagnosed as thyroid carcinoma, 3 were follicular adenomas, and 2 were colloid nodules. Tumor sizes ranged from 0.8 to 4.0 cm. Lymphatic mapping was unsuccessful in 2 patients, whose lymphatics mapped to the retrosternum. All of the sentinel lymph nodes were paratracheal except in 2 women who also had jugular nodes that stained blue. Five (42%) of the 12 tumor nodules were associated with positive sentinel lymph nodes. Central neck dissections were performed in 5 patients; in 2 instances (17%), the sentinel node was the only tumor-bearing lymph node. CONCLUSIONS: This is the first report of SLND for thyroid carcinoma. Our preliminary findings indicate that SLND can detect nonpalpable nodal metastasis with the same ease as in melanoma and breast cancer. The clinical significance of this technique in thyroid cancer remains to be determined.

Differences in PTH (1-84) release in response to ambient calcium concentrations of parathyroid adenoma fragments and dispersed parathyroid adenoma cells in culture.

In a previous study we observed that during perfusion of normal human parathyroid tissue, the release of PTH (1-84) was modulated by ambient extracellular calcium (Ca++) and lithium (Li+) concentrations in the media and preliminary studies indicated that this stimulus-response coupling was absent in human parathyroid adenoma fragments. The present study compares the responsiveness of parathyroid adenoma fragments and isolated parathyroid adenoma cells from the same adenoma and their response to Ca++ changes and Li+ presence in culture media. The data indicate that parathyroid adenoma tissue fragments fail to respond to ambient changes in Ca++ and Li+. In contrast, dispersed parathyroid cells preparations responded with a significant increase of PTH (1-84) release (50%) under the influence of low ambient calcium concentrations. Six of the dispersed cell preparations also responded with a 45% decrease in PTH release under the influence of a high Ca concentration in the medium. Isolated parathyroid cells obtained from the same adenoma's did not respond to the presence of Li++ in the medium. These data suggest tat human parathyroid adenoma tissue functions autonomously and is not sensitive to calcium regulation in the tissue configuration as opposed to the isolated cell suspensions. The nature of this difference remains elusive.

Human thyroglobulin reference material (CRM 457). 1st Part: Assessment of homogeneity, stability and immunoreactivity.

This paper describes the assessment of the homogeneity and stability of a purified and lyophilized human thyroglobulin (Tg), and characterizes its immunoreactivity. The purified and lyophilized Tg is intended to be used as a primary reference material to establish calibration of working serum based reference material. The programme involved the participation of 15 European laboratories and one laboratory from the United States. The homogeneity of the content of the ampoules was considered acceptable (< 9%). The stability was tested by accelerated temperature degradation showing predicted annual relative losses of 0.01% at -70 degrees C and 1.04% at -20 degrees C. The immunoreactivity of the Tg material as measured in different laboratories varied mostly according to the method used rather than the laboratory. The interlaboratory variability showed that the two commercial methods used in several laboratories (kit 1 and 2) had an interlaboratory variation (CV) of 15.9% (N = 5) and 7.1% (N = 3), respectively, whereas the total interlaboratory CV was 64.3% (N = 18). The immunoreactive Tg had dilution curves parallel with other Tg calibrators (those of the methods). Dilution curves of the Tg material after storage at various temperatures and time were parallel in both RIA and IRMA. In conclusion, we have prepared a Tg reference material which in extensive studies in several participating laboratories has demonstrated a sufficient homogeneity and stability as well as dilution curves parallel to the calibrators of all the immunoassays tested in the study. This reference material is considered the first step towards decreasing the interlaboratory variability between Tg immunoassays.

Human thyroglobulin reference material (CRM 457). 2nd Part: Physicochemical characterization and certification.

This report describes the characterization of a purified human thyroglobulin (Tg) reference material, and details the procedures used in its certification. The purified Tg is intended to be used as a primary reference material to establish calibration of working serum based reference material for immunoassay procedures. The programme involved the participation of 15 European laboratories and one laboratory from the United States. The physicochemical characterization showed by polyacrylamide gel electrophoresis and immunoblotting that the purified Tg had for the major part the expected molecular size of 660 kDa with traces of lower molecular forms. The amino acid composition was close to that demonstrated for the cDNA and the content of iodine was in keeping with a moderately to highly iodinated Tg. The mass concentration in reference material RM 457 is certified to be (0.324 +/- 0.018) g/L on the basis of protein determined by the Lowry method and supported by nitrogen determination, absorbance measurement, and amino acid analysis. This reference material is considered the first step towards decreasing the interlaboratory variability between Tg methods of measurement.

Use of sodium ipodate in management of hyperthyroidism in subacute thyroiditis.

Five hyperthyroid patients (two men and three women) with typical features of subacute thyroiditis were treated with sodium ipodate (Oragrafin; 0.5 g, orally daily or every other day) for 15-60 days; the treatment was stopped when both serum T4 and T3 levels were normal. All patients studied demonstrated a prompt normalization of serum T3, improvement in clinical symptoms of hyperthyroidism, and/or weight gain. We observed no side-effects of treatment with sodium ipodate. Our data suggest that sodium ipodate is a safe and effective agent for management of hyperthyroidism in subacute thyroiditis.

Presence of a specific antiestrogen binding site on human follicular thyroid carcinoma cell line (UCLA RO 82 W-1): inhibition by an endogenous ligand present in human serum.

A receptor for antiestrogens, distinct from the estrogen receptor, has been identified in several tissues including the MCF-7 breast cancer cell line. Estrogen receptors have also been found in normal and pathological thyroid tissue homogenates. We demonstrate the presence of an antiestrogen binding site (AEBS) on a pure human follicular thyroid carcinoma cell line (UCLA RO 82 W-1) using a 3H-tamoxifen (3H-TAM) binding assay. The binding of 3H-TAM to the AEBS was determined after preincubation (30 min) of the cells with excess 17 beta-estradiol (2 mumol/L). Specific and saturable binding of 3H-TAM to the cells was observed. Displacement of the tracer from its binding site was dose dependent. Scatchard analysis revealed a dissociation constant (Kd) of 73 nmol/L, indicating a binding site with moderate affinity and capacity (72 pmol/10(6) cells). Using this assay we were also able to demonstrate the presence of an endogenous ligand for the AEBS in ethanol extracts of human serum. Cell growth and 3H-thymidine incorporation by the follicular thyroid carcinoma cells were inhibited when the cells were exposed to TAM (1.5 mumol/L). In conclusion, TAM is able to bind to a specific receptor on this follicular thyroid carcinoma cell line, and a natural circulating ligand present in ethanol extracts of human serum interferes with its binding.

Enterohepatic regulation and metabolism of 3,5,3'-triiodothyronine in hypothyroid rats.

Several steady state indices of thyroid hormone distribution, metabolism, excretion, and absorption were measured in intact hypothyroid and euthyroid rats, to explore the role of intestines and enterohepatic pathways in the dynamic regulation of whole-body thyroid hormone in these two states. Ten rats were studied, 5 normal control (N) and 5 rendered hypothyroid (3.48 vs. 19.8 ng/ml TSH) by surgical thyroidectomy 3.5 weeks earlier (HYPO). High specific activity 125I-labeled T3 (T3*) was infused at the same constant rate for 7 days from osmotic minipumps implanted sc. Daily urine and feces, and seventh-day cardiac and portal venous blood, bile, and whole intestinal contents were assessed. Bowel and feces were homogenized, extracted, and chromatographed, along with serum, bile, and urine samples. Bile, bowel, and fecal extract samples were also hydrolyzed with aryl-sulfatase and/or beta-glucuronidase and chromatographed to identify conjugates and determine total T3* in all fluid and tissue samples. In the N group, the bowel contained 21.2 +/- 1.22 (SD) times more T3* (mass) than plasma (199 ng vs. 9.39 ng), this ratio falling to 9.03 +/- 1.78 in the HYPO group (30.4 ng vs. 3.37 ng), a shift to relatively more T3* in blood. Urinary T3* was zero in both groups. But fecal excretion was 34 +/- 4.43% of total T3* infused (production) in N and only 20.3 +/- 3.05% in HYPO rats, closely paralleling reduced fecal bulk flow, and thus providing more time for T3* absorption. Endogenous T3 and T4 concentrations measured in portal plasma were 15-31% greater in normals and 69-95% greater in HYPO rats than in corresponding systemic plasma samples, a direct indication of absorption of endogenous T3 and T4 in both groups, with greater absorption in the HYPO group. About 66% total T3* was metabolically degraded in N rats, rising to approximately 80% in HYPO rats. Plasma clearance rates of T3 fell more than 50% in HYPO rats, and total T3 production fell to about 20% of normal. It appears that HYPO rats compensate for low T3 by fecally excreting a much smaller fraction of total T3 production, absorbing more T3 and T4, and leaving a larger fraction for T3 action and degradative metabolism.

Chronic lymphocytic leukemia presenting as a pituitary mass lesion.

We describe a unique case of chronic lymphocytic leukemia (CLL) in a patient who presented with bitemporal hemianopsia, adrenal insufficiency, and gonadotrophin deficiency. Studies revealed an enhancing intrasellar mass with suprasellar extension and displacement of the optic chiasm. Peripheral blood and cerebrospinal fluid (CSF) studies disclosed a monoclonal IgM kappa expressing B-cell CLL. Biopsy of the pituitary mass revealed dense infiltration of the pituitary gland by leukemic cells. This is, to our knowledge, the first reported case of CLL presenting as a pituitary mass lesion.