Glucose compensation, serum lipids and thyroid hormones (rT3 and rT3/T3 ratio in non-insulin-dependent (type 2) diabetics: 2

In 45 type 2 diabetics it was unable to be found a relation between the plasma lipids and the fasting blood glucose (G), HbA1c, reverse T3 (rT3), rT3/T3 ratio, and relative body weight (R.B.W.). The conclusion was reached that the alteration of the lipoprotein metabolism and the thyroid hormones in type 2 diabetics could be primitive and independent from the availability of the insulin.     

rT3 production in normal man, assessed from variations in serum rT3 during short-term rT3 infusion.

The metabolic clearance rate (MCR) of 3,3'5'-triiodothyronine (reverse T3, rT3) was estimated in normal human subjects by a modified noncompartmental method using the integrated increase in serum rT3 following intravenous infusion of 0.10 nmol/min rT3 for 4 hr. The MCR-rT3 was calculated to be 102.8 +/- 17.01/day and the daily rT3 disposal to be 33.0 +/- 9.5 nmol (mean +/- SD, n = 6). The MCR-rT3 compares well to that of previous studies employing tracer kinetic methods. The disposal rate of rT3 estimated in the present study is considerably lower than found in some previous studies. The discrepancy is due to differences in the measured levels of serum rT3 in normal subjects.     

Serum T3 level in the patients with hyperthyroidism after therapy.

Serum T3 level in various thyroid diseases was determined in unextracted serum with the Dainabot kit for T3 RIA. The serum T3 level in 33 normal subjects was 0.8-1.6 ng/ml. It was 5.7 +/- 3.5 ng/ml (mean +/- S.D.) in 36 hyperthyroid patients, and undetectable to 0.8 ng/ml in 21 hypothyroid patients. Generally the serum T4 and serum T3 decreased in parallel after radioiodine therapy for hyperthyroidism. However, in some cases the serum T3 level remained high in spite of normalized serum T4 after radioiodine therapy. This state indicated "T3-toxicosis", and hyperthyroidism was apt to recur. When thyroid function was observed for 2 years following radioiodine treatment, the ratio of serum T3 (T3 level before treatment/T3 level after treatment) decreased more significantly as compared with the ratio of serum T4 in euthyroid cases. Serum T3 provides a more sensitive index of thyroid function than serum T4 in euthyroid states after radioiodine or anti-thyroid drug therapy. The present data indicate that the serum T3 level and the T4/T3 ratio are valuable aids in the estimation of prognosis of hyperthyroid patients after various treatments.     

An elevation of BUN/creatinine ratio in patients with hyperthyroidism

Blood urea nitrogen (BUN/creatinine ratio was abnormally high (24.8 +/- 0.6) in untreated hyperthyroid patients due to both increase in BUN and decrease in creatinine concentration. BUN, creatinine and BUN/creatinine ratio were all completely normalized after restoration of euthyroid status. On the other hand, BUN/creatinine ratio was slightly suppressed in hypothyroidism before treatment and it was reversed by thyroxine treatment (12.6 +/- 4.0 and 16.3 +/- 3.3, before and after treatment, respectively). An age-related increase in BUN/creatinine ratio, which was primarily due to an age-related increase in BUN, was also found in hyperthyroid subjects (21.9 +/- 2.8 vs 27.7 +/- 9.0; first vs fifth decade) and in normal controls (13.7 +/- 2.8 vs 16.0 +/- 2.9; first vs fifth decade). To elucidate reasons for abnormal increase in BUN/creatinine ratio in hyperthyroidism, measurement of cardiac output and kinetic analysis on urea nitrogen (UN) and creatinine were performed. The results indicated a marked increase in cardiac output. Serum creatine concentration was clearly increased in hyperthyroid patients. Thus, serum creatinine concentration was suppressed due to a decrease in creatinine synthesis and an increase in renal creatinine excretion. BUN was high, primarily due to an increase in UN production secondary to excessive protein catabolism together with insufficient excretion of UN.     

Reduced serum acylated ghrelin levels in patients with hyperthyroidism

BACKGROUND AND OBJECTIVE: Recent studies have revealed that circulating ghrelin levels seem to play a role in energy homeostasis. The effect of hyperthyroidism on ghrelin levels is not fully known. METHODS: Serum levels of ghrelin and its relationship with insulin resistance were evaluated in 48 patients with hyperthyroidism and 43 euthyroid healthy controls. Thyroid hormones, insulin, glucose, ghrelin levels and lipid parameters were measured in all subjects. Insulin sensitivity was determined using the homeostasis model assessment. RESULTS: Serum ghrelin levels were significantly decreased in hyperthyroid patients than in controls (32.5 +/- 23.3 vs. 54.1 +/- 35.5 pg/ml, p < 0.001). Circulating ghrelin levels significantly correlated with age (r = -0.26, p = 0.01), fasting glucose (r = -0.21, p = 0.01), free triiodothyronine (r = -0.18, p = 0.04), free thyroxine (r = -0.23, p = 0.02) and thyroid stimulating hormone (r = 0.21, p = 0.04), but not with blood pressure, body mass index, lipid parameters, insulin and homeostasis model assessment (p > 0.05). Multiple regression analysis revealed glucose level to be the most important predictor of circulating ghrelin level. CONCLUSION: These results indicate that hyperthyroidism has effect on serum ghrelin levels. Further studies are needed for the exact mechanism.     

Decreased serum osteocalcin levels in patients with liver cirrhosis

Serum levels of osteocalcin (OC) have been found to be a specific biochemical parameter of bone formation. We measured serum levels of osteocalcin, parathyroid hormone (PTH) and 25-hydroxyvitamin D (25(OH)D) in 49 patients with liver cirrhosis, who are known to have an increased prevalence of metabolic bone disease, and a matched control group (n = 35). Serum levels of OC were significantly decreased in the patients with liver cirrhosis when compared to control subjects (P < 0.001). Serum levels of 25(OH)D were decreased (P < 0.001), whereas no statistical difference was found between the serum levels of PTH in the patients with liver cirrhosis and those of the controls. In a subgroup of 23 patients with cirrhosis of the liver and 34 control subjects, the bone mineral content (BMC) of the non-dominant forearm was determined by single photon absorptiometry. BMC was significantly lower in the patient with liver cirrhosis than the control subjects (P < 0.04). Our data demonstrate vitamin D deficiency, decreased bone formation and a decreased BMC in patients with liver cirrhosis.     

Clinical evaluation of accuracy in determining serum free thyroxine and free triiodothyronine in patients with non-thyroidal illness: immunoglobulin effect on T3/TBG ratio and T4/TBG ratio

We examined the effect of endogenous immunoglobulins (G, A and M) and albumin on the measurement of thyroid hormones by different methods, including a new non-isotopic immunoassay of free thyroxine (FT4) and free triiodothyronine (FT3), in a large number of patients with non-thyroidal illness (NTI). Variations in serum protein concentrations can affect the results of radioimmunoassay of human thyroid hormones and thyroxine binding globulin (TBG). Our data revealed that in patients with non-thyroidal illness, when fluctuations in serum gamma-globulin occurred the T3/TBG and T4/TBG ratios altered. Consequently, when patients are suffering from non-thyroidal illness with changing gamma-globulin levels, clinical scientists should take care when they use T3/TBG and T4/TBG ratios as a substitute for FT3 or FT4 estimation. We found FT4 and FT3 (determined with Amerlex-M kits) T3 and the T3/TBG ratio were altered inversely due to the difference in the serum gamma-globulin levels. A recently developed enhanced luminescence enzyme immunoassay for FT3 and FT4 (Amerlite FT3 and FT4 kits) provides more reliable and accurate results, because of its resistance to interference, especially from albumin and gamma-globulin.     

Low serum reverse T3 levels in patients with primary hyperparathyroidism

Although patients with primary hyperparathyroidism (1 degree HPT) were euthyroid, we measured serum thyroid hormone levels in 16 patients with 1 degree HPT together with 17 patients with hypercalcemia due to malignant diseases (HCM). In patients with 1 degree HPT, serum levels of T3, T4 and T3U were within normal range, but serum rT3 (reverse T3) levels (205 +/- 37 pg/ml, mean +/- SD) were significantly decreased as compared with those in normal controls (276 +/- 44 pg/ml, P less than 0.01). A significant inverse correlation was observed between the serum levels of rT3 and parathyroid hormone (PTH) (r = 0.54, P less than 0.05). After parathyroidectomy, serum rT3 levels were significantly elevated (240 +/- 56 pg/ml) compared to preoperative levels (P less than 0.01). Low levels of serum rT3 seemed to be attributed to the high levels of serum PTH. On the other hand, serum levels of T3 and T4 were low and serum rT3 levels were high in patients with HCM. Low serum rT3 allows for the differentiation of patients with 1 degree HPT from those with HCM.     

Acetylation phenotype and serum levels of T3 and T4 in patients with hypertension treated with propranolol

The acetylation phenotype has been investigated in 76 patients with untreated hyperthyroidism. In 65 of these patients including 23 with fast and 42 with slow acetylation phenotype, the blood serum concentrations of thyroxine and triiodothyronine were determined before and after propranolol therapy involving propranolol administration of a dose of 160 mg per day for 6 days. The occurrence of the fast acetylation phenotype among the patients with hyperthyroidism was similar to that found in the healthy population. Propranolol therapy caused a significant decrease in the blood serum concentration of triiodothyronine only in the patients with the slow acetylation phenotype.     

Decreased levels of serum platelet-activating factor acetylhydrolase in patients with rheumatic diseases

PAF is a potent inflammatory compound known to stimulate the release of various cytokines involved in rheumatic diseases. Elevated blood PAF levels are reported in these patients. We report that serum PAF acetylhydrolase activity (AHA) levels are decreased in patients with rheumatoid arthritis or osteoarthritis as compared to healthy controls. Serum and synovial fluid AHA levels were correlated in these patients. The present study suggests the potential role of AHA in controling systemic and/or local PAF levels in patients with rheumatic diseases.     

Serum TSH, T4, T3, FT4, FT3, rT3, and TBG in youngsters with non-ketotic insulin-dependent diabetes mellitus

Several parameters of thyroid function were studied in 112 non-ketoacidotic youngsters with insulin-dependent diabetes mellitus (IDDM). Levels of thyroxine (T4), reverse triiodothyronine (rT3), thyroxine-binding globulin (TBG) and T3 were lower than in controls, whereas FT4, and FT3 were normal. T4 levels in IDDM patients were positively related to T3, rT3 and TBG, and inversely related to haemoglobin A1 (HbA1). However, only 4 patients showed biochemical hypothyroidism (T4 less than 5 micrograms/100 ml), whereas their FT4, FT3 and thyroid-stimulating hormone (TSH) levels were normal. Concurrent variations of T3 and rT3 levels were found in IDDM patients; thus, their T3/rT3 ratios were stable or higher than in controls, indicating that peripheral deiodination of T4 is preferentially oriented to production of rT3 only during ketoacidosis. Although changes in thyroid function may reflect the degree of metabolic control of diabetes in a large population, the clinical usefulness of serum thyroid hormone measurements in an individual case still appears to be limited.     

Electrophoretic and enzymatic analysis of glycosaminoglycans in the blood serum of patients with hyperthyroidism

An effect of hyperthyroidism on the composition and levels of glycosaminoglycans in the blood serum was studied. Glycosaminoglycans isolated from 1-ml blood samples were assayed with the following techniques: carbazole, electrophoretic and enzymatic. Separation and assay of particular GAG were made with bidirectional electrophoresis. Isomers of the remaining chondroitin sulphates were assayed enzymatically. Electrophoretograms of GAG in blood serum of healthy women have shown two fractions: low sulphate chondroitin sulphate and chondroitin-4-sulphate. The same fractions of GAG were found in blood serum of the female patients with hyperthyroidism. Mean concentration of GAG in the blood serum of hyperthyroid patients increased by 51%: low sulphate chondroitin sulphate and chondroitin-4-sulphate concentrations increased by 22% and 190% respectively. Chondroitin sulphates in the blood serum of both groups were degraded to unsaturated disaccharides not containing sulphur and unsaturated 4-sulphate disaccharides. Concentrations of unsaturated 4-sulphate and unsaturated sulphur-free disaccharides increased by 71% and 17% in hyperthyroidism. Observed changes in the blood serum GAG concentrations reflect changes in the connective tissue metabolism in hyperthyroidism.     

T mu and T gamma-lymphocyte counts and their ratio in patients with brucellosis

The levels of circulating T mu- and T gamma-lymphocytes in brucellosis patients have been studied in relation to the clinical form of the disease, the severity of the process and the allergic transformation of the body. A decrease in the content of lymphocytes, affecting mainly T mu-cells and less commonly T gamma-cells, as well as a change in their ratio has been revealed. The level of this decrease depended on the clinical form of brucellosis, the severity of the course of acute and subacute brucellosis, the phase of chronic brucellosis and the allergic transformation of the body. The disproportion of immunoregulating cells in brucellosis, revealed in this study, is supposed to be of pathogenetic importance.     

Decreased serum brain-derived neurotrophic factor in Chinese patients with Type 2 diabetes mellitus

Brain-derived neurotrophic factor （BDNF） is a member of neurotrophin family associated with the proliferation, differentiation, activity-dependent plasticity, and survival of neurons in the central nervous system [1]. BDNF influences glucose metabolism and insulin sensitivity. For example, BDNF decreases serum glucose, insulin, and HbAlc levels in diabetic rats, suggesting that the BDNF may improve insulin sensitivity. In addition, animal models showed that BDNF levels in the central nervous system are highly related to peripheral serum BDNF levels [2]. It was found that BDNF may ameliorate glucose metabolism and prevent pan- creatic exhaustion in obese diabetic mice [3].     

Thyroid cancer in patients with hyperthyroidism

Thyroid cancer can be associated with thyrotoxicosis caused by Graves' disease, toxic multinodular goiter, or autonomously functioning thyroid adenoma. The objective of this study was to summarize current evidence regarding the association of thyroid cancer and hyperthyroidism, particularly with respect to the type of hyperthyroidism found in some patients, and whether this affects the outcome of the patient. A PubMed search was performed up to August 2011. Articles were identified using combinations of the following keywords/phrases: thyroid cancer, papillary thyroid cancer, follicular thyroid cancer, medullary thyroid cancer, anaplastic thyroid cancer, hyperthyroidism, Graves' disease, auto-nomous adenoma, toxic thyroid nodule, and toxic multinodular goiter. Original research papers, case reports, and review articles were included. We concluded that the incidence, as well as the prognosis of thyroid cancer associated with hyperthyroidism is a matter of debate. It seems that Graves' disease is associated with larger, multifocal, and potentially more aggressive thyroid cancer than single hot nodules or multinodular toxic goiter. Patients with Graves' and thyroid nodules are at higher risk to develop thyroid cancer compared to patients with diffuse goiter. Every suspicious nodule associated with hyperthyroidism should be evaluated carefully.