Vitamins and Minerals Flashcards
(39 cards)
What type of foods are Vitamin A found?
Brightly colored vegetables, especially carrots, peppers and tomatoes, Also found in dairy, eggs, and fish. Many foods are fortified with this.
When might Vitamin A deficiency be seen?
Rare in the U.S but may be seen in patients with malabsorption, on fad diets, and the malnourished.
Key roles of Vitamin A.
Maintains healthy epithelial structure and function; operates in the visual conductive system as part of the rods and cones.
How does Vitamin A work intracellularly?
It binds to the RXR/RAR complex, which allows it to bind to nuclear targets.
This regulates cell activity and promotes various activities that help normal function of the skin, hematopoiesis, GI tract, GU system, eyes, etc.
How is Vitamin A involved in vision?
Vitamin A derivatives make up the photosensitive chemicals of the rods and cones (rods/rhodopsin, cones/iodopsin).
Upon exposure to light, these chemicals photoisomerize and send a signal down the optic nerve.
What is the most obvious symptom of Vitamin A deficiency?
Reduced integrity of epithelial tissues throughout the body. (keratosis pilaris, bronchial obstruction, Bitot spot, diarrhea, pyuria, hematuria, xerophthalmia).
Also leads to night blindness due to loss of pigment in the rods that slows adaptation to the dark. Eventually total blindness with destruction to the RPE.
What is generally the chief complaint of a patient with Vitamin A deficiency?
Typically Bitot spot, skin changes, or reduced adaptation to dark. Others may be present as well such as chronic infections.
What is the management of Vitamin D deficiency?
Vitamin D replacement
Patient/parent education.
What are the steps for management of Vitamin A deficiency?
Vitamin A supplementation and/or increased dietary intake.
Address malabsorption in present (may need higher dose of Vitamin A).
Refer to a nutritionist; other referrals may be necessary depending on symptoms.
Follow-up to check progress.
What causes hypervitaminosis A?
Excess Vitamin A ingestion for several weeks or months.
Can also be caused by certain medications (isotretinoin).
What are the signs of hypervitaminosis A?
Non-specific: headache, irritability, vomiting, diplopia, hepatomegaly, splenomegaly.
More-specific: Increased ICP, bulging fontanelles, desquamating rash (palm/soles), cheilitis, hyperostosis.
Describe the manifestation of Vitamin D dependent Rickets, Type 1 and why.
Same symptoms of Vitamin D deficiency despite the fact that the child is getting sufficient dietary Vitamin D.
Major differential diagnosis is malabsorption (calcitriol doesn’t work to convert Vitamin D).
What is the management for hypervitaminosis A?
Withdraw source of Vitamin A.
Manage hypercalcemia w/fluids, diuretics, bisphosphonates if necessary.
If inter cranial pressure is a problem, therapeutic lumbar puncture is an option.
Patient/parent education.
Follow-up to document progress.
What is Rickets?
Impairment of bone mineralization prior to epiphyseal closure which may be due to any of a host of factors. The most common being Vitamin D deficiency or receptor mutation.
Can also be calcium and phosphate deficiency.
How is Rickets manifested?
Skeletal malformations which appear as genu varum (bowleggedness) in younger children, and genu valgum (knock-knees) in older children.
Can also be manifested as skeletal (kyphoscoliosis, lumbar lordosis, rachitic rosary, greenstick fx, metaphysical cupping, craniotabes) or dental problems, muscle weakness, and Harrison’s groove.
What is the most common cause of Rickets world wide?
Vitamin D deficiency.
Primarily in developing countries where vitamin D fortified foods are not readily available.
Also see in the US in children who are on unusual diets, picky eaters, and unfortified milk (soy milk).
List the causes of Rickets.
Vitamin D related rickets: 1.) Vitamin D deficiency. 2.) Vitamin D dependent rickets, type 1. 3.) Vitamin D dependent rickets, type 2. Hypocalcemia related rickets: 1.) Renal osteomalacia 2.) Hypocalcemia rickets Hypophosphatemia related rickets: 1.) Congenital rickets (XLHR and HHRH). 2.) Other causes of hypophosphatemia.
What is the management for Vitamin D dependent Rickets, Type I?
Vitamin D replacement with calcitriol.
What are the manifestations of Vitamin D Dependent Rickets, Type 2 and why?
Same symptoms of Vitamin D deficiency (can also have alopecia) despite the fact that the child is getting sufficient dietary vitamin D. Deactivating mutation of the calcitriol receptor. Autosomal recessive disease (family hx important).
Management for Vitamin D dependent Rickets type 2 is.
Difficult to treat. Megadoses of calcitriol and calcium are used but not all children will respond.
What is renal osteomalacia?
Rickets that is superimposed on chronic kidney disease. Causes two problems: decreased production of calcitriol and impaired tubular reabsorption of calcium.
What are the manifestations of Renal osteomalacia?
Apart from signs of bone disease, the child will have a history of renal failure.
What is the management of renal osteomalacia?
Calcitriol replacement, low phosphate diet and/or phosphate binders (for anyone who has kidney disease.
When is hypocalcemia rickets manifested?
In children who are breast feeing without calcium supplementation or who are consuming unfortified formulas.
May coexist with dietary Vitamin D deficiency or malabsorption of calcium.
