Minerals (1.16) Flashcards
What is the most abundant mineral in the body?
Calcium
What functions does calcium serve?
Bone mineralization Blood clotting Muscle contraction Metabolism regulator Secondary messenger
What regulates calcium absorption?
PTH –> Vitamin D (calcitriol) –> tsl of proteins
Calcineurin –> inhibits calcium channels
Calcium/calmodulin kinase –> Inhibits glycogen synthase
What increases calcium absorption?
Vitamin D
Sugar/Sugar alcohols
Protein
What decreases calcium absorption?
Fiber
Phytic, oxalic acids
Other divalent cations
Unabsorbed fatty acids
How does calcium usually travel in the blood? What is the second most likely form?
Calcium is mostly in free ionized form in the blood
Significant amount also travels bound to protein (albumin)
What effect does calcium have on phosphorus and iron uptake?
Calcium blocks phosphorus and iron uptake
What does calcium do to fatty acids and bile salts?
Calcium traps fatty acids and bile salts in a non-digestible soap
How is calcium excreted?
Urine
Feces
Sweat
What controls calcium reabsorption in the proximal tubule? What can effect calcium reabsorption?
Calcitriol controls calcium reabsorption
Caffeine increases calcium excretion
Increased sodium increases calcium excretion
Who is at risk for calcium deficiency?
Patients with fat malabsorption disorders Immobilized patients (bone calcium stores deplete)
What can calcium deficiency cause?
Rickets
Tetany
Osteoporosis
What is calcium deficiency associated with?
Colorectal cancer
HTN
DMII
What is the best method of determining if a patient has calcium deficiency?
Bone density scan
What are the symptoms of acute calcium toxicity?
Constipation
Bloating
What are the symptoms of chronic calcium toxicity?
Calcification of soft tissue
Hyperaclciuria
Kidney stones
What is the second most abundant mineral in the body?
Phosphorus
Where is the majority of the phosphorus in the body?
Bone
How is phosphorus usually absorbed? What form is phosphorus in?
Diffusion in proximal duodenum
H2PO4-
How can phosphorus be absorbed if intake is low?
Calcitriol activates a saturable carrier mediated active transporter
What inhibits phosphorus absorption? What does this mean for treating hyperphosphatemia?
Magnesium
Aluminum
Calcium
Antacids can be used to treat hyperphosphatemia from kidney failure
What functions does phosphorus serve?
Bone mineralization
High energy bonds
Acid/base tolerance
Availability of oxygen (2,3-BPG)
What promotes phosphorus excretion?
Elevated dietary phosphorus
PTH
Acidosis
Phosphotonins–from osteoblasts and osteocytes
What inhibits excretion of phosphorus?
Low dietary phosphorus Calcitriol Alkalosis Estrogen Thyroid hormone Growth hormone
What are some external causes of phosphorus deficiency?
Extreme antacid use
Malnourishment
Refeeding syndrome
What are some inherited disorders that cause phosphorus deficiency?
Dents Disease
X-linked Hypophosphatemic Rickets
Autosomal dominant Hypophosphatemic Rickets
What is Dents Disease?
X-linked
Mutation in renal Chloride channel
What is X-linked Hypophosphatemic Rickets?
Mutation of PHEX gene –> elevated FGF-23
What is Autosomal dominant Hypophosphatemic Rickets?
Mutation in the gene encoding FGF-23 gene…prevents its degradation
What are the symptoms of phosphorus deficiency?
Anorexia Reduced cardiac output Decreased diaphragmatic contractility Myopathy Death
What is the third most abundant mineral in the body?
Potassium
How is potassium absorbed?
Paracellular diffusion
K/H ATPase
Basolateral K+ channel
What functions do potassium serve?
Electrical membrane potential
Muscle contractility
How is potassium regulated?
Vasopressin and aldosterone increase urinary K+ excretion…opposite of Na+
What does potassium do to calcium excretion?
K+ decreases Ca++ excretion…opposite of Na+
What are some functions of chloride?
Chloride/Bicarb exchanger (RBC, intestinal, etc.) Hypochlorous acid (secreted by neutrophils during phagocytosis to neutralize pathogens)
What can cause chloride deficiency?
Fluid loss
Thiazide or loop diuretics
Refeeding syndrome
What are the symptoms of potassium deficiency?
Cardiac arrhythmias Muscle weakness Hypercalciuria Glucose intolerance Mental disorientation
What happens with moderate potassium deficiency?
Elevated blood pressure
Decreased bone density (increased urinary calcium excretion)
What can cause hyperkalemia? What can hyperkalemia cause?
Renal failure can lead to hyperkalemia
Hyperkalemia can lead to cardiac arrhythmia/arrest
What foods have magnesium?
Nuts Legumes Whole grains Chlorophyll Chocolate 'Hard' water
How is magnesium transported into the blood?
Through a magnesium channel (TRPM6)
Out a Mg/Na ATPase
What form of magnesium is highest in the blood?
Free –> protein bound –> salt
What are some interactions magnesium has on other dietary substances?
Mimics calcium –> competes for reabsorption in the kidney
Inhibits phosphorus absorption by forming a precipitate
What is the best measurement of magnesium level?
Renal Mg excretion before and after a loading dose
Erythrocyte magnesium isn’t a horrible measure
What are some causes of magnesium deficiency?
Gitelman Syndrome
What is Gitelman Syndrome?
Autosomal recessive mutation –> thiazide sensitive Na/Cl
Besides hypomagnesemia, what else does Gitelman Syndrome cause?
Hypokalemia
Hypocalciuria
What are the symptoms of magnesium toxicity?
Diarrhea Dehydration Flushing Slurred speech Muscle weakness Loss of deep tendon reflex Cardiac arrest...[Mg] > 15mg/dL
What is associated with magnesium toxicity?
Epsom salt
How does iron enter the intestinal epithelium?
Fe(3+) –reductase–>Fe(2+)
Fe(2+) –DMT1–> into cell
How does iron leave the intestinal cell?
Fe(2+) –ceruloplasmin–>Fe(3+)
Fe(3+) –ferroportin–> plasma (transferritin)
What are the functions of iron?
Heme synthesis
Iron-sulfur clusters (electron transfer group)
Dioxygenase
What are some interactions iron has with other dietary stuffs?
Vitamin C enhances absorption and maintains iron in reduced state
Copper (required for ceruloplasmin)
Iron inhibits zinc absorption
Who occasionally has iron deficiency?
Infants (low iron diets)
Adolescents (rapid growth rate)
Pregnant (rapid growth rate; blood loss at delivery)
Absorption disorders
What are the symptoms of iron deficiency?
Microcytic hypochromic anemia
Listlessness
Fatigue
What foods have copper?
Meat
Shellfish
Nuts
How is copper transported to the blood?
Cu(2+) –reductase–> Cu(+)
Cu(+) –CTR1–> enterocyte
Enterocyte –ATP7A–> blood (bound to proteins)
What is a mutation that effects copper transport?
Menkes kinky hair syndrome
What is seen with Menkes kinky hair syndrome?
Hypothermia Hypotonia Poor feeding Failure to thrive Seizures Normal hair at birth --> becomes brittle/sparse
What are the functions of copper?
Cofactor for ceruloplasmin
Cytochrome C oxidase has 3 Cu+/enzyme
Cofactor for lysyl oxidase (collagen synthesis…also requires ascorbate)
Superoxide dismutase (antioxidant enzyme)
Dopamine beta-hydroxylase (catecholamine synthesis)
What causes copper deficiency?
Too much zinc
A lot of PPIs
What are the symptoms of copper deficiency?
Anemia
Leukopenia
Hypopigmentation of skin/hair
Altered cholesterol metabolism
What are the acute symptoms of copper toxicity?
Epigastric pain
N/V
Diarrhea
What are the chronic symptoms of copper toxicity?
Hematuria
Liver damage
Kidney damage
What is Wilson Disease?
Mutation in liver specific copper transporter ATP7A
What is the effect of Wilson Disease?
Cannot transport excess copper into bile –> copper accumulates
What can be seen in the eyes of a person with Wilson Disease?
Kayser-Fleischer ring
What are the treatment options for Wilson Disease?
Avoid high copper foods
Chelation therapy
