SUMMARY Reference ranges for albumin bound and a2-macroglobulin bound zinc concentrations have been determined in a study of sera obtained from 134 healthy adults. The concentrations of zinc bound to a2-macroglobulin were remarkably constant with a mean (+SD) of 2-4 + 0-6 ,umol/l; the variations in total serum zinc concentrations were almost entirely accounted for by variations in the zinc associated with albumin. There were no sex related differences in the transport of zinc in serum; neither was this sensitive to the use of oral contraceptives. These data provide a baseline for further investigations into the effects of zinc deficiency on the serum transport of the metal.There is increasing recognition that secondary zinc deficiency states may complicate a wide variety of clinical conditions.' Research in this field has been inhibited, however, by difficulties associated with the assessment of body zinc availability, which is commonly attempted using analyses for the total zinc in samples of plasma or serum. Only the most florid deficiencies of zinc can be reliably diagnosed by such means since equivocally reduced plasma zinc concentrations may be found in many circumstances in which no deficiency of the metal is suspected.2 On some occasions these findings are the result of a transfer of zinc from the plasma to intracellular sites; this commonly occurs acutely after operations or after other similarly stressful events.3 Even in more stable clinical circumstances difficulties may arise because almost all of the plasma zinc is bound to proteins, which are themselves subject to changes of concentration in response to factors unrelated to the availability of the metal.Because of these latter problems attempts have been made to characterise the distribution of zinc between its plasma protein ligands, both in health and disease. Unfortunately, the results of these studies have often been contradictory, not only with regard to the identities of the protein species which bind zinc in plasma, but also with regard to the distribution of zinc between them. The disparity of Accepted for publication 13 June 1984 these findings almost certainly results from analytical errors arising from three principal sources: incomplete protein separation, disruption of metalprotein interactions during the process of protein fractionation, and contamination with exogenous zinc.We have recently shown that the zinc contained in human serum is bound almost exclusively to only two proteins-albumin and a2-macroglobulin45-and we have developed a rapid and reliable micromethod for the determination of these two zincprotein species.4 The present study was undertaken to investigate the concentrations of albumin bound and a2-macroglobulin bound zinc in the sera of healthy human subjects to provide control data for use in subsequent studies of zinc deficiency states. Subjects and methods SUBJECTSWhole blood was obtained from 134 normal healthy volunteers: 86 men aged 18-62 years and 48 women aged 19-60 years. Eleven of the women who participate...
Background: Maternal subclinical hypothyroidism is a cause of poor neurodevelopment outcome in the offspring. Although iodine deficiency is the most common cause of hypothyroidism world wide, there are no screening programmes for it in the United Kingdom where the population is assumed to be iodine replete. Objective: To determine the prevalence of reduced iodine intake by measuring urinary iodide concentrations in pregnant and non-pregnant women from the north east of England. Methods: Urinary iodide excretion (UIE) rate was estimated using inductively coupled mass spectrometry in 227 women at 15 weeks gestation and in 227 non-pregnant age matched controls. A reduced intake of iodine is indicated by a concentration in urine of less than 50 mg/l or less than 0.05 mg iodine/mmol creatinine. Results: Eight (3.5%) pregnant women and 13 (5.7%) controls had a reduced iodine/creatinine ratio. These values were higher when UIE was expressed as iodine concentration: 16 (7%) and 20 (8.8%) respectively. Ninety (40%) of the pregnant women had a UIE of 0.05-0.10, which is consistent with borderline deficiency. Conclusion: In this study, 3.5% of pregnant women had evidence of iodine deficiency, and 40% may be borderline deficient. Larger scale studies are required to estimate the true prevalence of iodine deficiency in the United Kingdom.
Increasing Pt concentrations from vehicle catalysts have been reported from a number of countries. Analysis of Pt and Pd in soils and road dusts taken from areas of high and low traffic flows in SE England show concentrations of Pt in the range < 0.30-40.1 ng g-1 and Pd in the range < 2.1-57.9 ng g-1. Higher concentrations of Pt are associated with high traffic densities. Samples taken from streets of lower traffic flows were found to contain the lower concentrations of the ranges. Pilot studies of Pt concentrations in blood and urine using ICP-MS have been carried out. Platinum concentrations in whole blood were: precious metal workers, 780-2170, mean 1263 pmol l-1 (0.152-0.423, mean 0.246 microgram l-1); motorway maintenance workers, 645-810, mean 744 pmol l-1 (0.126-0.158, mean 0.145 microgram l-1); Imperial College staff, 590-713, mean 660 pmol l-1 (0.115-0.139, mean 0.129 microgram l-1). Platinum concentrations in urine in pmol Pt per mmol creatinine were: precious metal workers, 122-682, mean 273 [0.21-1.18, mean 0.47 microgram Pt (g creatinine)-1]; motorway maintenance workers, 13-78, mean 33.7 [0.022-0.135, mean 0.058 microgram Pt (g creatinine)-1]; Imperial College staff, 28-130, mean 65.6 [0.048-0.224, mean 0.113 microgram Pt (g creatinine)-1]. Detection limits were 0.03 microgram l-1 for both blood and urine. The possible health effects of increasing Pt in the environment are discussed. Platinum provides an excellent example of the significance of speciation in metal toxicity. Platinum allergy is confined to a small group of charged compounds that contain reactive ligand systems, the most effective of which are chloride ligand systems. Metallic Pt is considered to be biologically inert and non allergenic and since the emitted Pt is probably in the metallic or oxide form, the sensitising potential is probably very low. Platinum from road dusts, however, can be solubilised, and enter waters, sediments, soils and the food chain. There is at present no evidence for any adverse health effects from Pt in the general environment, particularly allergic reactions.
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