The Vitamin D paradox: bone density testing in females aged 45 to 74 did not increase over a ten-year period despite a marked increase in testing for vitamin D.

AIM: To determine whether increased vitamin D testing resulted in improved osteoporosis detection in Australian females aged 45-74 yr. METHODS: Longitudinal analysis of bone densitometry, 25-hydroxyvitamin D (25(OH)D) and full blood count (FBC) testing between 2001 and 2011. The number and rate of tests per 100,000 individuals and benefit in dollars for bone densitometry, 25(OH)D and FBC from 2001-2011 for individuals aged 45-74 yr were obtained from Medicare Australia. RESULTS: There was a disproportionate increase in 25(OH)D testing compared to bone density testing from 2001 to 2011, whereby 25(OH)D testing increased from 26,666 to 1.65 million p.a. and bone density testing increased from 41,453 to 66,100 p.a. Bone densitometry increased approximately 1.2 fold, whereas 25(OH)D testing increased by 55.2, 41.2 and 34.3 fold in females aged 45-54, 55-64 and 65-74 yr, respectively. This represents an increase in annual benefits from approximately $2.5-$4.1 million for bone density testing and $0.7-$40.5 million for 25(OH)D testing over the period. CONCLUSIONS: This study demonstrates that improved detection of vitamin D deficiency is not being translated into better detection in at-risk women of the consequences of vitamin D deficiency on target organs such as bone. This failure to translate rising awareness and better detection of vitamin D deficiency into physiological outcomes is a massive missed opportunity for improved bone health and reduced fracture risk.We propose that clinical practice guidelines be introduced not only for the purpose of diagnosis and testing for vitamin D, but to include recommendations for bone health testing in at-risk individuals.

Relationship of Type 2 diabetes to the prevalence, incidence and progression of age-related hearing loss.

AIMS: Type 2 diabetes and associated microvascular abnormalities are postulated to affect hearing. Our study reports on the relationship between Type 2 diabetes and the prevalence, 5-year incidence and progression of hearing impairment in a representative, older, Australian population. METHODS: The Blue Mountains Hearing Study is a population-based survey of age-related hearing loss conducted in a defined suburban area, west of Sydney. Hearing loss was defined as the pure-tone average of frequencies 0.5, 1.0, 2.0 and 4.0 kHz > 25 decibels hearing level (dB HL) in the better ear (bilateral hearing loss). Type 2 diabetes was defined from reported physician-diagnosed diabetes or fasting blood glucose > or = 7.0 mmol/l. RESULTS: Age-related hearing loss was present in 50.0% of diabetic participants (n = 210) compared with 38.2% of non-diabetic participants (n = 1648), odds ratio (OR) 1.55 [95% confidence interval (CI) 1.11-2.17], after adjusting for multiple risk factors. A relationship of diabetes duration with hearing loss was also demonstrated. After 5 years, incident hearing loss occurred in 18.7% of participants with, and 18.0% of those without diabetes, adjusted OR 1.01 (CI 0.54-1.91). Progression of existing hearing loss (> 5 dB HL), however, was significantly greater in participants with newly diagnosed diabetes (69.6%) than in those without diabetes (47.8%) over this period, adjusted OR 2.71 (CI 1.07-6.86). CONCLUSIONS: Type 2 diabetes was associated with prevalent, but not incident hearing loss in this older population. Accelerated hearing loss progression over 5 years was more than doubled in persons newly diagnosed with diabetes. These data explore further reported links between Type 2 diabetes and age-related hearing loss.

Normal thiopurine methyltransferase phenotype testing in a Crohn disease patient with azathioprine induced myelosuppression.

Severe cytopenias in patients with autoimmune conditions treated with azathioprine are well-recognized. Thiopurine methyltransferase (TPMT) enzymatic activity is subject to individual and ethnic variability. Patients with low TPMT activity (poor metabolizers) are at high risk of developing severe and potentially fatal haematopoietic toxicity. Studies have shown that essentially all TPMT-deficient patients will develop haematopoietic toxicity on administration of conventional thiopurine dosages (6-mercaptopurine, azathioprine). Therefore, screening for TPMT polymorphisms in patients before prescribing thiopurine drugs has been proposed. However, despite normal in vitro enzymatic activity, cytopenia may still occur in vivo. This is the case report of an Asian patient with Crohn disease harbouring a rare TPMT mutation on DNA sequencing, who developed neutropenic sepsis and anaemia after a flare of Crohn disease. The report illustrates the importance of monitoring for cytopenia in the setting of active inflammatory disease despite prior normal phenotyping, the role of predictive pharmacogenetics and the limitations of TPMT phenotype assays that may result in misclassification of at-risk patients.

Effect of repaglinide addition to metformin monotherapy on glycemic control in patients with type 2 diabetes.

OBJECTIVE: To compare the effect of repaglinide in combination with metformin with monotherapy of each drug on glycemic control in patients with type 2 diabetes. RESEARCH DESIGN AND METHODS: A total of 83 patients with type 2 diabetes who had inadequate glycemic control (HbA1c > 7.1%) when receiving the antidiabetic agent metformin were enrolled in this multicenter, double-blind trial. Subjects were randomized to continue with their prestudy dose of metformin (n = 27), to continue with their prestudy dose of metformin with the addition of repaglinide (n = 27), or to receive repaglinide alone (n = 29). For patients receiving repaglinide, the optimal dose was determined during a 4- to 8-week titration and continued for a 3-month maintenance period. RESULTS: In subjects receiving combined therapy, HbA1c was reduced by 1.4 +/- 0.2%, from 8.3 to 6.9% (P = 0.0016) and fasting plasma glucose by 2.2 mmol/l (P = 0.0003). No significant changes were observed in subjects treated with either repaglinide or metformin monotherapy in HbA1c (0.4 and 0.3% decrease, respectively) or fasting plasma glucose (0.5 mmol/l increase and 0.3 mmol/l decrease respectively). Subjects receiving repaglinide either alone or in combination with metformin, had an increase in fasting levels of insulin between baseline and the end of the trial of 4.04 +/- 1.56 and 4.23 +/- 1.50 mU/l, respectively (P < 0.02). Gastrointestinal adverse events were common in the metformin group. An increase in body weight occurred in the repaglinide and combined therapy groups (2.4 +/- 0.5 and 3.0 +/- 0.5 kg, respectively; P < 0.05). CONCLUSIONS: Combined metformin and repaglinide therapy resulted in superior glycemic control compared with repaglinide or metformin monotherapy in patients with type 2 diabetes whose glycemia had not been well controlled on metformin alone. Repaglinide monotherapy was as effective as metformin monotherapy.

Somatostatin-14 and its analog octreotide exert a cytostatic effect on GH3 rat pituitary tumor cell proliferation via a transient G0/G1 cell cycle block.

Somatostatin (SRIF) and its analogs exert potent inhibitory effects on hormonal hypersecretion. In addition, they have been demonstrated to inhibit the proliferation of various cell lines as well as the growth of some endocrine tumors in vivo. To evaluate the action of SRIF and its analog octreotide on the proliferation and cell cycle kinetics of endocrine cells, we investigated their effect on GH3 rat pituitary tumor cells, a GH-producing cell line. Using flow cytometric DNA analysis with propidium iodide staining, we found that octreotide inhibits the proliferation of synchronized GH3 cells, achieving a maximal reduction, compared to controls, of 19.4 +/- 5.3% and 22.4 +/- 5.1% with 100 ng/ml and 1000 ng/ml octreotide, respectively (P < 0.05). This effect was demonstrated to be due to a block in progression from the G0/G1 phase to the S phase of the cell cycle. This was most evident after 24 h of exposure to 100 ng/ml octreotide, at which time there was a 7.1 +/- 1.4% increase in cells in G0/G1 (P < 0.01) and a 6.6 +/- 1.3% decrease in cells in S phase (P < 0.01). However, unless octreotide was replenished, this effect was transient and overcome by 36-48 h. No apoptosis was seen, and trypan blue studies confirmed that cell death by necrosis did not occur. A single exposure to native SRIF-14 had little effect, but a G0/G1 cell cycle block and inhibition of proliferation were seen if SRIF was regularly replenished. We conclude that SRIF and octreotide exert a cytostatic effect on GH3 cells by causing a partial G0/G1 cell cycle block. These findings suggest that the actions of SRIF and octreotide occur through signal transduction pathways that act predominantly on downstream regulators.

Detection of extended distribution of beta2-thyroid hormone receptor messenger ribonucleic acid (RNA) in adult rat brain using complementary RNA in situ hybridization histochemistry.

In situ hybridization histochemistry using a complementary RNA probe, directed at the entire length of the thyroid hormone receptor beta2 (TRbeta2)-specific region (-56 to 495 bp), was used to evaluate expression of TRbeta2 messenger RNA (mRNA) in coronal sections of adult rat brain. An extended distribution and intense expression of TRbeta2 mRNA was found in several regions of rat brain, including regions where TRbeta2 mRNA had not been previously identified using PCR or in situ hybridization histochemistry. These areas included hippocampus (dentate gyrus and C1, -2, and -3), cerebral cortex (predominantly layer 3), arcuate nucleus, median eminence, medial geniculate nucleus, tegmental bundle, medial and lateral lemniscus, Purkinje layer of the cerebellum, and several brain stem nuclei. In conclusion, we have developed a highly sensitive and specific method to demonstrate TRbeta2 mRNA expression in adult rat brain. The present findings are in agreement with immunoreactive TRbeta2 studies of rat brain and argue against the presence of an unidentified T3-binding protein to explain the previous discordant results of TRbeta2 mRNA and protein studies. In addition, the specificity of distribution of TR beta2 mRNA to certain brain nuclei, particularly those involved in hearing, implies a specific functional role of this receptor subtype and provides a physiological basis to understand the effects of hypothyroidism on brain development.

Methimazole inhibits FRTL5 thyroid cell proliferation by inducing S-phase arrest of the cell cycle.

Previous studies, using tritiated thymidine uptake assays, had indicated a nil or stimulatory effect of methimazole (MMI) on thyroid cell proliferation. Whilst examining cell cycle kinetics of FRTL5 thyrocytes, we observed an inhibitory effect of MMI on thyroid cell proliferation. To further examine this observation, FRTL5 cells whilst in log phase proliferation were exposed to media containing either 6H or MMI in 6H. Cell number and cell cycle kinetics were examined using flow cytometric DNA analysis every 24 hrs for 96 hrs. We found that MMI inhibited cell proliferation (as assessed by cell number) throughout the experimental period. Cell cycle analysis revealed a persistent arrest of cells in S phase. Concomitantly, there was a fall in the proportion of cells in both G0G1 and G2M phases, in keeping with cell cycle arrest in S phase. Taken in isolation, the finding of a high proportion of cells in S phase would suggest stimulation of cell proliferation, consistent with the findings of previous studies which used tritiated thymidine uptake assays to assess cell proliferation. However, the absence of a concomitant increase in total cell number renders this argument invalid and argues for a specific effect of MMI on the cell cycle. This study demonstrates a hitherto unrecognised inhibitory action of MMI on FRTL5 thyroid cell proliferation which has implications in understanding the broader effects of MMI on thyroid cell physiology. Additionally, this study highlights the dangers of using tritiated thymidine uptake measures as the sole indicator of mitogenic activity.

Evidence that the inhibitory effects of iodide on thyroid cell proliferation are due to arrest of the cell cycle at G0G1 and G2M phases.

The thyroid gland is unique in its ability to respond to ambient levels of iodine to autoregulate thyroid function and, possibly, thyroid cell proliferation. Although the inhibitory effects of iodide on thyroid cell proliferation have been previously reported, the exact mechanism and site of action of iodide on cellular proliferation events are poorly understood. Our initial experiments established the optimal cell plating density and timing to achieve exponential cell growth of FRTL5 thyroid cells, and subsequent studies using flow cytometric DNA analysis established the normal cell cycle kinetics of FRTL5 thyroid cell proliferation. FRTL5 cells were then exposed to graded concentrations of sodium iodide to establish whether the inhibitory effects of iodide are mediated through specific cell cycle events. We observed that increasing concentrations of iodide inhibited FRTL5 thyroid cell proliferation. Analysis of the cell cycle revealed two specific effects of iodide on cell cycle kinetics. The first was an arrest of cells in G0G1, evidenced by an accumulation of cells in this phase and a concomitant reduction in the percentage of cells in the S-phase. The second was an arrest of cells in the G2M phase of the cycle. G0G1 and G2M arrest occurred within 24 h and then reached a plateau. Iodide exposure did not increase the number of cells undergoing necrosis. The addition of methimazole at two concentrations (0.2 and 2 mM) to cells exposed to 100 mM NaI prevented the accumulation of cells in G2M, but did not abolish the accumulation of cells in G0G1 or the reduction in cell number. These results indicate that the inhibitory effects of iodide on FRTL5 thyroid cell proliferation are mediated by its action at two critical regulating points of the cell cycle, G0G1 and G2M. It appears that organified iodine may mediate the cell cycle arrest in the G2M phase, whereas inorganic iodide may be responsible for the inhibitory effects at G0G1.

Growth hormone does not increase thyroid size in the absence of thyrotropin: a study in adults with hypopituitarism.

Goiter is a frequent clinical finding in patients with acromegaly, an effect mediated by chronically elevated insulin-like growth factor I (IGF-I) levels. It is unclear, however, whether the presence of TSH is a prerequisite for the growth-promoting actions of IGF-I on the human thyroid. We, therefore, studied a group of subjects with hypopituitarism, who were deficient in both TSH and GH, examining the effects of GH replacement therapy on thyroid size and function. GH replacement was initiated in 14 subjects with hypopituitarism. After 6 months of recombinant human GH therapy at 0.25 IU/ kg week, IGF-I levels increased from 11.5 +/- 6.0 to 32.4 +/- 15.4 nmol/L (P = 0.002). Thyroid volume, as determined by ultrasound, did not change significantly over this period. Similarly, there was no change in thyroglobulin levels after treatment with GH, but there was a decrease in the free T4/free T3 ratio (P = 0.043). Pretreatment thyroid size in subjects with hypopituitarism was also compared to that in a group of age- and sex-matched controls. The size of thyroid glands in the hypopituitarism group was smaller than that in controls (P = 0.015). We found that GH therapy did not increase thyroid size in patients with hypopituitarism. From these data we conclude that in vivo, IGF-I does not independently stimulate thyroid growth, but promotes thyroid cell proliferation by potentiating the mitogenic action of TSH.

Growth hormone treatment increases cytochrome P450-mediated antipyrine clearance in man.

We used the antipyrine clearance test (APC) to examine the effect of growth hormone (GH) therapy on hepatic cytochrome P450 (CYP) enzyme activity. Eleven GH deficient adults were randomized to receive GH or placebo for 6 months, all subjects subsequently received GH. Before treatment, APC was below the normal range in six subjects. We found an increase in APC in the subjects randomized to receive GH compared to those on placebo (median change +0.14 ml/min/kg [range + 0.04 to + 0.20]vs -0.04 ml/min/kg [range -0.07 to + 0.04], p = 0.011). The stimulatory effect of GH on drug metabolism was confirmed by the data for 3 months GH treatment in all 11 subjects, with APC increasing from 0.33 ml/min/kg (range 0.22 to 0.69) to 0.50 ml/min/kg (range 0.27 to 0.83), p = 0.018). These data indicate that GH modulates hepatic CYP activity. This has important clinical implications, as the hepatic metabolism of drugs and hormones may be altered in patients undergoing GH therapy.

Supplementary iodine fails to reverse hypothyroidism in adolescents and adults with endemic cretinism.

The efficacy of supplemental iodine in correcting hypothyroidism in adults and older children with endemic myxedematous cretinism is not known. To investigate this issue we administered im iodized oil (1.5 mL) to 28 hypothyroid endemic cretins (TSH, greater than 5 mIU/L) from western China, aged 14-52 yr (mean = 29 SD = 11 yr). Clinical examination, intelligence testing (Hiskey Nebraska Test of Learning Aptitude and the Griffiths Mental Development Scales), and thyroid function tests were performed before and 6 months after iodine supplementation. We found that signs of thyroid hormone deficiency, dwarfism, and delayed sexual maturity persisted after iodine supplementation. Further, mental disability and other clinical features of neurological damage were not altered by treatment. The mean serum concentration of total T4 before treatment was 75 nmol/L (SD = 40) and fell after iodized oil administration to 56 nmol/L (SD = 29; P less than 0.001). Mean serum levels of TSH before and after iodine showed a paradoxical fall [85 mIU/L (SD = 102) and 46 mIU/L (SD = 46), respectively]. Serum TSH levels decreased into the normal range (less than 5 mIU/L) in only 1 of 28 patients (4%). We conclude that iodine supplementation does not reverse thyroid hormone deficiency or its sequelae in adolescents and adults with endemic myxedematous cretinism. Iodized oil in this age group of patients with endemic cretinism does not appear to be beneficial and should be used with caution.

A comparative study of neurological and myxedematous endemic cretinism in western China.

Endemic cretinism occurs in areas of severe iodine deficiency and is manifested by two major clinical patterns, myxedematous and neurological. The relationship between these types and the factors responsible for the clinical variability are not clear. We examined 69 endemic cretins, aged 4-52 yr, categorized clinically at the beginning of the study into the three traditional types of endemic cretins, myxedematous (n = 25), neurological (n = 15), and the mixed form (n = 29), from a previously unreported endemia in Qinghai Province, China. These patients underwent detailed endocrine and neurological examination, including intelligence assessment using the Hiskey-Nebraska Test of Learning Aptitude or the Griffiths Mental Development Scales, audiometry (in a subset of 37 patients); thyroid function testing and thyroid ultrasonography; and radiology of the skull, hand, and hip. We found that categorization of the cretins into the conventional types did not reflect the pathophysiology of the condition, since an identical pattern and intensity of neurological, intellectual, and audiometric deficits were common to and equally present in all three types of endemic cretins regardless of their thyroid function. Gait disorder (in 99%) and pyramidal signs such as patellar hyper-reflexia (in 91%) were the most common neurological abnormalities. There was no difference in mean intelligence test scores among the three groups [overall mean intelligence score (Hiskey or Griffiths tests), 28.8 +/- 12.8 (SD)]. The differing clinical manifestations of cretinism could be explained by the length and severity of thyroid hormone deficiency. Myxedematous cretins were severely thyroid hormone deficient, and as a result sexually immature, dwarfed, and had retarded skeletal maturity. They had clinical and sonographic thyroid atrophy, rather than goiter. Although neurological cretins were euthyroid, linear growth arrest lines (demonstrated radiologically) in the long bones of these cretins suggested previous hypothyroidism. Furthermore, all cretins were growth retarded when compared with peers of similar age and race. Our data therefore suggest that the different clinical types of endemic cretinism are in fact the same disorder phenotypically modified by the length and severity of postnatal hypothyroidism. The neurological manifestations are interpreted as reflecting the effects of maternal and fetal hypothyroxinemia, secondary to severe iodine deficiency, on the developing nervous system.

The Australian Multicenter Trial of Growth Hormone (GH) Treatment in GH-Deficient Adults.

GH treatment in adults with GH deficiency has numerous beneficial effects, but most studies have been small. We report the results of an Australian multicenter, randomized, double-blind, placebo-controlled trial of the effects of recombinant human GH treatment in adults with GH deficiency. GH deficiency was defined as a peak serum GH of < 5 mU/liter in response to insulin-induced hypoglycemia. Patients were randomly assigned to receive either GH (0.125 U/kg per week for 1 month and 0.25 U/kg per week for 5 months) or placebo. After 6 months, all patients received GH. The primary end points were biochemical responses, body composition, quality of life, and safety. One hundred sixty-six patients (72 females and 91 males) with a mean age of 40 +/- 1 yr (+/- SEM; range 17-67 yr) were recruited. Serum insulin-like growth factor-I (IGF-I) increased from a standard deviation score of -2.64 +/- 0.27 (range -8.8 +3.82; n = 78) to +1.08 +/- 2.87 (range -7.21 to +6.42) at 6 months in the GH/GH group; 38% of the whole group were above the age-specific reference range following treatment [17.6% and 68.9% with subnormal (< 2 SD) or normal (+/- 2 SD) pretreatment levels, respectively]. Fasting total cholesterol (P = 0.042) and low-density lipoprotein cholesterol (P = 0.006) decreased over the first 6 months. Fat-free mass increased in the first 6 months whether measured by bioelectrical impedance (P < 0.001) or dual energy x-ray absorptiometry (DEXA; P < 0.001). Total-body water increased in the first 6 months whether measured by bioelectrical impedance (P < 0.001) or deuterium dilution (P = 0.002). Fat mass measured by DEXA (P < 0.001), skinfold thicknesses (P < 0.001), and waist/hip ratio (P = 0.001) decreased in the first 6 months. Most changes in body composition were complete by 3 months of treatment and maintained to 12 months. Whole-body bone mineral density (BMD) (by DEXA) was unaffected by GH treatment. Self-reported quality of life was considered good before treatment, and beneficial treatment effects were observed for energy, pain, and emotional reaction as assessed by the Nottingham Health Profile. In the initial 6 months, adverse effects were reported by 84% of patients in the GH and 75% in the placebo group, with more symptoms relating to fluid retention in the GH group (48% vs. 30%; P = 0.016). Such symptoms were mild and resolved in 70% of patients despite continued treatment. Resting blood pressure did not change over the initial 6 months. In summary, GH treatment in adults with GH deficiency resulted in 1) prominent increases in serum IGF-I at the doses employed, in some cases to supraphysiological levels; 2) modest decreases in total- and low-density lipoprotein cholesterol, together with substantial reductions in total-body and truncal fat mass consistent with an improved cardiovascular risk profile; 3) substantial increases in lean tissue mass; and 4) modest improvements in perceived quality of life. The excessive IGF-I response and side-effect profile suggests that lower doses of GH may be a required for prolonged GH treatment in adults with severe GH deficiency.

Thyroid dysfunction following radiotherapy for head and neck cancer.

PURPOSE: To determine the frequency of hypothyroidism (both subclinical and clinical) following external beam radiotherapy to the whole of the thyroid gland in the treatment of squamous cell cancers of the head and neck. METHODS AND MATERIALS: One hundred and four patients who had completed radiotherapy 30 days to 5 years earlier (84 patients) or who were scheduled for radiotherapy (20 patients) had a single measurement of serum-free thyroxine and thyroid stimulating hormone levels between August 1991 and May 1992. RESULTS: None of the 20 patients assessed prior to treatment showed thyroid dysfunction. Twenty of 84 (23.8%) previously treated patients had subclinical (9.5%) or clinical (14.3%) hypothyroidism. By 5 years, up to 40% of patients may become hypothyroid. Thyroid underactivity was significantly more common in patients having both laryngectomy (including hemi-thyroidectomy) and radiotherapy compared to radiotherapy alone (p < 0.001). Hypothyroidism had not been suspected clinically in any patient tested. CONCLUSION: In view of the frequency and potential morbidity of this complication, thyroid function testing should become a routine part of posttreatment follow-up for these patients.

Amiodarone compared with iodine exhibits a potent and persistent inhibitory effect on TSH-stimulated cAMP production in vitro: a possible mechanism to explain amiodarone-induced hypothyroidism.

Amiodarone (AMD) is a powerful anti-arrhythmic drug used for the treatment of a wide variety of cardiac arrhythmias and its most striking feature is its high iodine content. Thyroid dysfunction is a limiting side-effect of the drug and both AMD-induced hypothyroidism (AIH) and AMD-induced thyrotoxicosis (AIT) are reported. To examine the hypothesis that altered bioavailability of iodine is a contributing event in the pathogenesis of AIH, we compared the effects of AMD and inorganic iodine in vitro on events involved in the process of thyroid autoregulation. FRTL-5 cells and JP26 CHO cells (transfected with the human TSH receptor) were exposed to AMD or NaI in the presence of TSH, and cAMP production was measured as an indicator of cellular function. Forskolin and cholera toxin were also used to determine the possible target sites of AMD and iodide. Our results indicated that there was a difference between the effects of AMD versus those of physiological doses of iodide. The inhibitory effects of AMD occurred at lower concentrations of iodide than those seen in the NaI-treated cells. The effects of AMD were irreversible indicating a possible persistence of the Wolff-Chaikoff effect due to a constant high intracellular iodide level. The inhibitory effects of AMD (also seen at supraphysiological doses of iodide) were partially overcome by forskolin but not by cholera toxin indicating an effect on TSH receptor interactions with the other signal transduction elements such as G proteins and adenylate cyclase. The persistence of the Wolff-Chaikoff effect through loss of autoregulation may be a mechanism of the observed hypothyroidism in some patients taking AMD. The combined effects of the constant release of iodide together with the drug toxicity may be the mechanism for the observed effects.

Thyroid ultrasound is the best prevalence indicator for assessment of iodine deficiency disorders: a study in rural/tribal schoolchildren from Gujarat (Western India).

OBJECTIVES: (i) To assess the severity of iodine deficiency disorders (IDD), (ii) to determine the aetiology of IDD in Gujarat, (iii) to identify the best prevalence indicator of IDD, and (iv) to compare thyroid volume (TV) results with the WHO International reference. METHODS: Five hundred and thirty schoolchildren (6-15 years) were studied from two districts (Baroda and Dang) and data were collected on dietary habits and parameters such as height, weight, thyroid size by palpation and ultrasonography, urinary iodine (UI), and blood thyroid stimulating hormone (TSH). Drinking water was analyzed for iodine content and food articles for goitrogens. RESULTS: In Gujarat children median UI (interquartile range)=56 (30-96)microg/l, mean TSH=1.71 +/- 2.10mU/l, goiter by palpatio n = 30%, and median TV = 27.8 (23-35)ml. Females had lower median UI (48 (27-82) microg/l) and higher mean TSH levels (2.0 +/- 2.5mU/l) than males. Applying the WHO ultrasonography reference to Gujarat children resulted in an enlarged TV-for-body surface area in almost 100% of subjects. Ninety-nine percent of females and 95% of males had enlarged TV-for-age. Three to eight times larger TV were seen in all subjects as compared with European children. Dang children were severely malnourished. Flavonoids like vitexin, glucosyl vitexin and apigenin were detected in pearl millet. Apigenin was never identified in pearl millet. Dang district water was lacking in iodine content. CONCLUSIONS: IDD is a severe public health problem in Gujarat. Baroda district is a new pocket of IDD. High amounts of dietary flavonoids in Baroda and Dang districts, and lack of iodine in Dang water, account for IDD. TV measurement by ultrasound is the best prevalence indicator of IDD.

Impact of protein energy malnutrition on thyroid size in an iodine deficient population of Gujarat (India): Is it an aetiological factor for goiter?

OBJECTIVE: To assess the severity of protein energy malnutrition (PEM) in iodine deficient subjects and to assess the impact of PEM on thyroid size. METHODS: 1002 subjects (530 school-aged children and 472 adults) were assessed for PEM by direct anthropometric measurements of height, weight, triceps skinfold (TSF) thickness, mid upper arm circumference (MUAC) and thigh circumference (TC), and derived indices of body surface area (BSA), body mass index (BMI), and Z-scores for weight-for-age (WAZ), height-for-age (HAZ), and weight-for-height (WHZ). Severity of PEM was based on the World Health Organization (WHO) criteria and the threshold on the Waterlow classification. Thyroid size was measured by ultrasonography to determine the thyroid volume (TV). Linear regression analysis was performed between TV and anthropometric parameters. RESULTS: Children had severe PEM as evident from the WHO percentage prevalence of stunting (HAZ<-2SD)=64% (where <-2SD is the Z-score deficit), wasting (WHZ<-2SD)=43%, underweight (WAZ<-2SD)=82% and BMI<16 kg/m=90%. Waterlow classification showed that children were either stunted or wasted, or stunted and wasted, or stunted and obese. Nearly 100% (529/530) of the children had goiter as evidenced from enlarged TV-for-BSA when compared with the WHO reference. There was a weak but statistically significant (P<0.05) positive correlation between TV and BSA, weight, height, MUAC, TC and HAZ but a negative correlation between TV and WHZ, BMI and TSF (r=-0.1-0.2). Adults had PEM as evident from BMI<18.5 kg/m in 54% subjects. Median MUAC=22.7 cm reveals prolonged severe PEM. Eighty-two percent had enlarged TV (>20 ml). There was a significant (P=0.01) negative correlation between TV and MUAC. CONCLUSIONS: (i) The severity of acute (wasting) and chronic (stunting) PEM is very high in Gujarati children. They are stunted or wasted, or stunted and wasted, or stunted and obese. Gujarati adults are thin with low protein and fat reserves. (ii) Anthropometric parameters showed a significant (P<0.001) correlation (r=0.1-0.2) with thyroid size. (iii) Higher prevalence of goiter may be due to macro-nutrient malnutrition (PEM) in the face of micro-nutrient malnutrition (iodine deficiency disorders, IDD).

Amiodarone induces a different pattern of ultrastructural change in the thyroid to iodine excess alone in both the BB/W rat and the Wistar rat.

Amiodarone (AMD)-induced toxicity can be a life-threatening complication which limits the use of amiodarone as an anti-arrhythmic agent. The aim of the present study was to determine the nature of AMD toxicity by comparing ultrastructural changes induced by AMD and equivalent amounts of iodide in two animal models, the Wistar and the autoimmune BB/W rat. Rats were divided into control (water), AMD- (30 mg AMD/kg) or iodide-treated (10 mg/kg) groups. Thyroids were removed at 15 weeks and processed for electron microscopy. We found that AMD induced specific ultrastructural changes of thyroid cytotoxicity in both rat models, which were distinct compared with changes induced by excess iodide alone. Specific changes included marked distortion of thyroid architecture, evidence of necrosis and apoptosis, inclusion bodies, lipofuscinogenesis and markedly dilated endoplasmic reticulum (ER). Our data indicate that AMD is directly cytotoxic to the thyroid an effect mediated by disruption of subcellular organelle function. ER dilatation is suggestive that AMD cytotoxicity may be mediated through disruption of the protein sorting pathways leading to a drug-induced form of ER storage disease. The predilection of the thyroid to AMD may be explained by the additive effects of excess iodine and AMD drug toxicity on protein sorting pathways.

Iodide induced lymphocytic thyroiditis in the BB/W rat: evidence of direct toxic effects of iodide on thyroid subcellular structure.

A high dietary iodine intake accelerates the development of lymphocytic thyroiditis (LT) in the BB/W rat. Our previous studies have defined the temporal sequence of the immunological events triggered by excess iodide intake in these animals. It was still not clear, however, whether these observed immunological changes were a direct effect on immune effector cells, or whether they represented a secondary response to a toxic effect of iodine on thyroid tissue. In the present study, the effect of excessive iodine intake on the subcellular structure of the BB/W rat thyroid gland, particularly, whether iodide had a toxic effect independent of its immune response has been examined. BB/W rats were exposed, prenatally through maternal drinking water, to excessive iodide at two doses (Moderate 3 x 10(-6) M iodide/l; High 3 x 10(-3) M iodide/l); a third group of BB/W rats was given tap water; till 12 weeks postnatal age. Two groups of Wistar rats received high dose iodide water or tap water for the same period of time and served as controls. Thyroid gland ultrastructure was determined by electron microscopic (EM) examination. Thyroid 125I uptake and perchlorate discharge tests were also performed in separate experiments. We found that thyroid glands of non-iodine supplemented Wistar rats were morphlogically normal under EM. There were no overt changes in the iodide treated Wistar rats. By contrast, iodide treated BB/W rats exhibited marked accumulation of secondary lysosomes and lipid droplets; markedly swollen and disrupted mitochondria and extreme dilatation of rough endoplasmic reticulum (RER).(ABSTRACT TRUNCATED AT 250 WORDS)

Iodine induced lymphocytic thyroiditis in the BB/W rat: early and late immune phenomena.

The effect of iodine excess on thyroid function and on the immunological sequence of events leading to lymphocytic thyroiditis (LT) was studied in the NB subline of BB/W rats to determine the mechanisms by which the level of iodine intake influences the development of LT in this animal model. Iodine supplemented water (500 micrograms/l, Group 1 or 500 mg/l, Group 2) or non-iodine supplemented tap water (Group 3) was given to breeding pairs and their offspring ad libitum. A Wistar rat group, also given tap water (Group 4) served as controls. To determine the immunological sequence of events, the phenotypic nature of the infiltrating thyroid lymphocytes was examined by specific immunoperoxidase staining in BB/W and Wistar rats at 6, 9, 12, and 15 weeks. Antigen-presenting cells and class II (Ia) antigen expression on thyrocytes were also examined. The first immunological event apparent in the iodine-treated BB/W rats was a sharp increase in the number of Ia positive dendritic cells at 9 weeks compared with control BB/W and Wistar rats. In the iodine excess groups dendritic cells were associated with scattered areas of lymphocytic infiltration, comprising predominantly T helper cells (W3/25). T suppressor cells (OX 8) and IL-2 receptor positive activated T-cells (OX 39) were both present in small numbers. B-cells (OX 12) were absent. In addition, thyrocytes did not exhibit Ia antigen expression. By contrast, lymphocytic infiltration was not found at 9 weeks in control BB/W rats.(ABSTRACT TRUNCATED AT 250 WORDS)