Plasma zinc concentration

Domestic sheep (Ovis aries) fed a low-zinc diet (2.2 mg Zn/kg DW diet) for 50 days, when compared to those fed a zinc-adequate diet (33 mg Zn/kg DW diet), excreted less zinc (<4 mg daily vs. 23 to 25), consumed less food (409 g daily vs. 898), and had lower plasma zinc concentrations (0.18 mg/L vs. 0.53 to 0.58) a reduction in plasma alkaline phosphatase activity and an increase in plasma zinc binding capacity were also noted (Khandaker and Telfer 1990). Sensitive indicators of zinc deficiency in lambs include significant reductions in plasma alkaline phosphatase activity and plasma zinc concentrations signs were clearly evident in lambs fed 10.8 mg Zn/kg DW diet for 50 to 180 days (Vergnes et al. 1990). A normal diet for lambs contains 124 to 130 mg Zn/kg DW ration vs. 33 for adults (Vergnes et al. 1990). One recommended treatment for zinc-deficient sheep is ruminal insertion of zinc-containing boluses every 40 days bolus zinc release is about 107 mg daily (Khandaker and Telfer 1990). 

Sex hormones can cause changes in metal metabolism, including both increased and reduced plasma zinc concentrations and raised serum copper however, serum magnesium is not affected (191). The clinical importance of these effects is not known. 

Zinc concentrations in the erythrocyte and plasma decreased significantly (p < 0.01) during zinc restriction in comparison to the stabilization levels. During the early phase of zinc repletion a slight increase in erythrocyte and plasma zinc levels was noted, but these values were not statistically significant in comparison to the zinc-restriction levels. A marked increase in erythrocyte and plasma zinc concentration was observed during the... 

Changes in the plasma zinc concentration were observed within 4 to 6 weeks and correlated with the severity of dietary zinc restriction. Thus, plasma zinc may be very useful in assessment of zinc status in humans provided infections, myocardial infarction, intravascular hemolysis, and acute stress are ruled out ( ). As a result of infections, myocardial Infarction, and acute stress, zinc from the plasma compartment may... 

A number of important and, as yet, unexplained discrepancies are apparent in tissue zinc concentrations in this syndrome. Patients with chronic renal disease, with clinical signs and symptoms of zinc deficiency show consistently elevated red blood cell zinc levels (40-42) whereas plasma zinc concentrations have been reported as either low, normal or elevated (40-44). Patients with Kwashiorkor and symptoms of zinc deficiency have... 

Figure 4. The mean increment in plasma zinc concentration ( SEM) at hourly intervals after 7-8 subjects per group received zinc sulfate alone or with ferrous sulfate in an aqueous solution of CocaCola with the amounts of minerals shown. The distinct treatments constituted Fe/Zn ratios of 0, 1 1, 2 1, and 3 1. (Reproduced with permission from Ref. 50. Copyright 1981, American Society for...

As metabolic balance techniques cannot separate the contribution of malabsorption from that of endogenous loss, collaborators at the Division of Nutrition, University of Sao Paolo Medical School at Rlbeirao Preto, Brazil and I undertook to assess Sn Zn interaction using the change-in-plasma-zinc approach. Healthy volunteers received 12.5 mg of zinc as 55 mg of zinc sulfate in 100 ml of CocaCola either alone (control) or with 25, 50 or 100 mg of tin as stannous chloride to constitute 2 1, 4 1 and 8 1 Sn/Fe ratios. We measured the change in plasma zinc concentration at hourly Intervals over a 4-h period. None of the treatments produced any significant decrement in the uptake of zinc in plasma (61) (Table V). Thus, unlike the dramatic effect of even lesser ratios of Fe/Zn (above), the plasma appearance of zinc was unaffected by soluble, inorganic, divalent tin ions. 

A 17-year-old man developed fatigue after taking large daily doses of zinc supplements for 6-7 months in an attempt to treat his acne (7). He initially took 50 mg/ day, but because his acne did not improve he increased the dosage to 100 mg tds. He had anemia and neutropenia. His plasma zinc concentration was 1.95 (reference range 0.50-0.95) pg/ml 1 month after withdrawal and 1.69 pg/ml 1 month later. His plasma copper concentration was 0.12 (reference value 0.90-2.35) pg/ml. When his anemia and neutropenia had resolved 4 months later, the zinc and copper concentrations had returned to normal. 

Exudation of large amounts of zinc-protein complexes into the intestinal lumen also may contribute to the decrease in plasma zinc concentrations which occur in patients with inflamamtory disease of the bowel. It seems likely that protein losing enteropathy because of other causes also may impair zinc homeostasis. Another potential cause of negative zinc balance is a massive loss of intestinal secretions. 

Renal Disease. The potential causes of conditioned deficiency of zinc in patients with renal disease include proteinuria and failure of tubular reabsorption. In the former instance, the loss of zinc—protein complexes across the glomerulus is the mechanism. In the latter an impairment in the metabolic machinery of tubular reabsorption attributable to a genetic abnormality or to toxic substances would result in zinc loss. While low plasma zinc concentrations have been described in patients with massive proteinuria, no reports of low plasma levels of zinc in patients with tubular reabsorption defects have appeared in literature (9). 

In patients with renal failure, the occurrence of conditioned zinc deficiency may be the result of a mixture of factors, which at present are ill defined. If 1,25-dihydroxycholecalciferol plays a role in the intestinal absorption of zinc, an impairment in its formation by the diseased kidney would be expected to result in malabsorption of zinc. It seems likely that plasma and soft tissue concentrations of zinc may be "protected in some individuals with renal failure by the dissolution of bone which occurs as a result of increased parathyroid activity in response to low serum calcium. In experimental animals, calcium deficiency has been shown to cause release of zinc from bone. In some patients who are successfully treated for hyperphosphatemia and hypocalcemia, the plama zinc concentration may be expected to decline because of the deposition of zinc along with calcium in bone. Thus, in the latter group in particular, a diet low in protein and high in refined cereal products and fat would be expected to contribute to a conditioned deficiency of zinc. Such a diet would be low in zinc. The patients reported by Mansouri et al. (37), who were treated with a diet containing 20-30 g of protein daily and who had low plasma concentrations of zinc, appear to represent such a clinical instance. Presumably the patients of Halsted and Smith (38) were similarly restricted in dietary protein. In other patients with renal failure whose dietary protein was not restricted, plasma zinc concentration were not decreased. Patients on dialysis had even higher levels, particularly... 

Figure 2. The change in plasma zinc concentration mean se) at 60-min intervals for 4 h after various graded doses of ascorbic acid mixed with 110 mg of ZnSOj THzO (56). Key 0-------0, 0.5 g of...

Figure 3. The change in plasma zinc concentration (mean se) over 4 h for five subjects consuming 475 mg of ZnSOj ZHgO (containing 108 mg of zinc) mixed into 120 g of black bean gruel (56). The mean was consumed either alone ( ----- ), or with 2.0 g of ascorbic acid ( — — ), by five sub-...

There are also changes in the binding proteins in plasma as a result of the disease process. Since serum albumin falls in association with any acute iUness, this inevitably leads to a fall in plasma zinc concentration. Similarly a reduction in retinol-binding-protein concentration as part of the APR or protein malnutrition also leads to a fall in serum retinol levels, whatever the amount of retinol stores within the liver. 

Serum zinc concentrations are generally 5% to 15% higher than plasma because of osmotic fluid shifts from the blood cells when various anticoagulants are used. Plasma zinc concentrations exhibit both circadian and postprandial fluctuations. Concentrations decrease after food and are higher in the morning than in the evening. 

G12. Greaves, M., and Boyde, T. R. C., Plasma zinc concentrations in patients with psoriasis, other dermatoses and venous leg ulcerations. Lancet ii, 1019-1020 (1967). 

Hambidge KM, Waleavens PA, Casey CE, Brown RM and Bender C (1979) Plasma zinc concentrations of breast-fed infants. J Pediatr 94 607-608. 

As stated earlier plasma zinc concentration is low in a wide range of conditions (Halstead and Smith, 1970). One effect of stress , mediated by ACTH and cortisol, is to reduce plasma zinc. This is part of the acute phase response to accidental or surgical injury, the effect lasting for several days. Bacterial or viral infections have a similar effect. There is recent evidence that the fall in plasma zinc is part of a complex series of metabolic events induced by the humoral factors such as Interleukin 1 (Dinarello, 1982) which in turn activates interleukin-6 the active factor responsible for induction of liver... 

Acute zinc deficiency, with the signs of skin disease, abdominal pain and the other effects listed in Table 2, is seen at plasma zinc concentrations of less than 0.5 mg/L. The adults who developed the acrodermatitis-like condition during prolonged IVN had plasma zinc levels of 0.3-0.5 mg/L at the time when they began to gain body weight. 

The test usually conducted to determine body zinc is the measurement of plasma zinc concentration. However, plasma zinc concentrations do not seem to reflect the concentration found in the liver parenchyma (Goksu Ozsoylu, 1986 Sato et al., 2005). This may be explained by the fact that there are very efficient homeostatic mechanisms to correct plasma or serum zinc deficiencies, which makes it difficult to diagnose marginal deficiency by using this method. Therefore, the investigation of zinc concentration in liver tissue is important. 

Schneider AC, Pinto RB, Froelich PE et al. Low plasma zinc concentrations in patients with cirrhosis. J Pediatr (Rio J). 2009 85(4) 359-364. 

Lowe, N.M., Woodhouse, L.R., Sutherland, B., Shames, D.M., Burri, B.J., Abrams, S.A., Tumlund, J.R., Jackson, M.J., and King, J.C. (2004) Kinetic parameters and plasma zinc concentration correlate well with net loss and gain of zinc from men. 

The blood contains 6-7 mg/1 zinc, with about 75-88% of this amount in erythrocytes, 12-22% in blood plasma (plasma zinc concentration is about 1 mg/1) and the rest is in the leucocytes and platelets. In blood plasma, the majority of zinc is bound to serum albumin and a smaller part to a2-macroglobulin. The red blood cells contain zinc, mainly in the enzyme carbonate anhydratase. 

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