Determination and comparison of urinary iodine levels in patients with age-related macular degeneration and healthy volunteers

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Abstract

Abstract. To investigate the urine iodine level of patients with dry- and wet-type age-related macular degeneration (ARMD) and to compare with those of normal healthy volunteers. ARMD is a leading cause of severe vision loss in developed countries and the pathogenesis has not yet been fully clarified. The ciliary body of the eye and lacrimal gland concentrate iodine, and their antioxidative capacities are increased by iodine because of its antioxidant properties. Urine samples were received from 23 normal healthy volunteers (group I), 23 patients with wet-type (group II) and, 23 patients with dry-type ARMD (group III). Urinary iodine concentration was determined spectrophotometrically using the Sandell-Kolthoff reaction. The iodine levels were significantly lower in group II (4.04 ± 1.12 µg/dL) and in group III (9.73 ± 1.85 µg/dL) compared to group I (the control group: 17.21 ± 1.65 µg/dL) (p ˂ 0.001). The iodine levels of group II were lower than those of group III (p ˂ 0.001). Tight junctions between retina pigment epithelial cells promoted by iodine assist in the prevention of fluid passage between the neural retina and the retinal pigment epithelium. Low iodine levels in patients with ARMD may be a possible indication of the degeneration of these tight junctions. Therefore, iodine deficiency could be a risk factor for neovascular ARMD. Urinary iodine excretion is used as the most convenient, rapid, and low-cost laboratory marker to determine iodine deficiency, and it may be used to follow up ARMD. Iodine supplementation might be useful to prevent the development of macular edema associated with ARMD. 

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Risk factors associated with age-related macular degeneration. A case-control study in the age-related eye disease study: Age-Related Eye Disease Study Report Number 3.

(2000)

To investigate possible risk factors for age-related macular degeneration (AMD) in participants in the Age-Related Eye Disease Study (AREDS). Case-control study. Of the 4757 persons enrolled in AREDS, 4519 persons aged 60 to 80 years were included in this study. The lesions associated with AMD ranged from absent in both eyes to advanced in one eye. Stereoscopic color fundus photographs of the macula were used to place participants into one of five groups, based on the frequency and severity of lesions associated with AMD. Participants with fewer than 15 small drusen served as the control group. Staged model building techniques were used to compare each of the four case groups with the control group. Increased age was a consistent finding of all four of the case groups compared with the control group, and all the following associations were age adjusted. Persons with either intermediate drusen, extensive small drusen, or the pigment abnormalities associated with AMD (group 2) were more likely to be female, more likely to have a history of arthritis, and less likely to have a history of angina. Persons with one or more large drusen or extensive intermediate drusen (group 3) were more likely to use hydrochlorothiazide diuretics and more likely to have arthritis. Hypertension, hyperopia, presence of lens opacities, and white race were also found more frequently in this group as well as in persons with neovascular AMD (group 5). Only persons in group 5 were more likely to have an increased body mass index, whereas persons with geographic atrophy (group 4) as well as those in groups 3 and 5 were more likely to have completed fewer years in school or to be smokers. Those with geographic atrophy were also more likely to use thyroid hormones and antacids. Our findings for smoking and hypertension, which have been noted in previous studies, suggest that two important public health recommendations, the avoidance of smoking and the prevention of hypertension, may reduce the risk of developing AMD. Other associations, such as those for hyperopia, lens opacities, less education, female gender, increased body mass index, and white race, which have been noted in other studies, are also seen in the AREDS population. The increased use of thyroid hormones and antacids in persons with geographic atrophy and the increased likelihood of arthritis or hydrochlorothiazide use in persons with one or more large drusen or extensive intermediate drusen have not been previously reported and need additional investigation.

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Zinc, copper, and blood pressure: Human population studies

William E. Carpenter, Derek Lam, Glenn M. Toney … (2013)

Summary Copper and zinc are essential trace biometals that regulate cardiovascular homeostasis, and dysregulation of these metals has been linked to vascular diseases, including hypertension. In this article, we review recent human population studies concerning this topic, focusing on: 1) the relationship between blood pressure and levels of zinc and copper; 2) correlations between trace metals, the renin-angiotensin system, obesity, and hypertension; 3) the relationship between environmental metal pollution and the development of hypertension; and 4) methods commonly employed to assay zinc and copper in human specimens. Moreover, based on the findings of these studies, we suggest the following topics as the basis for future investigations: 1) the potential role of environmental metal pollution as a causal factor for hypertension; 2) metal profiles within specific pathogenic subsets of patients with hypertension; 3) standardizing the experimental design so that the results between different studies are more comparable; and 4) the requirement for animal experiments as complementary approaches to address mechanistic insight that cannot be studied in human populations.

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The value of the chloride: sodium ratio in differentiating the aetiology of metabolic acidosis.

D. Taylor, A Durward, I Murdoch … (2001)

Stewart's physicochemical approach to acid-base balance defines the aetiology of a metabolic acidosis by quantifying anions of tissue acids (TA), which consist of unmeasured anions (UMA) and/or lactate. We hypothesised that an increase in TA during metabolic acidosis would lead to a compensatory fall in the plasma chloride (Cl) relative to sodium (Cl:Na ratio) in order to preserve electro-neutrality. Thus, the Cl:Na ratio could be used as a simple alternative to the anion gap in identifying raised TA. Two hundred and eighty two consecutive patients who were admitted to our Paediatric Intensive Care were enrolled in the study. We obtained 540 samples (admission n = 282, 24 h n = 258) for analysis of blood chemistry, lactate and quantification of TA and UMA. Samples were subgrouped into those with metabolic acidosis (standard bicarbonate 3 mEq/l). Metabolic acidosis occurred in 46% of samples, of which 52.3% (120/230) had increased UMA. The dominant component of TA was UMA rather than lactate, and these two components did not always rise in tandem. Our hypothesis of relative hypochloraemia was supported by a lower Cl:Na ratio (P 0.79) excluded TA (PPV 81%, LR 4.5). Base deficit (BD) and lactate performed poorly. In metabolic acidosis due to TA, plasma Cl concentration decreases relative to sodium. The Cl:Na ratio is a simple alternative to the AG for detecting TA in this setting.