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Minerals

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plasma zinc levels act as acute phase reactants and fall by 50% with injury ... AR dz with zinc malabsorption ... TPN without zinc (diarrhea, small ... – PowerPoint PPT presentation

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Title: Minerals


1
Minerals
  • Dr Reed Berger
  • Nutrition Course Director
  • Visiting Clinical Professor GI/Nutrition

2
General Lecture Format
  • -test questions will come from clinical
    correlations--these will be relevant in clinical
    training and practice
  • -items with and those with photos are
    important!!

3
Minerals
  • A naturally occurring , homogeneous, inorganic
    substance required by humans in amts of 100
    mg/day or more
  • -functions
  • -high and low serum levels
  • -absorption
  • -excretion
  • -deficiency
  • -toxicity

4
calcium
5
Calcium
  • -most abundant mineral in the body
  • -99 of calcium is in the bones and teeth
  • -the remaining 1 is in the blood and ECF in
    cells and soft tissues

6
Skeletal Calcium
  • -if there is no reserve, calcium is drawn from
    boneleading to deficiency

7
  • Serum levels 8.8 to 10.8 mg/dl
  • when albumin is low (malnutrition, liver dz),
    calcium is decreased
  • Ratio for each gram albumin is decreased below
    4, add 0.8 to calcium

8
  • -ionized calcium is increased in acidosis and
    decreased in alkalosis (increased bicarb binds
    calcium)
  • -example in resp alkalosis, total serum
    calcium is normal, but ionized is lowalways
    check ionized level with acid/base disorders

9
Functions
  • -building and maintaining bones and teeth
  • -transport fxn of cell membranes and membrane
    stabilizer
  • -nerve transmission and regulation of
    heartbeatuse calcium gluconate IV to treat
    hyperkalemia (EKGpeaked T waves)
  • -ionized form initiates formation of the blood
    clot
  • -cofactor in conversion of prothrombin to thrombin

10
Absorption
  • -absorbed mainly in the acidic part of the
    duodenum
  • -absorption is decreased in the lower GI tract
    which is more alkaline
  • 20-30 of digested calcium is absorbed
  • Absorption is thru 1,25 (OH)2D3 (vit D
    derivative)--stimulates production of calcium
    binding protein and alk phos
  • -unabsorbed form is excreted in feces

11
Factors that increase calcium absorption
  • -more efficiently absorbed when the body is
    deficient
  • -best absorbed in acidic environment (upper
    duodenum)
  • -HCL in stomach allows better absorption in the
    proximal duodenum
  • -taking calcium with food increases abs
  • -fat increases intestinal transit time and
    increases absorption

12
Factors that decrease absorption
  • -lack of vitamin D
  • -oxalic acid forms insoluble complex which
    decreases absorption (rhubarb, spinach, chard,
    beet greens)
  • -phytic acid found in outer husks of cereal
    grains also form insoluble complex
  • -alkaline medium decreases abs.(lower GI tract)
  • Aging decreases absorption

13
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14
Maintenance of serum level
  • -parathormone (PTH) by the parathyroid gland and
    thyrocalcitonin secreted by the thyroid gland
    maintain serum levels
  • -with decreased serum calcium levels, PTH
    increases and causes transfer of calcium from
    bone to blood to increase serum levels
  • -decreased levels also cause kidney to reabsorb
    calcium more efficiently (might normally be
    excreted in the urine) and to increase intestinal
    absorption
  • -when blood levels are increased, calcitonin acts
    by the opposite mechanisms as PTH to decrease
    serum levels

15
Maintenance of serum level contd
  • -always need to correct low Mg level before
    treating a low calcium level
  • -hypomagnesemia decreases tissue responsiveness
    to PTH

16
Causes of hypocalcemia
  • -malabsorption
  • -small bowel bypass, short bowel
  • -vit D deficiency
  • -alcoholism
  • -chronic renal insufficiency
  • -diuretic therapy

17
Causes of hypocalcemia contd
  • -hypoparathyroidism
  • -hypomagnesemia
  • -sepsis
  • -pseudohypoparathyroidism
  • -calcitonin secretion with medullary carcinoma
    of the thyroid

18
Causes of hypocalcemia contd
  • -associated with low serum albumin (ionized
    calcium will be wnl)
  • -decreased end organ response to vit D
  • -hyperphosphatemia
  • -aminoglycosides, plicamycin, loop diuretics,
    foscarnet

19
Causes of hypercalcemia
  • -milk-alkali syndrome
  • -vit D or vit A excess
  • -primary hyperparathyroidism
  • -secondary hyperparathyroidism (renal insuff,
    malabsorption)
  • -acromegaly
  • -adrenal insufficiency

20
Causes of hypercalcemia contd
  • Neoplastic Disease
  • -tumors producing PTH-related proteins (ovary,
    kidney, lung)
  • -mets to bone
  • -lymphoproliferative disease including multiple
    myeloma
  • -secretion of prostaglandins and osteolytic
    factors

21
Causes of hypercalcemia contd
  • -thiazide diuretic
  • -sarcoidosis
  • -pagets disease of bone
  • -immobilization
  • -familial hypocalciuric hypercalcemia
  • -complications of renal transplant
  • -iatrogenic

22
Excretion
  • -normal is 65-70 of ingested calcium to be
    excreted in the feces and urine
  • -strenuous exercise increases loss (in sweat)
  • -immobility with bed rest and space travel
    increase calcium loss because of lack of bone
    tension

23
RDA
  • -see handout

24
sources
25
Deficiency
  • 1)boneto be discussed in osteoporosis lecture
  • 2) tetanydecreased serum levels increase the
    irritability of nerve fibers resulting in muscle
    spasms, fatal laryngospasm
  • -Chvosteks sign contraction of the facial
    m. after tapping the facial n.
  • -Trousseaus sign carpal spasm after
    occlusion of the brachial a. with blood pressure
    cuff for 3 min
  • 3) HTNcontroversial
  • 4) prolonged QT--arrythmias

26
Toxicity
  • -polyuria, constipation, bone pain, azotemia,
    coma
  • -stones, bones(bone pain), groans, psychiatric
    overtones

27
Phosphorus
  • Levels maintained by parathyroid gland

28
Functions
  • -structure of teeth and bones
  • -essential component in cell membranes, nucleic
    acids, phospholipids
  • -phosphorylation of glucose
  • -buffer system in ICF and kidney

29
absorption
  • -best occurs when calcium and phos are ingested
    in equal amts (milk)
  • -vit D also increases absorption

30
RDA
  • -see table (and for all RDAs)

31
sources
32
Sources
  • dietary sources should be restricted in renal
    disease (usually see increased phos, decreased
    Ca)
  • -protein sources
  • -meat, poultry, fish, eggs, legumes, nuts, milk,
    cereals, grains

33
Renal Disease
34
Causes of hypophosphatemia
  • -starvation
  • -TPN with inadequate phos content
  • -malabsorption, small bowel bypass
  • -vit D deficient and vit D resistant osteomalacia

35
Causes of hypophosphatemia contd
  • -phosphaturic drugs theophylline, diuretics,
    bronchodilators, corticosteroids
  • -hyperparathyoidism (primary or secondary)
  • -hyperthyroidism
  • -renal tubular defects
  • -hypokalemic nephropathy
  • -inadequately controlled DM
  • -alcoholism

36
Causes of hypophosphatemia contd
  • Intracellular shift of phosphorus
  • -administration of glucose
  • -anabolic steroids, estrogen, OCP
  • -respiratory alkalosis
  • -salicylate poisoning
  • Electrolyte abnormalities
  • -hypercalcemia
  • -hypomagnesemia
  • -metabolic alkalosis

37
Causes of hypophosphatemia contd
  • Abnormal losses followed by inadequate repletion
  • -DM with acidosiswith aggressive therapy
  • -recovery from starvation or prolonged
    catabolic staterefeeding syndrome
  • -chronic alcoholism, especially with
    nutritional repletion, assoc with
    hypomagnesemia
  • -recovery from severe burns

38
Causes of hyperphosphatemia
  • -excessive growth hormone (acromegaly)
  • -hypoparathyroidism assoc with low Ca
  • -pseudohypoparathyroidism assoc with low Ca
  • -chronic renal insufficiency
  • -acute renal failure

39
Causes of hyperphosphatemia contd
  • Catabolic states, tissue destruction
  • -stress or injury, rhabdomyolysis (esp with
    renal insufficiency)
  • -chemotherapy of malignant disease, particularly
    lymphoproliferative disease
  • Excessive intake or absorption
  • -laxatives or enemas containing phosphate
  • -hypervitaminosis D

40
Deficiency
  • -fatal
  • -usually rare with food intake
  • -respiratory muscle collapse
  • -heart failure
  • -muscle aches, bone pain, and fracture

41
Toxicity
  • -symptoms of the primary disorder

42
Magnesium
43
Function
  • -bone, muscle contractility, nerve excitability
  • -antagonistic to calcium
  • --in a muscle contraction, Mg relaxes, and
    calcium contracts
  • --low Mg can cause pregnancy induced HTN

44
Absorption / Excretion
  • -absorption varies
  • -similar to calcium (low pH, upper GI), however,
    no Vit D required-kidney conserves Mg when
    intake of Mg is low
  • -large losses with vomiting because of high
    levels of gastic juice

45
sources
46
Sources
  • -seeds, nuts, legumes, unmilled cereal grains,
    dark greens
  • -fish, meat, milk, fruits
  • -lost during refining of flour, rice, vinegar

47
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48
Causes of hypomagnesemia
  • -malabsorption, chronic diarrhea, laxative abuse
  • -prolonged GI suction
  • -small bowel bypass
  • -malnutrition
  • -alcoholism
  • -refeeding
  • -TPN with inadequate Mg

49
Causes of hypomagnesemia contd
  • -DKA
  • -diuretics
  • -hyperaldosteronism, Barrters syndrome
  • -hypercalcuria
  • -renal Mg wasting
  • -hyperparathyroidism
  • -postparathyroidectomy
  • -vit D therapy
  • -aminoglycosides, cisplatin, ampho B

50
Causes of hypermagnesemia
  • Decreased renal fxn
  • Increased intakeabuse of Mg containing
    antacids (MOM) and laxatives in renal
    insufficiency

51
Deficiency
  • -anorexia, growth failure, cardiac and
    neuromuscular changesweakness, irritability,
    mental derangement
  • -tetany, muscle cramps

52
Toxicity
  • -respiratorydepression, apnea
  • -CVhypotension, cardiac arrest, EKG (prolonged
    QRS and QT, heart block, peaked T waves)
  • -GIN/V
  • -neuromuscularparesthesias, somnolence,
    confusion, coma, hyporeflexia, paralysis, apnea

53
Iron
54
Function
  • -respiratory transport of O2 and CO2
  • -immune system
  • -cognitive performance
  • -found in Hgb (in RBCs) and myoglobin (in
    muscles)
  • -cytochrome p450 system

55
Absorption and transport
  • -dietary iron exists in heme (Hgb and myoglobin)
    and non-heme
  • -heme Fe is absorbed better
  • -non-heme Fe has to be present in the duodenum or
    upper jejunum in soluble form if it is to be
    absorbed
  • -in Fe deficiency, 50 can be absorbed
  • -2-10 of Fe from veggies is absorbed and
    10-30 is absorbed from animal protein

56
Factors affecting absorption
  • -ascorbic acid is the most potent enhancer
  • -animal proteins (beef, pork, veal, lamb, liver,
    fish, chicken) enhance
  • -but, proteins from cows milk, cheese, eggs,
    dont
  • -gastric acidity enhances absorption (antacids
    interfere)
  • -pregnancy, increased growth, Fe defic all
    increase deficiency

57
  • -phytate and tannins decrease abs
  • -Fe used for enrichment are less absorbed than
    elemental Fe
  • -increased intestinal motility decreases
    absorption because it decreases contact time for
    absorption

58
Storage
  • -stored as ferritin and hemosiderin
  • -long term high Fe ingestion or frequent blood
    transfusions can lead to accumulation of Fe in
    the liver
  • -hemosiderosis develops in individuals who
    consume a lot of Fe or have a genetic defect
    resulting in increased Fe absorption
  • -in associated with tissue damage, it is called
    hemochromatosis

59
Excretion
  • -lost thru bleeding, feces, sweat, exfoliation of
    hair and skin
  • -none in urine

60
Sources and Intakes
  • -best source is liver
  • -oysters, shellfish, kidney, lean meat, poultry,
    fish
  • -dried beans, veggies, dark molasses
  • -egg yolks, dried fruit, enriched breads,
  • -requirements are highest in infancy and
    adolescence
  • -females stay high because of menstruation
  • -decrease with menopause and increased with
    pregnancy

61
Deficiency
  • -most common deficiency
  • -most at risk lt2 yrs old, teens, pregnancy,
    elderly
  • -anemia (hypochromic, microcytic)
  • -tx diets high in absorbable Fe and/or Fe
    supplements (ferrous sulfate, ferrous gluconate)
  • -can be caused by injury, hemorrhage, illness,
    poor diet

62
Zinc
  • -involved in synthesis or degradation of CHO,
    proteins, lipids, nucleic acids
  • -stabilizes RNA and DNA
  • involved in transcription and replication
  • -needed for bone enzymes and osteoblastic activity

63
absorption
  • Impaired absorption in Crohns or pancreatic
    insufficiency
  • -plasma zinc levels act as acute phase reactants
    and fall by 50 with injury (like platelets)

64
Inhibiting Factors
  • -fiber, phytate
  • -high doses of copper
  • -Fe competes with zinc for absorption

65
Enhancing Factors
  • -glucose, lactose, and soy protein
  • -red wine
  • -human milk

66
Excretion
  • -fecesalmost entirely
  • -in urine with starvation, nephrosis, DM,
    alcoholism, hepatic cirrhosis (zinc
    supplementation in encephalopathy), porphyria

67
Sources and Intakes
  • -meat, fish, poultry, milk
  • -oysters, shellfish, meat, liver, cheese, whole
    grains, dry beans, nuts

68
Deficiency
  • -short stature, hypogonadism, anemia
  • -with diets high in unrefined cereal and
    unleavened bread
  • -delayed wound healing, alopecia
  • -acrodermatitis enteropathicaAR dz with zinc
    malabsorption
  • -eczematoid skin lesions, alopecia, diarrhea,
    bacterial and yeast infections, death

69
  • -immunologic deficitslymphopenia, thymic atrophy

70
Causes of deficiency
  • Anorexia Nervosa
  • TPN without zinc (diarrhea, small bowel fistulas)
  • High intake of phytate, tannins, binding drugs
    (EDTA), oxalate
  • High iron intake
  • Malabsorption syndromes
  • Acrodermatitis enteropathica
  • Diarrhea
  • Pancreatico-cutaneous fistula
  • Proximal entero-cutaneous fistulas
  • Hemolytic anemias (sickle cell anemia)
  • Renal failure patients on dialysis

71
Zinc Deficiency
42 yo female with chronic uremia on dialysis.
Recently started on iron supplement for anemia.
Presents with rash, hypogeusia, hyposmia and poor
dark adaptation.
72
Acrodermatitis Enteropathica
  • Autosomal recessive disease associated with a
    defect causing a reduction in zinc absorption
  • Can be treated by pharmacologic doses of oral zinc

73
Acrodermatitis Enteropathica
74
Toxicity
  • -gt100-300 mg/d
  • -rare
  • -interferes with copper absorption
  • -decrease in HDL
  • -GI irritation, vomiting

75
Fluoride
  • -tooth enamel
  • -resistance to dental caries
  • -fluoridation of h20 has decreased caries by half
  • -found in drinking h20, teflon pots and pans
    (cooked in these)
  • -toxicity at doses gt0.1 mg/kg/d

76
Prevention of dental caries
  • Incidence of dental fluorosis (mottled teeth)
    occurs with increased intake above 1-2 ppm.
  • Intervention studies have demonstrated water
    supplementation reduces prevalence of caries

77
Mottled teeth in fluorosis
78
Maganese
  • -found in many enzymes
  • -connective and bony tissue formation
  • -growth and reproduction
  • -CHO and lipid metabolism

79
Absorption and Excretion
  • -after absorption, it appears rapidly in the bile
    and is excreted in the feces
  • -concentrated in liver and increases with liver
    disease

80
Sources and Intakes
  • -whole grains, legumes, nuts, teas, fruit,
    veggies, instant coffee, and tea

81
Deficiency
  • -wt loss, ataxia, dermatitis, N/V, decreased hair
    growth, impaired reproductive activity, decreased
    pancreatic function and CHO metabolism

82
Toxicity
  • -accumulates in liver and CNSparkinsonian sx
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