Biochemistry-Vitamins & Minerals Flashcards
One of a group of organic substances, present in minute amounts in natural foods that are essential to normal metabolism
Vitamins. Compounds that we cannot synthesize on our own or cannot make enough that we require.
Absorption of what vitamins is dependent on the ileum and bile emulsification? What vitamins wash out easily from the body?
Fat soluble vitamins: A, D, E, K. Water soluble vitamins: B1,2,3,5,6,7,12, C and folate.
What vitamins cause toxicity more often?
Fat soluble (A,D,E,K) because they can accumulate in fat
Deficiency in what vitamins often results in dermatitis, glossitis and diarrhea?
B-complex deficiencies
Vitamin deficiency associated with poor vision? Osteoporosis? Increased ROS? Poor clotting? Collagen synthesis? Neural tubes? Peripheral neuropathy?
Vision: A. Osteoporosis: D. ROS: C,E. Clotting: K. Collagen: C. Neural tube: folate. Neuropathy: B12.
What things can cause deficiency in the vitamin that is a coenzyme in the cleavage of C-C bonds in amino acid and carbohydrate metabolism?
B1 (Thiamine) activated is thiamine pyrophosphate. Alcoholism, chronic diuretic use and hyperemesis can cause B1 deficiency.
A patient presents with symmetrical tingling and pain in both hands and peripheral edema. A few months later she is brought to the ED with severe heart failure. What is causing her condition? How do you test to confirm your diagnosis? How do you treat her?
She is exhibiting symptoms of B1 (thiamine) deficiency. Polyneuropathy = dry beriberi. Cardiomegaly = wet beriberi. Confabulations = Wernicke-Korsakoff syndrome. Picture show ophthalmoplegia. Adding B1 to transketolase and observing 25% increase in activity = thiamine deficiency. You treat her by giving IV B1 PRIOR to giving glucose to prevent lactic acidosis.
Most common CNS-related neurological problem in alcoholics
Wernicke-Korsakoff syndrome from B1 deficiency.
What things can cause deficiency in the vitamin that is a cofactor for oxidation and reduction reactions, and is often covalently attached to some enzymes?
B2 (riboflavin). Deficiency can be caused by photodegradation and other B vitamin deficiencies (doesn’t typically show up on its own).
A patient presents with a magenta tongue (glossitis), angular chelitis (inflamed corners of mouth) and corneal vascularization. These symptoms are hallmarks of what vitamin deficiency?
B2 (riboflavin)
Why is milk best packaged in cardboard? Why is your pee yellow after taking a vitamin?
Cardboard: prevent photodegradation of riboflavin. Yellow pee: color of riboflavin.
What things can cause deficiency in the vitamin that is a coenzyme for oxidation and reduction reactions, and is not covalently bound to enzymes?
B3 (niacin). Alcoholism, B2, B6 and Trp (some niacin comes from trp and requires B2 & B6 for conversion) deficiencies, Hartnup disease (decreased trp absorption), carcinoid syndrome (increased trop metabolism) and isoniazid (decreased B6)
A patient presents with a pigmented rash on sun-exposed areas, bright red tongue, diarrhea, apathy, memory loss and disorientation. She only really eats corn products. What is causing her condition?
She is presenting with symptoms of pellagra: dermatitis, diarrhea, dementia and death. Corn is low in tryptophan and causes B3 deficiency (niacin).
What toxicity might you see in a patient who takes niacin for hyperlipidemia?
Facial flushing.
What things can cause deficiency in the vitamin that is a cofactor for many many enzymes of amino acid metabolism?
B6, activated form is PLP. Deficiency can be caused by alcoholism and isoniazid.
A patient presents with seborrhea, glossitis, convulsions, neuropathy, depression, confusion and labs show microcytic anemia. What vitamin deficiency are these clinical symptoms consistent with?
B6 deficiency (microcytic anemia because it is needed for ALAS in heme biosynthesis)
What things can cause deficiency in the vitamin that is used in many carboxylation reactions?
B7 (biotin) deficiency is very rare. It is sometimes seen on people on parenteral nutrition after surgery that only eat egg whites. In infants B7 deficiency presents due to AR biotinidase defects that prevents action on biocytin to activate biotin.
What things can cause deficiency in the vitamin that is a coenzyme for one-carbon transfer in nucleic acid and amino acid metabolism?
Folic acid deficiency is caused by alcoholism, methotrexate, increased demand during pregnancy, low SES, elderly and malabsorption (Crohn’s/celiac)
What things can cause deficiency in the vitamin that is a coenzyme for methionine synthase and methylmalonyl CoA mutase?
B12 deficiency can be caused by gastric atrophy (pernicious anemia), terminal ileal disease, gastric surgery, veganism and acid-reducing drugs (H2 blockers, PPIs).
A patient presents with petechiae, ecchymosis, coiled hairs, poor wound healing, fatigue and inflamed and bleeding gums. Ultrasonography of his painful knee reveals a joint effusion. What is causing his condition?
Vitamin C deficiency. Inability to hydroxylate proline residues causes weak collagen.
A patient presents with xerophthalmia (dry eyes), night blindness, Bitot’s spots, follicular hyperkeratosis, impaired embryonic development and immune dysfunction. Supplementation of this vitamin deficient patient will help prevent what types of cancer?
Squamous cell cancer can be prevented by vitamin A supplementation. Also, you can treat AML t(15;17) with ATRA to “fix” the broken retinoic acid receptor.
2 patients come to your office, one child has rachitic rosary (rib knobs) and bowed leg, the adult has osteomalacia. What organs may be dysfunctional that are causing these symptoms?
The kid has rickets and the adult is presenting with vitamin D deficiency. The liver is responsible for vit D3 conversion to 25-OH-D. The kidney is responsible for conversion to 1,25(OH)2D (calcitriol), which is the active hormone.
What does 1,25(OH)2D do? Why does absence of this cause rickets?
PTH stimulates renal production of 1,25(OH)2D by increasing 1-OHase. 1,25(OH)2D then stimulates Ca/P absorption in the intestine, increases renal Ca retention and increases bone osteoclast activity. When 1,25(OH)2D is absent, PTH stimulates demineralization of bone without deposition induced by vitamin D.
