Chapter 071. Vitamin and Trace Mineral Deficiency and Excess (Part 1) pot

Chapter 071. Vitamin and Trace Mineral Deficiency and Excess (Part 1) Harrison's Internal Medicine > Chapter 71. Vitamin and Trace Mineral Deficiency and Excess Vitamin and Trace Mineral Deficiency and Excess: Introduction Vitamins and trace minerals are required constituents of the human diet since they are either inadequately synthesized or not synthesized in the human body. Only small amounts of these substances are needed for carrying out essential biochemical reactions (e.g., acting as coenzymes or prosthetic groups). Overt vitamin or trace mineral deficiencies are rare in Western countries due to a plentiful, varied, and inexpensive food supply; however, multiple nutrient deficiencies may appear together in persons who are chronically ill or alcoholic. Moreover, subclinical vitamin and trace mineral deficiencies, as diagnosed by laboratory testing, are quite common in the normal population—especially in the geriatric age group. Famine, emergency-affected and displaced populations, and refugees are at increased risk for protein-energy malnutrition and classic micronutrient deficiencies (vitamin A, iron, iodine), as well as for thiamine (beriberi), riboflavin, vitamin C (scurvy), and niacin (pellagra) overt deficiencies. Body stores of vitamins and minerals vary tremendously. For example, vitamin B 12 and vitamin A stores are large, and an adult may not become deficient for 1 or more years after being on a depleted diet. However, folate and thiamine may become depleted within weeks when eating a deficient diet. Therapeutic modalities can deplete essential nutrients from the body; for example, hemodialysis removes water-soluble vitamins, which must be replaced by supplementation. There are several roles for vitamins and trace minerals in diseases: (1) deficiencies of vitamins and minerals may be caused by disease states such as malabsorption; (2) both deficiency and excess of vitamins and minerals can cause disease in and of themselves (e.g., vitamin A intoxication and liver disease); and (3) vitamins and minerals in high doses may be used as drugs (e.g., niacin for hypercholesterolemia). The hematologic-related vitamins and minerals (Chaps. 98, 100) are considered only briefly in this chapter, as are the bone-related vitamins and minerals (vitamin D, calcium, phosphorus; Chap. 346), since they are covered elsewhere (Tables 71-1, 71-2, and Fig. 71-1). Table 71-1 Principal Clinical Findings of Vitamin Malnutrition Nutrient Clinical Finding Dietary Level per Day Associated with Overt Deficiency in Adults Contributing Factors to Deficiency Thiamine Beriberi: neuropathy, muscle weakness and wasting, cardiomegaly, edema, ophthalmoplegia, confabulation <0.3 mg/1000 kcal Alcoholism, chronic diuretic use, hyperemesis Riboflavin Magenta tongue, angular stomatitis, <0.6 mg — Nutrient Clinical Finding Dietary Level per Day Associated with Overt Deficiency in Adults Contributing Factors to Deficiency seborrhea, cheilosis Niacin Pellagra: pigmented rash of sun- exposed areas, bright red tongue, diarrhea, apathy, memory loss, disorientation <9.0 niacin equivalents Alcoholism, vitamin B 6 deficiency, riboflavin deficiency, tryptophan deficiency Vitamin B 6 Seborrhea, glossitis convulsions, neuropathy, depression, confusion, microcytic <0.2 mg Alcoholism, isoniazid Nutrient Clinical Finding Dietary Level per Day Associated with Overt Deficiency in Adults Contributing Factors to Deficiency anemia Folate Megaloblastic anemia, atrophic glossitis, depression, homocysteine <100 µg/d Alcoholism, sulfasalazine, pyrimethamine, triamterene Vitamin B 12 Megaloblastic anemia, loss of vibratory and position sense, abnormal gait, dementia, impotence, loss of bladder and bowel control, homocysteine, <1.0 µg/d Gastric atrophy (pernicious anemia), terminal ileal dise ase, strict vegetarianism, acid reducing drugs (e.g., H 2 blockers) Nutrient Clinical Finding Dietary Level per Day Associated with Overt Deficiency in Adults Contributing Factors to Deficiency methylmalonic acid Vitamin C Scurvy: petechiae, ecchymosis, coiled hairs, inflamed and bleeding gums, joint effusion, poor wound healing, fatigue <10 mg/d Smoking, alcoholism Vitamin A Xerophthalmia, nigh tblindness, Bitot's spots, follicular hyperkeratosis, impaired embryonic development, <300 µg/d Fat malabsorption, infection, measles, alcoholism, protein- Nutrient Clinical Finding Dietary Level per Day Associated with Overt Deficiency in Adults Contributing Factors to Deficiency immune dysfunction energy malnutrition Vitamin D Rickets: skeletal deformation, rachitic rosary, bow ed legs; osteomalacia <2.0 µg/d Aging, lack of sunlight exposure, fat malabsorption, deeply pigmented skin Vitamin E Peripheral neuropathy, spinocerebellar ataxia, skeletal muscle atrophy, retinopathy Not described unless underlying contributing factor is present Occurs only with fat malabsorption, or genetic abnormalities of vitamin E metabolism/transport Nutrient Clinical Finding Dietary Level per Day Associated with Overt Deficiency in Adults Contributing Factors to Deficiency Vitamin K Elevated prothrombin time, bleeding <10 µg/d Fat malabsorption, liver disease, antibiotic use . Chapter 071. Vitamin and Trace Mineral Deficiency and Excess (Part 1) Harrison's Internal Medicine > Chapter 71. Vitamin and Trace Mineral Deficiency and Excess Vitamin and Trace. malabsorption; (2) both deficiency and excess of vitamins and minerals can cause disease in and of themselves (e.g., vitamin A intoxication and liver disease); and (3) vitamins and minerals in high. removes water-soluble vitamins, which must be replaced by supplementation. There are several roles for vitamins and trace minerals in diseases: (1) deficiencies of vitamins and minerals may be caused