Urinary Zinc Excretion Research Articles

Zinc Nutritional Status of Morbidly Obese Patients Before and After Roux-en-Y Gastric Bypass: A Preliminary Report

Previous researchers have found that the nutritional zinc status in obese and diabetic subjects is altered: low zinc concentrations in plasma and erythrocytes with high urinary zinc excretion were observed. This study assessed the influence of the Roux-en-Y gastric bypass (RYGBP) on the plasma, erythrocyte and urinary zinc concentrations before the beginning of the mineral supplementation. 24 morbidly obese patients were studied before and 2 months after RYGBP (the period in which the patients were still not ingesting mineral supplements). Fast blood sample, 24-hour urine, and 3-day food records were collected in the pre- and postoperative phases. Zinc concentration in the samples was analyzed by flame atomic absorption spectrophotometry, and dietary analysis of the food records were performed using the software Virtual Nutri with the inclusion of zinc concentration in the database for regional foods. Pre- and postoperative results were respectively: plasma 68.0 and 66.3 microg/dL; erythrocytes 36.6 and 43.8 microg/g Hb; urine 884.7 microg/24h and 385.9 microg/24h; and zinc intake 10.5 and 6.7 mg/day. These results suggest that RYGBP changed mainly the zinc erythrocyte and urinary concentrations. As expected, the zinc intake was lower in the postoperative phase, which in the medium and long term, could cause problems for the patients.

Zinc Status of Women with Low Bone Mineral Density Who Receive Calcium Supplements

We evaluated whether a daily high-dose calcium supplement perturbs the zinc status in 23 postmenopausal women (mean age: 63 yr) with low bone mineral density. Plasma and erythrocyte zinc concentrations, plasma bone-specific alkaline phosphatase (BSAP) and 5'-nucleotidase activities, and urinary zinc and calcium excretion were determined first at the end of 4 wk of daily oral calcium (1200 mg) and were measured again at the end of the subsequent 4 wk of daily cosupplementation with calcium (1200 mg) and zinc (30 mg). Mean plasma and erythrocyte zinc concentrations after 4 wk of calcium alone were not significantly different from concentrations after cosupplementation of calcium and zinc. Mean plasma BSAP activities before cosupplementation with zinc was significantly higher than that after zinc (p < 0.02), whereas plasma 5'-nucleotidase activities were not affected by zinc supplementation. Urinary zinc excretion slightly, but significantly, increased after the supplementation of zinc (p < 0.05), whereas calcium excretion remained similar. Our data indicate that a 4-wk zinc supplementation did not significantly improve zinc status. Although limited by the small sample size and short study duration, our data suggest that a daily calcium dose of 1200 mg had no effect on the zinc status of our subjects.

Urinary Zinc Excretion Is Normalized in Primary Arterial Hypertension After Perindopril Treatment

Increased or unchanged urinary zinc excretion has been reported in hypertension. In the present article, this observation was confirmed in a group of 10 untreated hypertensive patients of both sexes that had no diabetes or obesity. The 24-h zinc excretion was significantly different between the patients: 7.46+/-3.01 micromol and healthy controls: 5.19+/-2.19 micromol (p<0.025). After a 1-mo treatment with 4 mg perindopril per day, a decrease of urinary zinc was observed until it reached levels not significantly different from those of the healthy controls (5.98 +/- 2.13 micromol). The decrease was significantly different from that of the pretreatment values (p<0.05).

Zinc metabolism and surgical trauma.

Several investigations have shown that zinc deficiency impairs wound healing in surgical wounds and in chronic ulcers. It is also well established that surgical trauma produces a sharp decrease in serum zinc concentration. It has not been clearly shown that this decrease is due to a rise in urinary excretion. In the present investigation the relationship between urinary zinc excretion and the fall in serum zinc postoperatively was studied in 38 patients. Older patients usually had low preoperative serum zinc concentrations. Preoperative zinc substitution is therefore suggested for such patients.

Metabolism after injury. I. Effects of severity, nutrition, and environmental temperatue on protein potassium, zinc, and creatine.

AbstractThe effect of an environmental temperature of 28–30°C. and a relative humidity of 35–45 per cent on the protein metabolic response to injury of one or more major long bones of the lower limbs has been studied in 29 male patients and 28 similar controls housed at 20–22°C. The metabolic response was reduced at the higher temperature compared with the controls, the more severely injured showed a greater metabolic response than the less severely injured, and the ameliorating influence of environmental temperature was more noticeable in the former. The metabolic response seems to be principally one of catabolism of muscle, with increased urinary excretions of potassium, creatine, and zinc in the urine correlating well with those of nitrogen at 20°C. but not at 30°C. The response (i.e., catabolism of muscle) was not affected by post-injury diet at 20°C. ambient temperature. There was a reduction in the disturbance of the plasma proteins.In general, the patients tolerated the warm drier conditions. Owing to the intrinsic difficult in assessing minor changes in bone healing it was not possible to assess what, if any, beneficial change occurred in the fracture site. From our experimental observations on the rat and the work of others on burned patients the reduction in heat production at the higher ambient temperature is accompanied by an enhanced rate of healing of surface wounds.

Metabolism after injury. 2. Effect of a dryish and warm environment on skin temperatures and electrolyte responses.

Abstract Patients with moderate to severe fractures of the major long bones of the lower limb had generally warmer extremities if nursed in cubicles with a dryish (35–45 per cent relative humidity) and warm (29–30° C.) environment than if maintained at a normal temperature of 20–24° C. The additional heat was applied soon after the period of shock was over and was then provided for a further 10–12 days thereafter. The effect of a higher temperature in reducing the protein catabolic response to injury–which seems mainly to involve an increase in the catabolism of some muscle proteins accompanied by increased urinary excretions of potassium, creatine, and zinc–has already been described (Cuthbertson, Fell, Smith, and Tilstone, 1972). The effects of a warmer atmosphere on oral and skin temperatures over various surfaces are described in the present paper and these effects are compared with those found when extra bed coverings are applied under normal ward environmental conditions (20–22° C.). By the application of such heat the skin temperature of the extremities can be raised several degrees; that of the large toes by as much as 12° C. By the use of extra bed coverings conductive losses can undoubtedly be diminished, particularly at normal temperatures. Oral, axillary, and frontal and mastoid process temperatures are not apparently influenced by a higher environmental temperature but appear to be mainly related to the degree of traumatic fever. The advantage of the higher environmental temperature over extra bed coverings is presumed to be mainly in reducing total resting heat production from resting to basal values by providing thermoneutral conditions. Apart from a significant reduction in the rise in serum potassium around the fifth day after injury and a reduction in the normal increased urinary excretion of potassium previously noted, there were no significant changes in the concentration of other serum electrolytes as a result of the higher environmental temperature, nor were the other characteristic electrolyte patterns of urinary excretion altered by the change in the ambient temperature. There were also no distinctive differences in the pattern of urinary amino-acids at the two temperatures.

Severe Anemia and Neutropenia Associated With Hyperzincemia and Hypercalprotectinemia

Calprotectin, also known as the S100A8/A9 or MRP8/14 complex, is a major calcium-binding protein in the cytosol of neutrophils, monocytes, and keratinocytes. It differs from other S100 proteins in its zinc-binding capacity. The authors describe a 4-year-old girl with severe anemia, neutropenia, inflammation, and severe growth failure. Bone marrow examination showed moderate dyserythropoiesis. No hemolysis, iron deficiency, hemoglobinopathies, immunologic diseases, or autoantibodies were detected. Serum levels of copper and ceruloplasmin were within the normal range, although the serum zinc concentration was markedly increased (310 microg/dL). Urinary zinc excretion and erythrocyte zinc concentrations were within the normal range. Family studies showed normal zinc and copper plasma levels. The patient's plasma calprotectin concentration showed a 6,000-fold increase (2,900 mg/L) compared with normal values. The calprotectin concentration is known to be elevated in many inflammatory conditions but is generally below 10 mg/L and thus far below the levels reported in this patient. The authors describe this case as an inborn error of zinc metabolism caused by dysregulation of calprotectin metabolism, which mainly presented with the features of microcytic anemia and inflammation.

Effect of Hypothyroidism on Intestinal Zinc Absorption and Renal Zinc Disposal in Five-Sixths Nephrectomized Rats

Both hypothyroid (Hypo) and hypozincemia are commonly observed in patients and animals with chronic renal failure (CRF). In CRF whether the hypothyroid plays a role in the pathogenesis of hypozincemia is unclear. This study is designed to investigate the effects of hypothyroid on intestinal zinc absorption and urinary zinc excretion in 5/6 nephrectomized (Nx) rats, because plasma zinc balance is attained through a controlled rate of intestinal uptake as well as renal reabsorption. Intestinal zinc absorption was carried out in jejunum and ileum segments by an in vivo perfusion technique and the renal zinc disposal was evaluated by a conventional method using a standard formula to calculate the zinc tubular reabsorption and the excretion of urinary zinc in 5/6 Nx rats with hypothyroidism. The Hypo-NxT rats showed a significant decrease in the rate of intestinal zinc absorption and in the response of plasma zinc levels during intestinal zinc perfusion compared with Eu-NxT rats. They also had significantly lower levels of mucosal zinc and MT as well as lower content of liver zinc than Eu-NxT rats after intestinal zinc perfusion for 80 min. Hypo-NxT rats showed low plasma zinc levels, but had a similar output of pancreaticobiliary zinc and excretion of 24-h urine zinc compared with the Eu-NxT rats. When 2% alcohol intestinal perfusion was used to produce water diuresis, the Hypo-NxT rats presented a higher excretion of urinary zinc than the Eu-NxT rats did, especially during 2% alcohol intestinal zinc perfusion. In the Hypo-NxT rats, the lower plasma zinc levels may thus result from the hypothyroid because it reduces intestinal zinc absorption. Increasing the urine flow rate may aggravate the reduction of plasma zinc level in Hypo-NxT rats because of the increased excretion of urinary zinc.

Excretion of Urinary Cadmium, Copper, and Zinc in Cadmium-Exposed and Nonexposed Subjects, with Special Reference to Urinary Excretion of β&lt;SUB&gt;2&lt;/SUB&gt;-microglobulin and Metallothionein

The objectives of this study were to examine the association between urinary excretion of cadmium (U-Cd), copper (U-Cu), and zinc (U-Zn) and the severity of two different indicators of renal toxicity (urinary excretion of beta2-microglobulin [U-beta2-MG] and metallothionein [U-MT]) in Cd-exposed subjects compared to controls, and to assess the physiologic mechanisms by which the exposure to environmental Cd affects U-Cd, U-Cu, and U-Zn. The target population included 3508 Cd-exposed and 294 nonexposed participants who received a health survey conducted among the population of the Kakehashi River basin. Increases of U-Cd, U-beta2-MG, and U-MT in the Cd-exposed population were observed relative to excretion of these substances in controls. Regression analysis using a general linear model revealed that the correlations between U-Cd or U-Cu, and U-beta2-MG and between U-Cd, U-Cu or U-Zn, and U-MT were statistically significant in both sexes, but the correlation between U-Zn and U-beta2-MG excretion was significant only in men. These results suggest U-Cd and U-Cu is affected by dysfunction in renal tubular absorption (indicated by U-beta2-MG), whereas not only U-Cd and U-Cu but also U-Zn appear to be a function of renal cellular desquamation (indicated by U-MT).

Comparison of zinc excretion and biochemical markers of bone remodelling in the assessment of the effects of alendronate and calcitonin on bone in postmenopausal osteoporosis

Objectives: The aim of this study was to determinate the clinical usefulness of urinary bone resorption markers, urinary zinc excretion, and other biochemical markers in postmenopausal women with osteoporosis. We also evaluated the effects of alendronate and calcitonin therapies on biochemical markers of bone remodeling and urinary zinc excretion over a 6-month period. Subjects and methods: The study design was a randomized placebo controlled study. The patients were randomly assigned to receive alendronate (10 mg/day; 45 patients) or calcitonin (200 IU/day; 45 patients) or placebo (45 patients) for 6 months. All patients received supplemental calcium (1000 mg/day). To assess bone resorption, we measured excretion of cross-linked N-telopeptides of Type I collagen (uNTx); urinary zinc concentrations and standard chemistry determinations were also measured; and osteocalcin (sOC) was measured as a marker of bone formation. All parameters were measured before therapy and again after 1, 3, and 6 months in all groups. Results: A statistically significant decrease occurred in the levels of sOC, uZn, and uNTx after 3 and 6 months in patients receiving calcitonin therapy ( P < 0.05). sOC, uZn, and uNTx levels in the calcitonin group were significantly lower after three and 6 months from both placebo and baseline values of calcitonin group. In the alendronate group, a statistically significant decrease was observed in the levels of uNTx and uZn after 1 month and in the sOC, uZn, and uNTx after 3 and 6 months from both placebo and baseline values of alendronate group ( P < 0.05). uNTx, sOC, and uZn decreased about 44%, 36%, and 33%, respectively, in the calcitonin group and about 53%, 51%, and 38%, respectively, in the alendronate group below baseline values 6 months after initiating treatment. In the placebo group, there was no significant decrease in sOC, uZn, and uNTx during the course of the study. Conclusion: Our study suggests that in postmenopausal women with osteoporosis, both alendronate and calcitonin reduce the concentrations of uNTx, uZn, and sOC, the effect of the alendronate dose administered being significantly earlier and more pronounced. Measurement of uNTx, uZn, and sOc might be a useful biochemical method of observing the positive clinical effect following alendronate or calcitonin therapy in postmenopausal women.

The effect of calcitonin on biochemical markers and zinc excretion in postmenopausal osteoporosis

Objectives: A double-blind, randomized, placebo-controlled trial was conducted in women with postmenopausal osteoporosis to evaluate effects on biochemical markers and urinary excretion of zinc (Zn) of calcitonin therapy. Methods: Patients were required to have a bone mineral density (BMD) of 2.5 S.D. or more below the young adult mean either at the postero-anterior lumbar spine or at the femoral neck. Subjects were eligible for our study if they were 50 years or older, with at least 5 years of menopause, and in good general health as determined by medical history and a routine clinical blood analysis. The patients were randomly assigned to receive intranasal salmon calcitonin (200 IU/day; 50 patients) or placebo (50 patients). All patients received supplemental calcium (1000 mg/day). Additionally, 40 age-matched, demographically similar, healthy postmenopausal women were also selected as controls. Measurements of cross-linked N-telopeptides of type I collagen (uNTx), osteocalcin (sOC), and urinary zinc concentration were done. All parameters were measured before therapy and again after 1, 3 and 6 months. Results: After 3 and 6 months of treatment, a higher decrease of most indices was observed in the calcitonin group. A statistically significant decrease occurred in the levels of sOC, uNTx and uZn after 3 and 6 months in patients receiving calcitonin therapy ( P < 0.05). Levels of sOC and uNTx in calcitonin group were significantly different after 3 and 6 months from both placebo and baseline values of calcitonin group ( P < 0.05). Levels of sOC, uNTx and uZn decreased about 40, 46 and 37%, respectively, in calcitonin group at 6 months after the start of treatment. Conclusions: Our study suggests that values of uNTx, uZn and sOC were significantly lower in the patient group than those in control group and in postmenopausal women with osteopororsis, calcitonin reduces the concentrations of uNTx, uZn and sOC.

Metabolic adaptations to low zinc intakes in premenarcheal girls

Zinc deficiency is increasingly recognized as an important cause of mortality and morbidity. Children in developing countries are at especially high risk because of relatively low zinc intakes and poor bioavailability. We assessed the effect of 2-wk adaptation to low zinc intake (4 mg/d) on fractional zinc absorption, endogenous fecal zinc excretion, and urinary zinc excretion. Sixteen healthy 9-14-y-old girls were studied twice in random order after 2-wk adaptation to diets providing either 12 mg/d (high) or 4 mg/d (low) zinc. Fractional zinc absorption and endogenous fecal zinc excretion were measured with use of established stable isotope techniques. Plasma zinc was not significantly lower during the low dietary intake period (1.06 +/- 0.18 mg/L) than during the high dietary intake period (1.14 +/- 0.23 mg/L, P = 0.30). Endogenous fecal zinc excretion was significantly lower during the low intake period (1.08 +/- 0.62 mg/d) than during the high intake period (1.82 +/- 0.95 mg/d, P < 0.026), but there was no significant change in fractional zinc absorption (30.6% +/- 12.4% compared with 26.6% +/- 9.0%, P = 0.32) or urinary zinc excretion (0.68 +/- 0.35 mg/d compared with 0.59 +/- 0.24 mg/d, P = 0.30). Approximate zinc balance was significantly lower during the low-intake period than during the high-intake period (P = 0.007) and significantly (P < 0.0001) less than zero. Short-term zinc restriction in premenarcheal girls leads to a significant decrease in endogenous fecal zinc excretion, which was inadequate to restore normal zinc balance.

Zinc metabolism in adolescents with Crohn's disease.

Low serum zinc concentrations have been reported in Crohn's disease (CD) and overt zinc deficiency has been described, but little is known about the effect of CD on zinc metabolism in adolescents. The aim of this study was to measure zinc absorption, endogenous fecal zinc excretion, urinary zinc excretion, and zinc balance in children with stable CD and in matched controls. Subjects were 15 children, ages 8-18 y, with stable CD, and 15 healthy matched controls. Subjects were adapted to diets providing 12 mg/d elemental zinc for 2 wk, and then admitted for a 6-d metabolic study. Stable zinc isotopes were given intravenously and orally, and urine and feces collected for 6 d. Fractional zinc absorption, endogenous fecal zinc excretion, and zinc balance were calculated using established stable isotope methods. In subjects with CD, zinc absorption (10.9% +/- 6.1 versus 23.4 +/- 15.8, p = 0.008) and plasma zinc concentration (0.85 mg/dL +/- 0.15 versus 1.25 +/- 0.35, p = 0.004) were significantly reduced, compared with controls. Despite this, there were no significant differences in endogenous fecal zinc excretion (2.0 mg +/- 1.5 versus 1.5 +/- 1.5, p = 0.34) or urinary zinc excretion (0.9 mg +/- 0.7 versus 1.0 +/- 0.7, p = 0.47). Zinc balance was significantly lower in CD (-1.5 mg +/- 1.5) than in controls (+0.6 mg +/- 3.1, p < 0.0001). In conclusion, adolescents with CD have significantly reduced zinc absorption. Despite this, they were unable to reduce endogenous fecal zinc excretion to restore normal zinc balance and had a significantly worse zinc balance and lower plasma zinc concentration than controls.

Intestinal Absorption and Biliary Secretion of Zinc in Rats with Chronic Renal Failure

Background/Aims: In chronic renal failure (CRF), zinc deficiency is partially attributed to decreased intestinal zinc absorption, but the mechanism of this decrease in intestinal zinc absorption is obscure. Therefore, the objective of this study was to investigate the cause of decreased intestinal zinc absorption in a uremic rat model using an in vivo perfusion technique as well as to evaluate the effect of intestinal zinc perfusion on the secretion of biliary zinc in normal and CRF rats. Methods: CRF was induced by five-sixths nephrectomy (Nx). During zinc sulfate perfusion, absorption of zinc in the small intestine and the response of plasma zinc level were measured. After intestinal zinc perfusion for 80 min, the concentrations of zinc and metallothionein (MT) in the intestinal mucosal and liver tissue were assayed. The secretion of biliary zinc and the excretion of urinary zinc were also determined before and after zinc sulfate perfusion. The results were compared with those obtained from 10 sham-operated normal rats. Results: The CRF rats showed a significant decrease in the rate of intestinal zinc absorption and in the response of plasma zinc levels during intestinal zinc perfusion. They also had significantly higher levels of mucosal zinc and MT than sham-operated normal rats, but their contents of liver zinc were significantly lower than those of sham-operated normal rats after zinc sulfate perfusion. CRF rats showed a low plasma zinc level and a high urinary zinc excretion in baseline levels, but had similar output of basal biliary zinc as compared with sham-operated normal rats. Zinc sulfate perfusion in the small intestinal was not found to increase the secretion of biliary zinc and the excretion of urinary zinc, either in normal or CRF rats. Conclusion: In the CRF rat, the reduction of intestinal zinc absorption may result from reduced mucosal zinc efflux from the basolateral membrane into plasma. These data also suggest that the absorbed zinc from the gastrointestinal tract is mostly taken up by the liver or other tissues, and is less excreted in bile juice and urine.

Role of Urinary Zinc and Copper on Calcium Oxalate Stone Formation

Introduction: It is considered that many factors may play a role in urolithiasis. Experimental and clinical studies have shown that zinc has an inhibitory effect on urolithiasis. Materials and Methods: In this study, urinary zinc and copper were measured in 27 healthy controls and 30 calcium oxalate stone formers. Results: Urinary zinc excretion was significantly higher (p < 0.001) in stone formers than healthy controls (2,575 ± 274 and 960 ± 80 mg/day, respectively). There was no significant difference in urinary copper excretion between healthy controls and stone formers (32.3 ± 3.5 and 33.3 ± 3.2 µg/day, respectively). Conclusions: According to our results, the potent inhibitory effect of urinary zinc excretion on urolithiasis could be reviewed.

The effects of losartan and losartan/hydrochlorothiazide fixed combination on zinc and magnesium metabolism in patients with hypertension

Drug combinations with thiazides (TZD) are common in the treatment of hypertension. We have previously shown that treatment with ACE inhibitors increased urinary Zinc (Zn) excretion, while TZD enhance urinary Zn and magnesium (Mg) losses. The effects of angiotensin receptor blockers on Zn and Mg metabolism are unknown. Sixteen Caucasian hypertensives (10 men, age 51±3 years,(SEM), body mass index 31±2 kg/m2), received losartan (LOS) 50mg (Ocsaar, MSD) for 4 weeks and LOS 50mg+hydrochlorothiazide (HCT) 12.5mg (Ocsaar plus, MSD) for the next 4 weeks. Serum, peripheral blood mononuclears (PBMC) and 24-hour urinary Zn and Mg concentrations were determined at baseline, after LOS and after LOS+HCT treatments. LOS treatment significantly increased urinary Zn excretion (from 0.24±0.07 mcg/mg creatinine to 0.43±0.08 mcg/mg creatinine, p=0.01), and was associated with a significant decrease in PBMC Zn levels (from 13.8±0.8 mcg/mg protein to 12.4±0.8 mcg/mg protein, p=0.01). LOS+HCT further increased urinary Zn excretion (from 0.43±0.08 mcg/mg creatinine after LOS to 0.74±0.2 mcg/mg creatinine after LOS+HCT, p=0.04), but had no effect on PBMC Zn concentrations. Serum Zn concentrations remained unchanged after both treatments. Serum and PBMC Mg concentrations, and urinary excretion of Mg remained unchanged too. Treatment with LOS, induces increased urinary Zn excretion and Zn depletion in hypertensive patients. HCT has an additive effect. LOS and LOS+HCT had no effect on Mg metabolism. Clinical Pharmacology & Therapeutics (2004) 75, P12–P12; doi: 10.1016/j.clpt.2003.11.046

Zinc Nutritional Status and Its Relationships with Hyperinsulinemia in Obese Children and Adolescents

A perturbation of zinc metabolism has been noted in subjects with obesity. The present work intends to investigate whether the zinc nutritional status is associated with hyperinsulinemia in obesity. A study was carried out in a group of obese children and adolescents (n=23) and compared to a control group (n=21), both between 7 and 14 yr of age. Software analyzed diet information from 3-d food records. Body composition was evaluated by body mass index (BMI), bioelectrical impedance, and skin-fold measurements. Zinc nutritional status was evaluated by Zn determination in plasma, erythrocyte, and 24-h urine, by atomic absorption spectrophotometry (lambda=213.9 nm). Insulin was measured by radioimmunoassay (Linco Res). Diets consumed by both groups had marginal concentrations of zinc. Zinc concentrations in plasma and erythrocytes were significantly lower in the obese group. Urinary zinc excretion and serum insulin were significantly higher in the same group, although the insulinemia and the parameters of zinc nutritional status were not significantly correlated. As a result, considering that zinc is part of the synthesis and secretion of this hormone, an assessment is necessary of the possible participation of the oligoelement in the mechanisms of insulin resistance, commonly present in obese patients.

Effects of smoking and lead exposure on proximal tubular integrity among egyptian industrial workers

Background The hazards of occupational lead exposure are well documented. Tissue damage produced by lead is slow and progressive. The renal system is one of the systems primarily affected by lead. The present study aimed to evaluate renal proximal tubular functional and structural integrity among lead-exposed and cigarette-smoking male Egyptian workers. This study was extended to investigate the effect of lead exposure and cigarette smoking on urinary excretion of copper (Cu) and zinc (Zn). Methods Participants included in the present study were 156 male workers grouped as follows: i) 75 lead non-exposed workers subgrouped into G 1 that consisted of 36 non-smokers (age, 39.08±6.65 years) and G 2, which included 39 smokers (age, 43.87±9.93 years); ii) 45 lead-exposed workers (work duration <20 years) subgrouped into G 3 that consisted of 25 non-smokers (age, 37.40±3.76 years) and G 4, which included 20 smokers (age, 38.40±4.95 years), and iii) 36 lead-exposed workers (work duration ≥ 20 years) subgrouped into G 5 that consisted of 16 non-smokers (age, 45.94±4.19 years) and G 6, which included 20 smokers (age, 45.70±2.25 years). Functional integrity of proximal tubules was studied by determining urinary level of low-molecular-weight protein α 1-microglobulin (α 1M), and structural integrity was investigated by measuring urinary activities of the lysosomal enzyme N-acetyl-β-D-glucosaminidase (NAG) and the cytoplasmic enzyme glutathione S-transferase (GST). Urinary concentrations of Pb, Cu, Zn, and creatinine were also determined. Results Data of the present investigation showed increased urinary excretion of all measured urinary parameters among lead-exposed workers in comparison with non-exposed workers whether they were non-smokers or smokers (G 3 vs. G 1, G 5 vs. G 1, G 4 vs. G 2, and G 6 vs. G 2), with greater elevation among lead-exposed smokers than among lead-exposed non-smokers (G 4 vs. G 3, G 6 vs. G 5). In addition, there was a greater increase in levels of all urinary parameters among workers with work duration ≥20 years than in those with <20 years' work duration (G 6 vs. G 4, G 5 vs. G 3). Conclusions Lead exposure in Egyptian workers causes damage to renal proximal tubules and results in its dysfunction. Cigarette smoking has a nephrotoxic effect and also is synergistic to lead nephrotoxicity on urinary excretion of GST and NAG, as well as Pb.

Renal tubular dysfunction in β-thalassemia minor

Background: Persons with β-thalassemia minor usually are symptomless. However, we previously reported renal tubular dysfunction in a patient with β-thalassemia minor. The aim of this study is to investigate renal function in patients with β-thalassemia minor. Methods: Forty-one subjects with β-thalassemia minor and 20 sex- and age-matched healthy subjects were enrolled in the study. For analysis, patients were divided into 2 groups: group A, all patients with anemia (n = 19), and group B, patients without anemia (n = 22). Blood and 24-hour urine samples were obtained for hematologic and biochemical analysis. Results: Anemic patients had increased urinary zinc excretion (Uzinc) and fractional excretion of sodium (FENa) and uric acid (FEUA) compared with both controls and patients without anemia. Hemoglobin levels correlated significantly in a negative manner with Uzinc, FENa, and FEUA in patients with β-thalassemia minor. However, serum lactate dehydrogenase levels correlated significantly in a positive manner with the same parameters. In addition, 6 of 41 patients (14.6%) with β-thalassemia minor showed significant signs of renal tubulopathy, such as hypercalciuria, decreased tubular reabsorption of phosphorus with hypophosphatemia, hypomagnesemia with renal magnesium wasting, hypouricemia with renal uric acid wasting, and tubular proteinuria. Conclusion: Proximal renal tubular dysfunction is not rare in patients with β-thalassemia minor.

Effect of Silica Exposure on Urinary Excretion of Copper and Zinc

Occupational exposure to silica could lead to renal histological alterations in the glomeruli and proximal tubules. We investigated urinary excretion of copper and zinc and its possible relationship to renal alterations and work duration among nonsmoking, silica-exposed workers. Thirty-six control subjects (age, 39.08 +/- 6.65 years) and 48 silica-exposed workers (age, 36.79 +/- 7.33 years) were included in the present study. The exposed workers were grouped into workers with <10 years' work duration (n = 9; age, 29.0 +/- 1.50 years) and workers with > or =10 years' work duration (n = 39; age, 38.59 +/- 6.94 years). Glomerular function was assessed by measuring urinary level of microalbumin, and proximal tubular reabsorption function was assessed by measuring urinary level of alpha1-microglobulin. Structural integrity of proximal tubules was studied by measuring urinary activity of cytosolic enzyme glutathione S-transferase (GST). Also, urinary levels of copper, zinc, and creatinine were measured. All measured urinary parameters were significantly increased among silica-exposed workers compared with control subjects. A significant correlation was observed between urinary levels of each of copper and zinc with the glomerular and proximal tubular functional and structural urinary parameters as well as work duration. Occupational silica exposure may lead to increased urinary loss of copper and zinc as protein-metal complex, and the urinary level of these essential trace elements may be a marker for renal dysfunction. The urinary excretion of GST may be a useful marker for proximal tubular injury.