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Part II Nutrition Assessment, Consequences, and Implications

Iron Level: Serum Iron, Total Iron-Binding Capacity

Normal Value Serum Iron (Fe) (5): ●

Women: 60 to 160 μg/dL; 11 to 29 μmol/L (SI) ( ● Men: 80 to 180 μg/dL; 14 to 32 μmol/L (SI)

Total Iron-Binding Capacity (TIBC) (5): ●

250 to 460 μg/dL; 45 to 82 μmol/L (SI) Nutritional Significance

Most of the iron in the body is found in the hemoglo- bin of the red blood cells. Dietary iron is absorbed in the small intestine and transported to the plasma. In the plasma, iron is bound to transferrin and transported to the bone marrow for production of hemoglobin. The remaining iron is stored as ferritin and hemosiderin in the liver and other tissues for future use. The serum iron reflects the amount of iron bound to transferrin. TIBC is a direct measure of transferrin. When TIBC is not available, transferrin can be directly measured (1).

● ●

Serum Fe levels increase with (1): pernicious anemia aplastic anemia

● hemolytic anemia B-6 deficiency acute hepatitis

● ● ● ● ● ● ● ● ●

repeated transfusions nephritis

excessive iron therapy

hemosiderosis, hemochromatosis iron poisoning hepatic necrosis lead toxicity

Serum Fe levels decrease with (1): ●

iron-deficiency anemia ● ● ● ● ● ● ● ●

acute and chronic infection cancer

protein-energy malnutrition nephrosis

insufficient dietary iron chronic blood loss

inadequate absorption of iron neoplasia

● chronic GI blood loss chronic hematuria

●

The following drugs may increase serum Fe levels (1): ●

● ● ●

chloramphenicol dextran estrogen ethanol

● methyldopa

The following drugs may decrease serum Fe levels (1): ●

●

xholestyramine xolchicine

● adrenocorticotropic hormone (ACTH) deferoxamine methicillin testosterone

● ● ●

TIBC levels increase with (1): ●

●

iron-deficiency anemia polycythemia vera

TIBC levels decrease with (1): ●

hypoproteinemia ● ● ●

inflammatory diseases cirrhosis

hemolytic, pernicious, and sickle cell anemias

Fluoride may increase TIBC levels. Corticotropic hormone and chloramphenicol may decrease TIBC levels (1).

Osmolality, Serum

Normal Values ●

Critical Values ●

Older adults: 285 to 295 mOsm/kg water (5)

Less than 265 mOsm/kg water, greater than 320 mOsm/kg water (5)

Nutritional Significance

Osmolality measures the concentration of particles in a solution. Serum osmolality is increased with dehydra- tion and decreased with overhydration. When serum osmolality increases, the antidiuretic hormone is secreted, which causes more water reabsorption, a more concentrated urine, and a less concentrated serum. When osmolality is low, the body decreases water reabsorption and excretes large amounts of dilute urine (1,5).

Serum osmolality is used to evaluate fluid and electrolyte imbalance, seizures, liver disease, hydration status, and acid-base balance (1,5).