Washington Manual of Medical Therapeutics
Nutrient Requirements
Nutrient Requirements is a topic covered in the Washington Manual of Medical Therapeutics.
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General Principles
Energy
- Total daily energy expenditure (TEE) is composed of resting energy expenditure (normally ∼70% of TEE), the thermic effect of food (normally ∼10% of TEE), and energy expenditure of physical activity (normally ∼20% of TEE).
- Use of predictive equations can provide a reasonable estimate of daily energy requirements that should be modified based on the factors that affect the patient’s metabolic rate.
- Malnutrition and hypocaloric feeding may decrease resting energy expenditure to 15%–20% below expected for actual body size, whereas metabolic stressors, such as inflammatory diseases or trauma, often increase energy requirements by ∼30%–50%.
- The Harris–Benedict equation provides a reasonable estimate of resting energy expenditure (in kilocalories [kcal] per day) in healthy adults. It takes into account the effects of body size and lean tissue mass (which are influenced by gender and age) on energy requirements and can be used to estimate total daily energy needs in hospitalized patients (where W is the weight in kilograms, H the height in centimeters, and A is the age in years).1
- Men = 66 + (13.7 × W ) + (5 × H ) − (6.8 × A)
- Women = 665 + (9.6 × W ) + (1.8 × H ) − (4.7 × A)
- Energy requirements per kilogram of body weight are inversely related to body mass index (BMI) (Table 2-1). The lower range within each category should be considered in insulin-resistant, critically ill patients unless they are depleted in body fat.
- Ideal body weight can be estimated based on height
- For men: 106 + 6 lb for each inch over 5 ft
- For women, 100 + 5 lb for each inch over 5 ft
Table 2-1: Estimated Energy Requirements for Hospitalized Patients Based on Body Mass Index
| Body Mass Index (kg/m2) | Energy Requirements (kcal/kg/d) |
| 15 | 35–40 |
| 15–19 | 30–35 |
| 20–24 | 20–25 |
| 25–29 | 15–20 |
| ≥30 | <15 |
Note: These values are recommended for critically ill patients and all obese patients; add 20% of total calories in estimating energy requirements in non–critically ill patients.
Protein
- Protein intake of 0.8 g/kg/d meets the requirements of 97% of the adult population.
- Protein requirements are affected by several factors, including the amount of nonprotein calories provided, overall energy requirements, protein quality, baseline nutritional status, and the presence of inflammation and metabolic stressors (Table 2-2).
- Inadequate amounts of any essential amino acid results in inefficient utilization.
- Illness increases the efflux of amino acids from skeletal muscle; however, increasing protein intake to >1.2 g/kg/d of prehospitalization body weight in critically ill patients may not reduce the loss of lean body mass.2
Table 2-2: Recommended Daily Protein Intake
| Clinical Condition | Protein Requirements (g/kg IBW/d)a |
| Normal | 0.8 |
| Metabolic stress (illness/injury) | 1.0–1.5 |
| Acute renal failure (undialyzed) | 0.8–1.0 |
| Hemodialysis | 1.2–1.4 |
| Peritoneal dialysis | 1.3–1.5 |
IBW, ideal body weight.
aAdditional protein intake may be needed to compensate for excess protein loss in specific patient populations such as those with burn injury, open wounds, and protein-losing enteropathy or nephropathy. Lower protein intake may be necessary in patients with chronic renal insufficiency who are not treated by dialysis and certain patients with hepatic encephalopathy.
Essential Fatty Acids
- Humans lack the desaturase enzyme needed to produce the ω-3 and ω-6 fatty acids. Therefore, linoleic acid should constitute at least 2% and linolenic acid at least 0.5% of the daily caloric intake to prevent deficiency.
- The plasma pattern of increased triene-to-tetraene ratio (>0.4) can be used to detect essential fatty acid deficiency.
Carbohydrate
Certain tissues, such as bone marrow, erythrocytes, leukocytes, renal medulla, eye tissues, and peripheral nerves, cannot metabolize fatty acids and require glucose (∼40 g/d) as a fuel. Endogenous protein and glycerol from lipid stores can undergo gluconeogenesis to supply glucose-requiring organs.
Major Minerals
Major minerals such as sodium, potassium, and chloride are important for ionic equilibrium, water balance, and normal cell function.
Micronutrients (Trace Elements and Vitamins)
Trace elements and vitamins are essential constituents of enzyme complexes. The recommended dietary intake for trace elements, fat-soluble vitamins, and water-soluble vitamins is set at two standard deviations above the estimated mean as to meet the needs of 97% of the healthy population.
See Table 2-3 for specifics regarding the assessment of micronutrient nutritional states as well as signs and symptoms of micronutrient deficiency and toxicity.
Table 2-3: Trace Minerals, Fat-Soluble Vitamins, and Water-Soluble Vitamins: Recommended Daily Intake, Deficiency, At-Risk Populations, Toxicity, and Status Evaluation
| Nutrient | Recommended Daily Enteral Intake3/Parenteral Intake4 | Signs and Symptoms of Deficiency5,6,7,8,9,10,11,12,13,14,15,16 | Populations at Risk for Deficiency | Signs and Symptoms of Toxicity | Status Evaluation3,17 |
| Chromium (Cr3+) | 30–35 μg/10–15 μg | Glucose intolerance, peripheral neuropathya | Nonea,5 | PO: gastritis IV: skin irritation Cr6+: (steel, welding) lung carcinogen if inhaled | Chromiums |
| Copper (Cu2+) | 900 μg/300–500 μg | Hypochromic normocytic or macrocytic anemia (rarely microcytic), neutropenia, thrombocytopenia, diarrhea, osteoporosis/pathologic fracturesa Intrinsic: Menkes disease18 | Chronic diarrhea, high-zinc/low-protein diets17,19 | PO: gastritis, nausea, vomiting, coma, movement/neurologic abnormalities, hepatic necrosis Intrinsic: Wilson disease | Coppers,u Ceruloplasminp |
| Iodine (I−) | 150 μg/70–140 μg (not routinely added) | Thyroid hyperplasia (goiter) + functional hypothyroidism Intrinsic in utero: cretinism, poor CNS development, hypothyroidism | Those without access to fortified salt, grain, milk, or cooking oil20 | Deficiency: causes hypothyroidism Excess: acutely causes hypothyroidism; chronic excess: hyperthyroidism | TSHs, iodineu (24-h intake and iodine: Cr ratio are more representative than a single sample) Thyroglobulins6,20 |
| Iron (Fe2+,3+) | 8 mg/1.0–1.5 μg (not routinely added) | Fatigue, hypochromic microcytic anemia, glossitis, koilonychia | Reproductive-age females, pregnant females, chronic anemias, hemoglobinopathies, post–gastric bypass/duodenectomy, alcoholics | PO or IV: hemosiderosis, followed by deposition in liver, pancreas, heart, and glands Intrinsic: hereditary hemochromatosis | Ferritins, TIBCs, % transferrin saturationc, irons |
| Manganese (Mn2+) | 2.3 mg/60–100 μg | Hypercholesterolemia, dermatitis, dementia, weight lossb | Chronic liver disease, iron-deficient populations | PO: noneb Inhalation: hallucination, Parkinsonian-type symptoms21 | No reliable markers Manganeses does not reflect bodily stores, especially in the CNS |
| Selenium | 55 μg/20–60 μg | Myalgias, cardiomyopathya Intrinsic: Keshan disease (Chinese children), Kashin–Beck disease, myxedematous endemic cretinism22 | Endemic areas of low soil content include certain parts of China and |New Zealand10 | PO: nausea, diarrhea, AMS, irritability, fatigue, peripheral neuropathy, hair loss, white splotchy nails, halitosis (garlic-like odor) | Seleniums, glutathione peroxidase activityb |
| Zinc (Zn2+) | 11 mg/2.5–5.0 mg | Poor wound healing, diarrhea (high fistula risk), dysgeusia, teratogenicity, hypogonadism, infertility, acrofacial and oral skin lesions (glossitis, alopecia), behavioral changes Intrinsic: acrodermatitis enteropathica | Chronic diarrhea, cereal-based diets, alcoholics, chronic liver disease, sickle cell, HIV, pancreatic insufficiency/any intestinal malabsorptive states, fistulas/ostomies, nephrotic syndrome, diabetes, post–gastric bypass/duodenectomy, anorexia, pregnancy19 Intrinsic: acrodermatitis enteropathica | PO: nausea, vomiting, gastritis, diarrhea, low HDL, gastric erosions Competition with GI absorption can precipitate Cu2+ deficiency Inhaled: hyperpnea, weakness, diaphoresis | Zincs,p, alkaline phosphatases (good for those on TPN, but in general Zincs,p hair, RBC, WBC levels can be misleading) Zinc radioisotope studies (most accurate tests at present; limited by cost and availability)7 |
| Vitamin A Retinol | 900 μg/3300 IU | Conjunctival xerosis, keratomalacia, follicular hyperkeratosis, night blindness, Bitot spots, corneal + retinal dysfunction | Any malabsorptive state involving proximal small bowel, vegetarians, chronic liver disease | Acute: teratogenic, skin exfoliation, intracranial hypertension, hepatocellular necrosis Chronic: alopecia, ataxia, cheilitis, dermatitis, conjunctivitis, pseudotumor cerebri, hyperlipidemia, hyperostosis | Retinols, retinol estersp, electroretinogram, liver biopsy (diagnostic for toxicity), retinol binding protein (useful in ESRD; accurately assesses blood levels)23 |
| Vitamin D Ergocalciferol | 5–15 μg/200 IU | Rickets/osteomalacia | Any malabsorptive state involving proximal small bowel, chronic liver disease Of note: those with higher skin melanin content (i.e., darker skin) have low baseline 25-OH vitamin D levels; it is unclear whether this merits their inclusion as an “at-risk” population23 | Hypercalcemia, hyperphosphatemia, which can lead to CaPO4 precipitation, systemic calcification +/− AMS +/− AKI | 25-OH vitamin Ds Of note: lively debate between IOM and Endocrine Society regarding definitions of deficiency, goal serum 25-OH levels, and at-risk populations24,25 |
| Vitamin E (α,γ)-Tocopherol | 15 mg/10 IU | Hemolytic anemia, posterior column degeneration, ophthalmoplegia, peripheral neuropathy Seen in severe malabsorption, abetalipoproteinemia | Any malabsorptive state involving proximal small bowel, chronic liver disease | Possible increased risk in hemorrhagic CVA, functional inhibition of vitamin K–mediated procoagulants | Tocopherol Must account for cholesterol/triglyceride ratio: otherwise, higher cholesterol/triglyceride ratio overestimates vitamin E, lower cholesterol/triglyceride ratio underestimates vitamin E16,c |
| Vitamin K Phylloquinone | 120 μg/150 IU | Hemorrhagic disease of newborn, coagulopathy | Any malabsorptive state involving proximal small bowel, chronic liver disease | In utero: hemolytic anemia, hyperbilirubinemia, kernicterus IV: flushing, dyspnea, hypotension (possibly related to dispersal agent) | Prothrombin timep |
| Vitamin B1 Thiamine | 1.2 mg/6 mg | Irritability, fatigue, headache Wernicke encephalopathy, Korsakoff psychosis, “wet” beriberi, “dry” beriberi | Alcoholics, severely malnourished | IV: lethargy and ataxia | RBC transketolase activityb, thiamineb,u |
| Vitamin B2 Riboflavin | 1.3 mg/3.6 mg | Cheilosis, angular stomatitis, glossitis, seborrheic dermatitis, normocytic normochromic anemia | Alcoholics, severely malnourished | Noneb | RBC glutathione reductase activityp |
| Vitamin B3 Niacin | 16 mg/40 mg | Pellagra dysesthesias, glossitis, stomatitis, vaginitis, vertigo Intrinsic: Hartnup disease | Alcoholics, malignant carcinoid syndrome, severely malnourished | Flushing, hyperglycemia, hyperuricemia, hepatocellular injuryb | N-methyl-nicotinamideu |
| Vitamin B5 Pantothenic acid | 5 mg/15 mg | Fatigue, abdominal pain, vomiting, insomnia, paresthesiasb | Alcoholics3 | PO: diarrhea | Pantothenic acidu |
| Vitamin B6 Pyridoxine | 1.3–1.7 mg/6 mg | Cheilosis, stomatitis, glossitis, irritability, depression, confusion, normochromic normocytic anemia | Alcoholics, diabetics, celiac sprue, chronic isoniazid or penicillamine use15 | Peripheral neuropathy, photosensitivity | Pyridoxal phosphatep |
| Vitamin B7 Biotin | 30 μg/60 μg | Mental status changes, myalgias, hyperesthesias, anorexiac,26 (excessive egg white consumption results in avidin-mediated biotin inactivation) | Alcoholics | Noneb,26 | Biotinp, methyl-citrateu, 3-methyl- crotonyglycineu, 3-hydroxyisovalerateu |
| Vitamin B9 Folic acid | 400 μg/600 μg | Bone marrow suppression, macrocytic megaloblastic anemia, glossitis, diarrhea Can be precipitated by sulfasalazine + phenytoin | Alcoholics, celiac or tropical sprue, chronic sulfasalazine use | PO: may lower seizure threshold in those taking anticonvulsants | Folic acids, RBC folic acidp |
| Vitamin B12 Cobalamin | 2.4 μg/5 μg | Bone marrow suppression, macrocytic megaloblastic anemia, glossitis, diarrhea, posterolateral column demyelination, AMS, depression, psychosis | Vegetarians, atrophic gastritis, pernicious anemia, celiac sprue, Crohn disease, patients postgastrectomy or ileal resection | Noneb | Cobalamin (B12)s, methylmalonic acids,p |
| Vitamin C Ascorbic acid | 90 mg/200 mg | Scurvy, ossification abnormalities Tobacco lowers plasma and WBC vitamin C13 Sudden cessation of high-dose vitamin C can precipitate scurvy | Fruit-deficient diet, smokers,13 ESRD27 | Nausea, diarrhea, increased oxalate synthesis (theoretical nephrolithiasis risk) | Ascorbic acidp, leukocyte ascorbic acid |
AKI, acute kidney injury; AMS, altered mental status; CNS, central nervous system; CVA, cerebrovascular accident; ESRD, end-stage renal disease; IOM, Institute of Medicine; GI, gastrointestinal; HDL, high-density lipoprotein (cholesterol); RBC, red blood cell; TIBC, total iron bonding capacity; TPN, total parenteral nutrition; TSH, thyroid-stimulating hormone; WBC, white blood cell.
Subscript: b, blood; c, calculated; p, plasma; s, serum; u, urine.
aOnly reported in patients on long-term TPN.
bNever demonstrated in humans.
cOnly able to induce under experimental conditions and/or only been able to induce in animals.
Special Considerations
- Both the amount and location of prior gut resection influence nutrient needs. Patients with a reduced length of functional small bowel may require additional vitamins and minerals if they are not receiving parenteral nutrition. Table 2-4 provides guidelines for supplementation in these patients.
- Ileal inflammation, resection, inflammatory bowel disease (IBD), and bypass (ileojejunal bypass) can cause B12 deficiency and bile salt loss. Diarrhea in this setting may be improved with oral cholestyramine.
- Proximal gut resection (stomach or duodenum) via partial gastrectomy, Billroth I and II, duodenal switch/biliopancreatic diversion, Roux-en-Y gastric bypass, pancreaticoduodenectomy (Whipple), and sleeve gastrectomy may impair absorption of divalent cations such as iron, calcium, and copper. Copper deficiency is extremely common in post–gastric bypass patients who do not receive routine supplementation.28
- Patients with excessive gastrointestinal (GI) tract losses require additional fluids and electrolytes. An assessment of fluid losses due to diarrhea, ostomy output, and fistula volume should be made to help determine fluid requirements. Intestinal mineral losses may be calculated by multiplying the volume of fluid loss by the fluid electrolyte concentration (Table 2-5).
- Hyperammonemic encephalopathy is an uncommon but serious complication of Roux-en-Y gastric bypass with an estimated mortality rate of 50%.29 Laboratory hallmarks include elevated ammonia, elevated plasma glutamate, hypoalbuminemia, nutritional and essential amino acid deficiencies, and low zinc.30 It does not appear to resolve with replacement of trace elements. Some reports suggest improvement with total parental nutrition after several months; however, data remain limited.31
Table 2-4: Guidelines for Vitamin and Mineral Supplementation in Patients with Severe Malabsorption
| Supplement | Dose | Route |
| Prenatal multivitamin with mineralsa | 1 tablet daily | PO |
| Vitamin Da | 50,000 units 2–3 times per week | PO |
| Calciuma | 500 mg elemental calcium tid–qid | PO |
| Vitamin B12b | 1 mg daily | PO |
| – | 100–500 μg q1–2 mo | SC |
| Vitamin Ab | 10,000–50,000 units daily | PO |
| Vitamin Kb | 5 mg/d | PO |
| – | 5–10 mg/wk | SC |
| Vitamin Eb | 30 units/d | PO |
| Magnesium gluconateb | 108–169 mg elemental magnesium qid | PO |
| Magnesium sulfateb | 290 mg elemental magnesium 1–3 times per week | IM/IV |
| Zinc gluconate or zinc sulfateb | 25 mg elemental zinc daily plus 100 mg elemental zinc per liter intestinal output | PO |
| Ferrous sulfateb | 60 mg elemental iron tid | PO |
| Iron dextranb | Daily dose based on formula or table | IV |
aRecommended routinely for all patients.
bRecommended for patients with documented nutrient deficiency or malabsorption.
Table 2-5: Electrolyte Concentrations in Gastrointestinal Fluids
| Location | Na (mEq/L) | K (mEq/L) | Cl (mEq/L) | HCO3 (mEq/L) |
| Stomach | 65 | 10 | 100 | – |
| Bile | 150 | 4 | 100 | 35 |
| Pancreas | 150 | 7 | 80 | 75 |
| Duodenum | 90 | 15 | 90 | 15 |
| Mid–small bowel | 140 | 6 | 100 | 20 |
| Terminal ileum | 140 | 8 | 60 | 70 |
| Rectum | 40 | 90 | 15 | 30 |
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General Principles
Energy
- Total daily energy expenditure (TEE) is composed of resting energy expenditure (normally ∼70% of TEE), the thermic effect of food (normally ∼10% of TEE), and energy expenditure of physical activity (normally ∼20% of TEE).
- Use of predictive equations can provide a reasonable estimate of daily energy requirements that should be modified based on the factors that affect the patient’s metabolic rate.
- Malnutrition and hypocaloric feeding may decrease resting energy expenditure to 15%–20% below expected for actual body size, whereas metabolic stressors, such as inflammatory diseases or trauma, often increase energy requirements by ∼30%–50%.
- The Harris–Benedict equation provides a reasonable estimate of resting energy expenditure (in kilocalories [kcal] per day) in healthy adults. It takes into account the effects of body size and lean tissue mass (which are influenced by gender and age) on energy requirements and can be used to estimate total daily energy needs in hospitalized patients (where W is the weight in kilograms, H the height in centimeters, and A is the age in years).1
- Men = 66 + (13.7 × W ) + (5 × H ) − (6.8 × A)
- Women = 665 + (9.6 × W ) + (1.8 × H ) − (4.7 × A)
- Energy requirements per kilogram of body weight are inversely related to body mass index (BMI) (Table 2-1). The lower range within each category should be considered in insulin-resistant, critically ill patients unless they are depleted in body fat.
- Ideal body weight can be estimated based on height
- For men: 106 + 6 lb for each inch over 5 ft
- For women, 100 + 5 lb for each inch over 5 ft
Table 2-1: Estimated Energy Requirements for Hospitalized Patients Based on Body Mass Index
| Body Mass Index (kg/m2) | Energy Requirements (kcal/kg/d) |
| 15 | 35–40 |
| 15–19 | 30–35 |
| 20–24 | 20–25 |
| 25–29 | 15–20 |
| ≥30 | <15 |
Note: These values are recommended for critically ill patients and all obese patients; add 20% of total calories in estimating energy requirements in non–critically ill patients.
Protein
- Protein intake of 0.8 g/kg/d meets the requirements of 97% of the adult population.
- Protein requirements are affected by several factors, including the amount of nonprotein calories provided, overall energy requirements, protein quality, baseline nutritional status, and the presence of inflammation and metabolic stressors (Table 2-2).
- Inadequate amounts of any essential amino acid results in inefficient utilization.
- Illness increases the efflux of amino acids from skeletal muscle; however, increasing protein intake to >1.2 g/kg/d of prehospitalization body weight in critically ill patients may not reduce the loss of lean body mass.2
Table 2-2: Recommended Daily Protein Intake
| Clinical Condition | Protein Requirements (g/kg IBW/d)a |
| Normal | 0.8 |
| Metabolic stress (illness/injury) | 1.0–1.5 |
| Acute renal failure (undialyzed) | 0.8–1.0 |
| Hemodialysis | 1.2–1.4 |
| Peritoneal dialysis | 1.3–1.5 |
IBW, ideal body weight.
aAdditional protein intake may be needed to compensate for excess protein loss in specific patient populations such as those with burn injury, open wounds, and protein-losing enteropathy or nephropathy. Lower protein intake may be necessary in patients with chronic renal insufficiency who are not treated by dialysis and certain patients with hepatic encephalopathy.
Essential Fatty Acids
- Humans lack the desaturase enzyme needed to produce the ω-3 and ω-6 fatty acids. Therefore, linoleic acid should constitute at least 2% and linolenic acid at least 0.5% of the daily caloric intake to prevent deficiency.
- The plasma pattern of increased triene-to-tetraene ratio (>0.4) can be used to detect essential fatty acid deficiency.
Carbohydrate
Certain tissues, such as bone marrow, erythrocytes, leukocytes, renal medulla, eye tissues, and peripheral nerves, cannot metabolize fatty acids and require glucose (∼40 g/d) as a fuel. Endogenous protein and glycerol from lipid stores can undergo gluconeogenesis to supply glucose-requiring organs.
Major Minerals
Major minerals such as sodium, potassium, and chloride are important for ionic equilibrium, water balance, and normal cell function.
Micronutrients (Trace Elements and Vitamins)
Trace elements and vitamins are essential constituents of enzyme complexes. The recommended dietary intake for trace elements, fat-soluble vitamins, and water-soluble vitamins is set at two standard deviations above the estimated mean as to meet the needs of 97% of the healthy population.
See Table 2-3 for specifics regarding the assessment of micronutrient nutritional states as well as signs and symptoms of micronutrient deficiency and toxicity.
Table 2-3: Trace Minerals, Fat-Soluble Vitamins, and Water-Soluble Vitamins: Recommended Daily Intake, Deficiency, At-Risk Populations, Toxicity, and Status Evaluation
| Nutrient | Recommended Daily Enteral Intake3/Parenteral Intake4 | Signs and Symptoms of Deficiency5,6,7,8,9,10,11,12,13,14,15,16 | Populations at Risk for Deficiency | Signs and Symptoms of Toxicity | Status Evaluation3,17 |
| Chromium (Cr3+) | 30–35 μg/10–15 μg | Glucose intolerance, peripheral neuropathya | Nonea,5 | PO: gastritis IV: skin irritation Cr6+: (steel, welding) lung carcinogen if inhaled | Chromiums |
| Copper (Cu2+) | 900 μg/300–500 μg | Hypochromic normocytic or macrocytic anemia (rarely microcytic), neutropenia, thrombocytopenia, diarrhea, osteoporosis/pathologic fracturesa Intrinsic: Menkes disease18 | Chronic diarrhea, high-zinc/low-protein diets17,19 | PO: gastritis, nausea, vomiting, coma, movement/neurologic abnormalities, hepatic necrosis Intrinsic: Wilson disease | Coppers,u Ceruloplasminp |
| Iodine (I−) | 150 μg/70–140 μg (not routinely added) | Thyroid hyperplasia (goiter) + functional hypothyroidism Intrinsic in utero: cretinism, poor CNS development, hypothyroidism | Those without access to fortified salt, grain, milk, or cooking oil20 | Deficiency: causes hypothyroidism Excess: acutely causes hypothyroidism; chronic excess: hyperthyroidism | TSHs, iodineu (24-h intake and iodine: Cr ratio are more representative than a single sample) Thyroglobulins6,20 |
| Iron (Fe2+,3+) | 8 mg/1.0–1.5 μg (not routinely added) | Fatigue, hypochromic microcytic anemia, glossitis, koilonychia | Reproductive-age females, pregnant females, chronic anemias, hemoglobinopathies, post–gastric bypass/duodenectomy, alcoholics | PO or IV: hemosiderosis, followed by deposition in liver, pancreas, heart, and glands Intrinsic: hereditary hemochromatosis | Ferritins, TIBCs, % transferrin saturationc, irons |
| Manganese (Mn2+) | 2.3 mg/60–100 μg | Hypercholesterolemia, dermatitis, dementia, weight lossb | Chronic liver disease, iron-deficient populations | PO: noneb Inhalation: hallucination, Parkinsonian-type symptoms21 | No reliable markers Manganeses does not reflect bodily stores, especially in the CNS |
| Selenium | 55 μg/20–60 μg | Myalgias, cardiomyopathya Intrinsic: Keshan disease (Chinese children), Kashin–Beck disease, myxedematous endemic cretinism22 | Endemic areas of low soil content include certain parts of China and |New Zealand10 | PO: nausea, diarrhea, AMS, irritability, fatigue, peripheral neuropathy, hair loss, white splotchy nails, halitosis (garlic-like odor) | Seleniums, glutathione peroxidase activityb |
| Zinc (Zn2+) | 11 mg/2.5–5.0 mg | Poor wound healing, diarrhea (high fistula risk), dysgeusia, teratogenicity, hypogonadism, infertility, acrofacial and oral skin lesions (glossitis, alopecia), behavioral changes Intrinsic: acrodermatitis enteropathica | Chronic diarrhea, cereal-based diets, alcoholics, chronic liver disease, sickle cell, HIV, pancreatic insufficiency/any intestinal malabsorptive states, fistulas/ostomies, nephrotic syndrome, diabetes, post–gastric bypass/duodenectomy, anorexia, pregnancy19 Intrinsic: acrodermatitis enteropathica | PO: nausea, vomiting, gastritis, diarrhea, low HDL, gastric erosions Competition with GI absorption can precipitate Cu2+ deficiency Inhaled: hyperpnea, weakness, diaphoresis | Zincs,p, alkaline phosphatases (good for those on TPN, but in general Zincs,p hair, RBC, WBC levels can be misleading) Zinc radioisotope studies (most accurate tests at present; limited by cost and availability)7 |
| Vitamin A Retinol | 900 μg/3300 IU | Conjunctival xerosis, keratomalacia, follicular hyperkeratosis, night blindness, Bitot spots, corneal + retinal dysfunction | Any malabsorptive state involving proximal small bowel, vegetarians, chronic liver disease | Acute: teratogenic, skin exfoliation, intracranial hypertension, hepatocellular necrosis Chronic: alopecia, ataxia, cheilitis, dermatitis, conjunctivitis, pseudotumor cerebri, hyperlipidemia, hyperostosis | Retinols, retinol estersp, electroretinogram, liver biopsy (diagnostic for toxicity), retinol binding protein (useful in ESRD; accurately assesses blood levels)23 |
| Vitamin D Ergocalciferol | 5–15 μg/200 IU | Rickets/osteomalacia | Any malabsorptive state involving proximal small bowel, chronic liver disease Of note: those with higher skin melanin content (i.e., darker skin) have low baseline 25-OH vitamin D levels; it is unclear whether this merits their inclusion as an “at-risk” population23 | Hypercalcemia, hyperphosphatemia, which can lead to CaPO4 precipitation, systemic calcification +/− AMS +/− AKI | 25-OH vitamin Ds Of note: lively debate between IOM and Endocrine Society regarding definitions of deficiency, goal serum 25-OH levels, and at-risk populations24,25 |
| Vitamin E (α,γ)-Tocopherol | 15 mg/10 IU | Hemolytic anemia, posterior column degeneration, ophthalmoplegia, peripheral neuropathy Seen in severe malabsorption, abetalipoproteinemia | Any malabsorptive state involving proximal small bowel, chronic liver disease | Possible increased risk in hemorrhagic CVA, functional inhibition of vitamin K–mediated procoagulants | Tocopherol Must account for cholesterol/triglyceride ratio: otherwise, higher cholesterol/triglyceride ratio overestimates vitamin E, lower cholesterol/triglyceride ratio underestimates vitamin E16,c |
| Vitamin K Phylloquinone | 120 μg/150 IU | Hemorrhagic disease of newborn, coagulopathy | Any malabsorptive state involving proximal small bowel, chronic liver disease | In utero: hemolytic anemia, hyperbilirubinemia, kernicterus IV: flushing, dyspnea, hypotension (possibly related to dispersal agent) | Prothrombin timep |
| Vitamin B1 Thiamine | 1.2 mg/6 mg | Irritability, fatigue, headache Wernicke encephalopathy, Korsakoff psychosis, “wet” beriberi, “dry” beriberi | Alcoholics, severely malnourished | IV: lethargy and ataxia | RBC transketolase activityb, thiamineb,u |
| Vitamin B2 Riboflavin | 1.3 mg/3.6 mg | Cheilosis, angular stomatitis, glossitis, seborrheic dermatitis, normocytic normochromic anemia | Alcoholics, severely malnourished | Noneb | RBC glutathione reductase activityp |
| Vitamin B3 Niacin | 16 mg/40 mg | Pellagra dysesthesias, glossitis, stomatitis, vaginitis, vertigo Intrinsic: Hartnup disease | Alcoholics, malignant carcinoid syndrome, severely malnourished | Flushing, hyperglycemia, hyperuricemia, hepatocellular injuryb | N-methyl-nicotinamideu |
| Vitamin B5 Pantothenic acid | 5 mg/15 mg | Fatigue, abdominal pain, vomiting, insomnia, paresthesiasb | Alcoholics3 | PO: diarrhea | Pantothenic acidu |
| Vitamin B6 Pyridoxine | 1.3–1.7 mg/6 mg | Cheilosis, stomatitis, glossitis, irritability, depression, confusion, normochromic normocytic anemia | Alcoholics, diabetics, celiac sprue, chronic isoniazid or penicillamine use15 | Peripheral neuropathy, photosensitivity | Pyridoxal phosphatep |
| Vitamin B7 Biotin | 30 μg/60 μg | Mental status changes, myalgias, hyperesthesias, anorexiac,26 (excessive egg white consumption results in avidin-mediated biotin inactivation) | Alcoholics | Noneb,26 | Biotinp, methyl-citrateu, 3-methyl- crotonyglycineu, 3-hydroxyisovalerateu |
| Vitamin B9 Folic acid | 400 μg/600 μg | Bone marrow suppression, macrocytic megaloblastic anemia, glossitis, diarrhea Can be precipitated by sulfasalazine + phenytoin | Alcoholics, celiac or tropical sprue, chronic sulfasalazine use | PO: may lower seizure threshold in those taking anticonvulsants | Folic acids, RBC folic acidp |
| Vitamin B12 Cobalamin | 2.4 μg/5 μg | Bone marrow suppression, macrocytic megaloblastic anemia, glossitis, diarrhea, posterolateral column demyelination, AMS, depression, psychosis | Vegetarians, atrophic gastritis, pernicious anemia, celiac sprue, Crohn disease, patients postgastrectomy or ileal resection | Noneb | Cobalamin (B12)s, methylmalonic acids,p |
| Vitamin C Ascorbic acid | 90 mg/200 mg | Scurvy, ossification abnormalities Tobacco lowers plasma and WBC vitamin C13 Sudden cessation of high-dose vitamin C can precipitate scurvy | Fruit-deficient diet, smokers,13 ESRD27 | Nausea, diarrhea, increased oxalate synthesis (theoretical nephrolithiasis risk) | Ascorbic acidp, leukocyte ascorbic acid |
AKI, acute kidney injury; AMS, altered mental status; CNS, central nervous system; CVA, cerebrovascular accident; ESRD, end-stage renal disease; IOM, Institute of Medicine; GI, gastrointestinal; HDL, high-density lipoprotein (cholesterol); RBC, red blood cell; TIBC, total iron bonding capacity; TPN, total parenteral nutrition; TSH, thyroid-stimulating hormone; WBC, white blood cell.
Subscript: b, blood; c, calculated; p, plasma; s, serum; u, urine.
aOnly reported in patients on long-term TPN.
bNever demonstrated in humans.
cOnly able to induce under experimental conditions and/or only been able to induce in animals.
Special Considerations
- Both the amount and location of prior gut resection influence nutrient needs. Patients with a reduced length of functional small bowel may require additional vitamins and minerals if they are not receiving parenteral nutrition. Table 2-4 provides guidelines for supplementation in these patients.
- Ileal inflammation, resection, inflammatory bowel disease (IBD), and bypass (ileojejunal bypass) can cause B12 deficiency and bile salt loss. Diarrhea in this setting may be improved with oral cholestyramine.
- Proximal gut resection (stomach or duodenum) via partial gastrectomy, Billroth I and II, duodenal switch/biliopancreatic diversion, Roux-en-Y gastric bypass, pancreaticoduodenectomy (Whipple), and sleeve gastrectomy may impair absorption of divalent cations such as iron, calcium, and copper. Copper deficiency is extremely common in post–gastric bypass patients who do not receive routine supplementation.28
- Patients with excessive gastrointestinal (GI) tract losses require additional fluids and electrolytes. An assessment of fluid losses due to diarrhea, ostomy output, and fistula volume should be made to help determine fluid requirements. Intestinal mineral losses may be calculated by multiplying the volume of fluid loss by the fluid electrolyte concentration (Table 2-5).
- Hyperammonemic encephalopathy is an uncommon but serious complication of Roux-en-Y gastric bypass with an estimated mortality rate of 50%.29 Laboratory hallmarks include elevated ammonia, elevated plasma glutamate, hypoalbuminemia, nutritional and essential amino acid deficiencies, and low zinc.30 It does not appear to resolve with replacement of trace elements. Some reports suggest improvement with total parental nutrition after several months; however, data remain limited.31
Table 2-4: Guidelines for Vitamin and Mineral Supplementation in Patients with Severe Malabsorption
| Supplement | Dose | Route |
| Prenatal multivitamin with mineralsa | 1 tablet daily | PO |
| Vitamin Da | 50,000 units 2–3 times per week | PO |
| Calciuma | 500 mg elemental calcium tid–qid | PO |
| Vitamin B12b | 1 mg daily | PO |
| – | 100–500 μg q1–2 mo | SC |
| Vitamin Ab | 10,000–50,000 units daily | PO |
| Vitamin Kb | 5 mg/d | PO |
| – | 5–10 mg/wk | SC |
| Vitamin Eb | 30 units/d | PO |
| Magnesium gluconateb | 108–169 mg elemental magnesium qid | PO |
| Magnesium sulfateb | 290 mg elemental magnesium 1–3 times per week | IM/IV |
| Zinc gluconate or zinc sulfateb | 25 mg elemental zinc daily plus 100 mg elemental zinc per liter intestinal output | PO |
| Ferrous sulfateb | 60 mg elemental iron tid | PO |
| Iron dextranb | Daily dose based on formula or table | IV |
aRecommended routinely for all patients.
bRecommended for patients with documented nutrient deficiency or malabsorption.
Table 2-5: Electrolyte Concentrations in Gastrointestinal Fluids
| Location | Na (mEq/L) | K (mEq/L) | Cl (mEq/L) | HCO3 (mEq/L) |
| Stomach | 65 | 10 | 100 | – |
| Bile | 150 | 4 | 100 | 35 |
| Pancreas | 150 | 7 | 80 | 75 |
| Duodenum | 90 | 15 | 90 | 15 |
| Mid–small bowel | 140 | 6 | 100 | 20 |
| Terminal ileum | 140 | 8 | 60 | 70 |
| Rectum | 40 | 90 | 15 | 30 |
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Citation
Bhat, Pavat, et al., editors. "Nutrient Requirements." Washington Manual of Medical Therapeutics, 35th ed., Wolters Kluwer Health, 2016. The Washington Manual, www.unboundmedicine.com/washingtonmanual/view/Washington-Manual-of-Medical-Therapeutics/602355/all/Nutrient_Requirements.
Nutrient Requirements. In: Bhat PP, Dretler AA, Gdowski MM, et al, eds. Washington Manual of Medical Therapeutics. Wolters Kluwer Health; 2016. https://www.unboundmedicine.com/washingtonmanual/view/Washington-Manual-of-Medical-Therapeutics/602355/all/Nutrient_Requirements. Accessed February 8, 2023.
Nutrient Requirements. (2016). In Bhat, P., Dretler, A., Gdowski, M., Ramgopal, R., & Williams, D. (Eds.), Washington Manual of Medical Therapeutics (35th ed.). Wolters Kluwer Health. https://www.unboundmedicine.com/washingtonmanual/view/Washington-Manual-of-Medical-Therapeutics/602355/all/Nutrient_Requirements
Nutrient Requirements [Internet]. In: Bhat PP, Dretler AA, Gdowski MM, Ramgopal RR, Williams DD, editors. Washington Manual of Medical Therapeutics. Wolters Kluwer Health; 2016. [cited 2023 February 08]. Available from: https://www.unboundmedicine.com/washingtonmanual/view/Washington-Manual-of-Medical-Therapeutics/602355/all/Nutrient_Requirements.
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