Nutritional Deficiencies and Osteoporosis
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Questions and Answers

Which of the following conditions is characterized by a deficiency in branched chain keto acid dehydrogenase?

  • Cystic Fibrosis
  • Phenylketonuria (PKU)
  • Maple Syrup Urine Disease (MSUD) (correct)
  • Homocystinuria

Which type of Maple Syrup Urine Disease is identified by severe deficiency of the enzyme?

  • Intermittent
  • Mild
  • Thiamine responsive
  • Classical (correct)

What is NOT a common sign or symptom of Maple Syrup Urine Disease?

  • Coma
  • Hyperactivity (correct)
  • Convulsions
  • Severe mental retardation (MR)

Which type of analysis is primarily used to diagnose Maple Syrup Urine Disease?

<p>Enzyme analysis of plasma and urine (A)</p> Signup and view all the answers

What dietary modification is crucial in managing Maple Syrup Urine Disease?

<p>Diet low in branched chain amino acids (BCAAs) (D)</p> Signup and view all the answers

What is a primary symptom associated with infantile scurvy?

<p>Swollen and soft gums (D)</p> Signup and view all the answers

Which vitamin is directly related to collagen hydroxylation?

<p>Vitamin C (B)</p> Signup and view all the answers

What is a consequence of a high intake of vitamin C?

<p>Formation of kidney stones (A)</p> Signup and view all the answers

Which factor negatively impacts calcium absorption in the human body?

<p>Increase in dietary fiber (A)</p> Signup and view all the answers

What is the primary source of calcium in the diet?

<p>Dairy products (D)</p> Signup and view all the answers

Postmenopausal osteoporosis is primarily linked to a decrease in which hormone?

<p>Estrogen (C)</p> Signup and view all the answers

What is the plasma calcium level range considered normal?

<p>9-11 mg/dL (C)</p> Signup and view all the answers

What is the role of vitamin D in relation to calcium?

<p>Promotes calcium absorption (B)</p> Signup and view all the answers

Which regulators primarily increase calcium levels in the plasma?

<p>PTH and Vitamin D (C)</p> Signup and view all the answers

What is the consequence of vitamin D deficiency in children?

<p>Rickets (D)</p> Signup and view all the answers

What is the primary treatment for hypocalcemia?

<p>Vitamin D supplementation (C)</p> Signup and view all the answers

In which condition is bone demineralization impaired?

<p>Marble Bone Disease (A)</p> Signup and view all the answers

What type of rickets cannot be effectively treated by increasing vitamin D intake?

<p>Renal Rickets (D)</p> Signup and view all the answers

What is the active form of vitamin D known as?

<p>Calcitriol (B)</p> Signup and view all the answers

Which process does Calcitriol NOT directly influence?

<p>Collagen synthesis (A)</p> Signup and view all the answers

What happens to 1-hydroxylase activity when plasma phosphorus levels are low?

<p>It increases (B)</p> Signup and view all the answers

What is primarily responsible for the brittle bones in Osteogenesis Imperfecta?

<p>Lack of the protein collagen (D)</p> Signup and view all the answers

Which of the following is a treatment for Osteogenesis Imperfecta?

<p>There is no cure (C)</p> Signup and view all the answers

What is the primary consequence of a deficiency in vitamin C related to collagen?

<p>Inability to form hydroxyproline (B)</p> Signup and view all the answers

In which condition is hypermobility of joints a characteristic sign?

<p>Ehlers-Danlos Syndrome (B)</p> Signup and view all the answers

What type of Ehlers-Danlos Syndrome is characterized by lethal arterial rupture?

<p>Vascular form (A)</p> Signup and view all the answers

During which age should adults over 70 years take 20mg/day of vitamin D?

<p>For optimal calcium metabolism (C)</p> Signup and view all the answers

Which of the following correctly describes the structure of collagen?

<p>Three polypeptide chains (B)</p> Signup and view all the answers

What is a common symptom of Osteogenesis Imperfecta related to posture?

<p>Kyphosis (B)</p> Signup and view all the answers

What is the primary cause of Marfan Syndrome?

<p>Mutations in fibrillin-1 protein (FBN-1) (B)</p> Signup and view all the answers

Which of the following is a major characteristic symptom of Osteomalacia?

<p>Softened and weakened bones (C)</p> Signup and view all the answers

What is the composition of the precursor tropoelastin?

<p>~700 amino acids, primarily small non-polar amino acids (C)</p> Signup and view all the answers

In which type of Mucopolysaccharidosis is the enzyme alpha-L-iduronidase deficient?

<p>Type I (Hurler syndrome) (D)</p> Signup and view all the answers

What is a key difference between osteomalacia and osteoporosis regarding age?

<p>Osteoporosis primarily affects those aged 40 and older (A)</p> Signup and view all the answers

Which of the following statements accurately describes GAGS?

<p>They can bind large amounts of water and produce a gel matrix (B)</p> Signup and view all the answers

What are the symptoms associated with the accumulation of GAGS in Mucopolysaccharidoses?

<p>Mental retardation and structural defects (B)</p> Signup and view all the answers

In the formation of desmosine, which components interact during the cross-linking of elastin?

<p>Three allysyl sides and one lysyl side (A)</p> Signup and view all the answers

Flashcards

Scurvy

A deficiency in vitamin C (ascorbic acid) leading to impaired collagen synthesis.

Infantile Scurvy (Barlow's Disease)

A severe form of scurvy impacting infants often affecting bone development and causing delayed bone growth and ossification.

L-Ascorbic Acid Pathway

The process of converting glucose to vitamin C (ascorbic acid). The body cannot produce its own vitamin C due to a lack of the enzyme L-glucono lactone oxidase.

Osteoporosis

A condition characterized by decreased bone density and increased risk of fractures.

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Post-menopausal Osteoporosis

The form of osteoporosis often seen in post-menopausal women. It's linked to the decline in estrogen levels, which play a vital role in bone health.

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Duodenum

Calcium absorption takes place primarily here. It's the first part of the small intestine.

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Calcium

Essential for bone health, muscle function, and many other vital processes.

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1,25-(OH)2 D (Serum)

The active form of vitamin D that promotes calcium absorption in the bone.

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Marfan Syndrome

A genetic disorder caused by mutations in the fibrillin-1 protein, leading to structural defects in the skeleton, eyes, and connective tissues.

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Elastin

A fibrous protein rich in proline and lysine, found in connective tissues, providing elasticity and resilience.

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Tropoelastin

The precursor to elastin, composed of ~700 amino acids, primarily small and non-polar.

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Osteomalacia

A softening and weakening of bones due to Vitamin D and calcium deficiencies, often causing pain.

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Mucopolysaccharidoses (MPS)

A group of genetic disorders resulting from the deficient breakdown of glycosaminoglycans (GAGs), leading to their accumulation in various tissues.

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Hurler Syndrome (MPS Type I)

A type of MPS, characterized by a deficiency in alpha-L-iduronidase, leading to the accumulation of heparan sulfate and dermatan sulfate.

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Hunter Syndrome (MPS Type II)

A type of MPS, characterized by a deficiency in iduronate sulfatase, leading to the accumulation of heparan sulfate and dermatan sulfate.

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Glycosaminoglycans (GAGs)

Complex, negatively charged heteropolysaccharide chains that bind with water to form a gel-like matrix in the body's ground substance.

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Calcitriol (1,25-dihydroxycholecalciferol)

The active form of vitamin D, responsible for calcium absorption in the intestines, and regulated by calcium and phosphate levels in the blood.

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Rickets

A condition in which the bones fail to mineralize properly, leading to soft and weakened bones. Often caused by insufficient vitamin D intake or a lack of sunlight exposure.

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Parathyroid hormone (PTH)

The main regulator of calcium levels in the blood, produced by the parathyroid glands. Increases calcium levels by stimulating bone resorption and reducing calcium excretion by the kidneys.

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Calcitonin

Hormone that regulates calcium levels, produced by the thyroid gland. Its action opposes PTH by lowering blood calcium levels by increasing calcium deposition in the bones and increasing calcium excretion by the kidneys.

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Hypercalcemia

A condition characterized by abnormally high levels of calcium in the blood, often caused by hyperparathyroidism. Symptoms include kidney stones, muscle weakness, and nausea.

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Hypocalcemia

A condition characterized by abnormally low levels of calcium in the blood. Often caused by hypoparathyroidism or vitamin D deficiency.

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Bone resorption

The process by which calcium is removed from the bones and released into the bloodstream. It is stimulated by PTH and inhibited by calcitonin.

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Bone deposition

The process by which calcium is deposited in the bones, building bone mass. It is stimulated by calcitonin and inhibited by PTH.

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Osteogenesis Imperfecta (Brittle Bone Disease)

A condition where bones are inadequately formed due to a lack of collagen, leading to brittle bones that break easily.

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Ehlers-Danlos Syndrome (EDS)

A group of inherited disorders affecting connective tissues, primarily collagen, leading to various symptoms like joint hypermobility and skin fragility.

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Collagen

The most abundant protein in the human body, found in connective tissues, providing structure and support.

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Why is Vitamin D Important?

Vitamin D is essential for calcium absorption, bone health, and overall well-being. A deficiency can lead to various health issues like rickets or osteomalacia.

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How Does Vitamin D Regulation Work?

The body regulates vitamin D levels through negative feedback, ensuring sufficient intake.

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Osteogenesis Imperfecta (Type II)

A condition characterized by fragile, easily fracturing bones due to a genetic defect in the collagen gene.

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Vascular Form of EDS

A form of Ehlers-Danlos Syndrome characterized by defects in collagen type III, often leading to life-threatening arterial ruptures.

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Maple Syrup Urine Disease (MSUD)

A genetic disorder caused by a deficiency in the branched chain keto acid dehydrogenase, leading to the buildup of branched chain amino acids (BCAAs) and their keto acids in the body.

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Why does urine smell like maple syrup in MSUD?

The urine of patients with Maple Syrup Urine Disease (MSUD) smells like maple syrup or burnt sugar due to the accumulation of branched chain amino acids and their keto acids.

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What are the consequences of MSUD?

The buildup of branched chain amino acids (BCAAs) and their keto acids in MSUD can lead to several complications, including severe mental retardation (MR), seizures, vomiting, acidosis, coma, and even death.

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How is MSUD diagnosed?

The diagnosis of MSUD is based on identifying elevated levels of BCAAs and their keto acids in plasma and urine. The smell of burnt sugar in the urine and a positive Rother's test are also indicative of MSUD.

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How is MSUD treated?

Treatment for MSUD involves a special diet that is low in branched chain amino acids (BCAAs) and high in thiamine. Thiamine supplements may also be prescribed.

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Study Notes

Scurvy

  • Type: Infantile Scurvy (Barlow's Disease)
  • Symptoms: Collagen synthesis problems, capillary hemorrhages, muscle weakness, bone weakness, swollen and soft gums, wound healing issues, and dental issues.
  • Cause: Deficiency of vitamin C (ascorbic acid), low intake of fresh vegetables.
  • Sources: Citrus fruits, banana, apple, tomato, onion, carrot, potato, liver, and milk.
  • Forms: Ascorbic acid, dehydroascorbic acid.

Vitamin C Functions

  • Collagen Hydroxylation: Collagen network formation, and development.
  • Iron Absorption: preventing the conversion of Fe²⁺ to Fe³⁺, thereby aiding in iron absorption.
  • Antioxidant: Protects against heart and cancer diseases.

Osteoporosis

  • Cause: Low calcium intake.
  • Postmenopausal osteoporosis: Estrogen decrease with age, leading to osteoclast activity increase, and bone loss.
  • Treatment: Increasing calcium absorption by increasing 1,25-(OH)₂D, and increasing vitamin D (active form) in the body to stimulate absorption.

Calcium Function

  • Function: Muscle contraction, bone and tissue development, blood clotting, nerve impulse transmission, enzyme activation.
  • Absorption: Absorbed in the duodenum.
  • Factors affecting absorption: Vitamin D, parathyroid hormone (PTH), low pH, lactose, and amino acids (lysine, arginine).
  • Factors affecting absorption (negative): Fatty acids and dietary fibers, high pH
  • Ca:P ratio: 1:2 or 2:1; should not exceed two times.

Hypercalcemia

  • Definition: High calcium blood level (more than 9-11 mg/dL)
  • Cause: Hyperparathyroidism (high PTH).
  • Symptoms: Stones, nausea, muscle weakness, constipation.

Hypocalcemia

  • Definition: Low calcium blood level (less than 9-11 mg/dL)
  • Cause: Hypoparathyroidism (low PTH).
  • Symptoms: Muscle spasms, convulsive seizures

Vitamin D

  • Function: Active form: 1,25-dihydroxycholecalciferol/calcitriol storage form: 25-hydroxycholecalciferol.
  • Metabolism: Skin: 7-dehydrocholesterol to cholecalciferol. Liver: converts to 25-hydroxycholecalciferol. Kidney: 25-hydroxycholecalciferol to 1,25-dihydroxycholecalciferol.

Function of Calcitriol

  • Function
  • Intestine: Binds to calcitriol receptor, produces the protein Calbindin that binds to calcium for absorption.
  • Kidney: Decreased calcium excretion.
  • Bone: Increased osteoblast activity, increases calcium absorption.
  • Sources: Fatty fish, liver, egg yolk.

Rickets

  • Cause: Deficiency of vitamin D, due to low exposure to sunlight.
  • Symptoms: Muscle weakness, joint pain, bowed legs, rachitic rosary (chest), swollen wrist and ankle joints.
  • Treatment: Vitamin D supplementation, sunlight exposure.
  • Types: Resistant/Renal Rickets: Inability of kidneys to convert vitamin D to active form.

Maple Syrup Urine Disease (MSUD)

  • Description: Urine smells like maple syrup.
  • Cause: Branched chain keto-acid dehydrogenase deficiency.
  • Symptoms: Severe mental retardation, lethargy, vomiting, coma.
  • Treatment: Diet low in branched-chain amino acids, high in thiamine (vitamin B1).

Ehlers-Danlos Syndrome (EDS)

  • Description: Connective tissue disorder.
  • Causes: Mutations in fibrillin-1 protein.
  • Symptoms: Mild bone fragility, multiple fractures, in utero fractures,kyphosis, blue sclerae, and skeletal deformities
  • Types: Vascular type and classic type
  • Defects: In collagen synthesis

Marfan Syndrome

  • Cause: Mutation in fibrillin-1 protein.
  • Symptoms: Tall stature, long extremities, flexible joints, scoliosis, aortic abnormalities, eye problems.

Mucopolysaccharidoses (MPS)

  • Description: Group of inherited metabolic disorders that involve the accumulation of glycosaminoglycans (GAGs).
  • Causes: Deficiency of enzymes needed for GAG degradation.
  • Symptoms: Mental retardation, skeletal deformities, organomegaly, and other systemic problems.

GAGs

  • Description: Large, negatively charged heteropolysaccharides.
  • Function: Component of extracellular matrix (ECM), lubrication of joints, providing flexibility to cartilage.
  • Types: Hyaluronic acid, chondroitin sulfate, keratin sulfate, heparin sulfate, dermatan sulfate.

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This quiz covers key topics related to nutritional deficiencies, specifically focusing on scurvy and the role of vitamin C. It also addresses osteoporosis, its causes, and treatments. Test your understanding of these crucial health topics.

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