Standardized Map of Iodine Status in Europe

Background: Knowledge about the population's iodine status is important, because it allows adjustment of iodine supply and prevention of iodine deficiency. The validity and comparability of iodine-related population studies can be improved by standardization, which was one of the goals of the EUthyroid project. The aim of this study was to establish the first standardized map of iodine status in Europe by using standardized urinary iodine concentration (UIC) data. Materials and Methods: We established a gold-standard laboratory in Helsinki measuring UIC by inductively coupled plasma mass spectrometry. A total of 40 studies from 23 European countries provided 75 urine samples covering the whole range of concentrations. Conversion formulas for UIC derived from the gold-standard values were established by linear regression models and were used to postharmonize the studies by standardizing the UIC data of the individual studies. Results: In comparison with the EUthyroid gold-standard, mean UIC measurements were higher in 11 laboratories and lower in 10 laboratories. The mean differences ranged from -36.6% to 49.5%. Of the 40 postharmonized studies providing data for the standardization, 16 were conducted in schoolchildren, 13 in adults, and 11 in pregnant women. Median standardized UIC was <100 μg/L in 1 out of 16 (6.3%) studies in schoolchildren, while in adults 7 out of 13 (53.8%) studies had a median standardized UIC <100 μg/L. Seven out of 11 (63.6%) studies in pregnant women revealed a median UIC <150 μg/L. Conclusions: We demonstrate that iodine deficiency is still present in Europe, using standardized data from a large number of studies. Adults and pregnant women, particularly, are at risk for iodine deficiency, which calls for action. For instance, a more uniform European legislation on iodine fortification is warranted to ensure that noniodized salt is replaced by iodized salt more often. In addition, further efforts should be put on harmonizing iodine-related studies and iodine measurements to improve the validity and comparability of results.

The significance of plasma adrenomedullin and calcitonin gene-related peptide concentration in patients with Type 2 diabetes mellitus who are treated for cardiovascular risk factors

OBJECTIVES

To evaluate the significance of plasma adrenomedullin and calcitonin gene-related peptide (CGRP) concentration in patients with Type 2 diabetes mellitus who are treated for hypertension and dyslipidemia.

METHOD

Plasma adrenomedullin and CGRP concentration, transthoracal echocardiography and ABPM were evaluated in 82 patients with Type 2 diabetes mellitus and 41 control subjects with no previous cardiovascular disease. All the subjects had casual blood pressure ≤140/90 mmHg or received antihypertensive medication, were treated by statin if LDL cholesterol was≥3mmol/L, by fibrates if triacylglyceroles≥2 mmol/L.

RESULTS

The mean age was 61±6 in patients with diabetes mellitus and 61±5 years in control subjects (p=0.9). Plasma CGRP was 3.0±1.8 in patients with diabetes mellitus and 2.3±1.0 ng/ml in control subjects (p=0.09). Plasma adrenomedullin was 2.2±0.9 in patients with diabetes mellitus and 2.8±1.1 ng/ml in control subjects (p=0.01). In patients with diabetes mellitus mass index of the left ventricle was significantly higher and the parameters of diastolic function were more deteriorated. Plasma adrenomedullin and CGRP correlated significantly negatively with serum creatinine and positively with mean 24 hours arterial blood pressure in patients with diabetes mellitus but not in control subjects. Plasma adrenomedullin concentration in patients with diabetes mellitus treated for hypertension was significantly reduced.

CONCLUSION

Despite concentration plasma adrenomedullin and CGRP modulation by cardioprotective treatment both neuropeptides remained involved in regulation of hemodynamic and metabolic parameters in patients with Type 2 diabetes mellitus. The low plasma of adrenomedullin in patients with Type 2 diabetic may be marker of the efficient intervention on cardiovascular risk factors.

Plasma adrenomedullin and subclinical cardiorenal syndrome in patients with type 2 diabetes mellitus

OBJECTIVE

To evaluate whether plasma adrenomedullin is involved in the previously reported significant inverse correlation between left ventricular (LV) end-diastolic pressure (peak velocity of early transmitral flow/peak velocity of early diastolic mitral annular motion ratio [E/E' ]) and estimated glomerular filtration rate (eGFR) in patients with type 2 diabetes mellitus, mild-to-moderate renal function impairment and LV relaxation impairment (E'≤7.1 cm/s).

METHODS

Plasma adrenomedullin concentration, E/E' and eGFR were assessed in 82 patients with type 2 diabetes.

RESULTS

Plasma adrenomedullin concentration was positively correlated with eGFR in patients with or without LV relaxation impairment, and inversely correlated with E/E' in patients with LV relaxation impairment. Multivariate linear regression analysis supported a role for plasma adrenomedullin in the association between E/E' and eGFR.

CONCLUSION

These results support the hypothesis that adrenomedullin modulates the interaction between the heart and kidneys in early subclinical cardiorenal syndrome in patients with type 2 diabetes mellitus.

RET mutation Tyr791Phe: the genetic cause of different diseases derived from neural crest

Activating germline RET mutations are presented in patients with familial medullary thyroid carcinoma (FMTC) and multiple endocrine neoplasia (MEN) types 2A and 2B, whereas inactivating germline mutations in patients with Hirschsprung's disease (HSCR). The aim of this study was to evaluate genotype-phenotype correlations of the frequently discussed Tyr791Phe mutation in exon 13 of the RET proto-oncogene. Screening of three groups of patients was performed (276 families with medullary thyroid carcinoma (MTC), 122 families with HSCR, and 29 patients with pheochromocytoma). We found this mutation in 3 families with apparently sporadic MTC, 3 families with FMTC/MEN2, 1 patient with pheochromocytoma, and 3 families with HSCR. All gene mutation carriers have a silent polymorphism Leu769Leu in exon 13. In three families second germline mutations were detected: Cys620Phe (exon 10) in MEN2A family, Met918Thr (exon 16) in MEN2B family, and Ser649Leu (exon 11) in HSCR patient. Detection of the Tyr791Phe mutation in MEN2/MTC and also in HSCR families leads to the question whether this mutation has a dual character (gain-of-function as well as loss-of-function). A rare case of malignant pheochromocytoma in a patient with the Tyr791Phe mutation is presented. This study shows various clinical characteristics of the frequently discussed Tyr791Phe mutation.

Vitamin D and its metabolites--supply of patients with various endocrine disorders and comparison of analytical methods

OBJECTIVE

Vitamin D is important not only for its effect on the homeostasis of calcium, but also for its anti-proliferative, pro-differentiation, pro-apoptotic and immuno-modulating effects in the tissues of living organisms. This work describes the results of serum 25(OH)D (n=2175) and 1alpha,25(OH)2D (n=2271) radioimmunoassays (RIA) conducted at the Institute of Endocrinology in Prague (Czech Republic) during the period of 2004-2006.

METHODS

Serum concentrations of vitamin D metabolites were determined by RIA kits from IDS Ltd., Boldon, UK. In a group of 20 healthy volunteers, results obtained using the RIA kit were compared with those obtained after serum extraction with acetonitrile, subsequent chromatographic (RP HPLC) separation of 25(OH)D and its detection in collected fractions using the same RIA kit from IDS.

RESULTS

The mean concentrations +/- S.D. in the samples studied were 76.4 +/- 45.6 nmol/l for 25(OH)D and 88.9 +/- 45.1 pmol/l for 1alpha,25(OH)2D. The mean concentrations of both metabolites were higher in women than in men, but only the difference for 1alpha,25(OH)2D) was statistically significant (p=0.0000). The lowest concentrations of 25(OH)D or 1alpha,25(OH)2D were found in patients with hyperparathyroidism, the highest concentrations those treated with cholecalciferol for osteoporosis and vitamin D deficiency. The relationship between 25(OH)D and 1alpha,25(OH)2D was expressed by the equation 1alpha,25(OH)2D = 71.0845 + 0.1890 * 25(OH)D (n=1065, p=0.0000, R2=0.0343). Based on the RIA results, only 4 % of individuals were inadequately supplied with 25(OH)D, 79 % were supplied adequately and almost 17 % were supplied more than adequately. Similarly, 1alpha,25(OH)2D shows inadequate concentration in 15 % of the individuals tested, 59 % of these individuals were within the reference range and 26 % had values exceeding the upper limit of the reference range. The mean concentrations of 25(OH)D obtained by HPLC separation were in average by 8 % higher than those obtained using only the RIA kit.

CONCLUSION

Interpretation of studies dealing with vitamin D stores must be based on precise and correct analytical procedures. However, only a few information exists about the influence of other vitamin D metabolites and conjugates on the concentration of immunoanalytically measured serum 25(OH)D or 1alpha,25(OH)2D.

The elimination of iodine deficiency in the Czech Republic: the steps toward success

The Czech Republic has a long history of iodine deficiency. Salt iodization was introduced in 1947, followed by a progressive correction of iodine deficiency. The present study reports the changes in the status of iodine nutrition and of thyroid function in the country from 1994 to 2002. The study included 29612 individuals, aged 0 to 98 years, including 5263 individuals randomly selected from the general population and 24349 individuals who attended the Institute of Endocrinology of Prague (hospital population). Urinary iodine was determined in all individuals. Measurements of serum thyrotropin (TSH), free thyroxine (FT4), free triiodothyronine (FT3), and thyroglobulin (Tg), were taken in 8544 to 19060 individuals. The iodine content of table salt was measured in 1130 samples. The median urinary iodine in the general and hospital populations were not significantly different. They progressively increased with time, starting from values indicating mild iodine deficiency (88-95 microg/L) prior to 1997, reaching the critical threshold of 100 microg/L in 1998, and optimal values between 120-140 microg/L since 2000. There was only a low and not significant positive correlation between the iodine content of salt and the urinary iodine. In contrast, urinary iodine showed marked seasonal changes, with the highest values during winter, when livestock were supplemented by mineral tablets containing iodine. Variables exploring thyroid function were all situated within the normal range in adults but another study (results not reported) has shown the persistence of slightly elevated TSH in neonates. The correction of iodine deficiency was not accompanied by unfavorable side effects. In conclusion, the Czech Republic has achieved sustainable elimination of iodine deficiency. Salt iodization has been a determining, but not the only, factor responsible for the success. Iodine supplementation of livestock and increased consumption of milk rich in iodine have probably played a determining role. Neonatal thyroid screening could constitute the major monitoring tool in order to insure sustainable elimination of iodine deficiency in the Czech Republic.

The thyrotrophin-releasing hormone (TRH)-like peptides in rat prostate are not formed by expression of the TRH gene but are suppressed by thyroid hormone

Thyrotrophin-releasing hormone (TRH)-immunoreactive peptides were extracted from rat prostate and divided into two groups by mini-column cation exchange chromatography. The amounts of the peptides in each group were determined by radioimmunoassay with a TRH antiserum. The unretained peptides which lacked a basic group and the retained peptides which possessed a basic group were further purified by high-performance liquid chromatography. The unretained fraction was found to contain a series of TRH-immunoreactive peptides, one of which corresponded chromatographically to synthetic pGlu-Glu-Pro amide and another to pGlu-Phe-Pro amide. None of the TRH-immunoreactive peptides in either fraction exhibited the chromatographic behaviour of TRH. Additional evidence for the absence of TRH gene expression in the prostate was obtained by Northern blot analysis and by application of polymerase chain reaction amplification, which failed to reveal TRH mRNA. Furthermore the preproTRH-derived peptide, preproTRH(53-74), could not be detected by radioimmunoassay. The influence of thyroid status was investigated on the levels of the TRH-like peptides in the prostate. Adult rats were treated chronically with thyroxine (T4) or propylthiouracil (PTU) and the concentrations of the TRH-immunoreactive peptides were determined by chromatography and radioimmunoassay. Treatment with T4 caused the levels of the neutral and acidic TRH-like peptides to fall to approximately one-third of the levels in the controls. No significant difference from the controls was seen in the concentrations of the peptides in the prostates of rats rendered hypothyroid by administration of PTU. The results demonstrate that rat prostate contains TRH-immunoreactive peptides which are not derived from the TRH gene.(ABSTRACT TRUNCATED AT 250 WORDS)