Diagnosis and Treatment of Nutritional Deficiencies

Questions and Answers

What was the primary finding in the muscle biopsy of the patient?

Hyperplasia of muscle tissue

Increased muscle fibers

Lipid deposition (correct)

Infiltration of immune cells

Which of the following is a consequence of low carnitine levels?

Enhanced use of long-chain fatty acids

Inability to utilize long-chain fatty acids (correct)

Increased energy metabolism from carbohydrates

Improved lipid metabolism

What condition indicates a diagnosis of carnitine deficiency?

High plasma levels of carnitine

Increased carnitine synthesis

Below normal carnitine levels (correct)

Elevated free fatty acid levels

Which treatment was initiated for the patient diagnosed with carnitine deficiency?

Daily dose of L-carnitine Signup and view all the answers

What improvements were noted within 1 month of starting treatment?

Increased physical activity Signup and view all the answers

What type of fatty acids accumulate due to the impaired utilization from low carnitine levels?

Toxic amounts of free fatty acids Signup and view all the answers

What is a genetic defect related to carnitine deficiency?

Congenital absence of carnitine acyltransferase Signup and view all the answers

What is typically observed in plasma levels of carnitine in affected individuals?

Below normal carnitine levels Signup and view all the answers

What indicates a failure in carnitine synthesis?

Defective carnitine synthesis Signup and view all the answers

What are the characteristics of Methylmalonic Acidemia in relation to enzyme defects?

It results from an inability to convert vitamin B12 to its coenzyme form. Signup and view all the answers

Which statement correctly describes the oxidation of unsaturated fatty acids?

They produce fewer reducing equivalents due to their reduced state. Signup and view all the answers

Which type of pathway is ω-oxidation considered in fatty acid metabolism?

A minor pathway generally significant for certain tissues. Signup and view all the answers

What effect does a deficiency in the mutase enzyme have on fatty acid metabolism?

Can lead to developmental retardation. Signup and view all the answers

When referring to naturally occurring fatty acids, what is true about their double bonds?

The double bonds are mainly in the cis configuration. Signup and view all the answers

Which of the following accurately describes the characteristics of propionate and methylmalonate in urine?

They are excreted during instances of metabolic dysfunction. Signup and view all the answers

What is the main implication of developmental retardation in Methylmalonic Acidemia?

It results from unprocessed metabolic intermediates. Signup and view all the answers

Which enzyme is specifically involved in shifting the double bond in monounsaturated fatty acids during oxidation?

Δ3-cis-Δ2-Trans Enoyl CoA Isomerase Signup and view all the answers

Which of the following is a consequence of the incomplete oxidation of fatty acids?

Elevated levels of toxic metabolic intermediates. Signup and view all the answers

What is a physiological characteristic of the acetone produced in untreated diabetes mellitus?

It contributes to metabolic acidosis during ketoacidosis. Signup and view all the answers

Which of the following best describes the relationship between ketonemia and ketonuria?

Ketonuria accompanies high ketonemia levels. Signup and view all the answers

What odorous characteristic can be observed in untreated diabetic patients?

A fruity scent due to elevated acetone levels. Signup and view all the answers

Why is excessive ketone body production particularly dangerous in untreated diabetic patients?

It can result in life-threatening ketoacidosis. Signup and view all the answers

What role do peripheral tissues play in the utilization of ketone bodies during ketosis?

They utilize ketone bodies only in the absence of glucose. Signup and view all the answers

What happens to acetoacetate in untreated diabetic patients?

It often accumulates in high concentrations in the blood. Signup and view all the answers

What is one potential cause of carnitine deficiency in newborns?

Inadequate biosynthesis Signup and view all the answers

Which of the following is a sign of carnitine deficiency?

Episodic hypoglycemia Signup and view all the answers

How does hemodialysis contribute to carnitine deficiency?

Through renal leakage Signup and view all the answers

What is one physiological effect of eicosanoids?

They elicit a wide range of physiologic responses Signup and view all the answers

What symptom can result from lipid accumulation due to carnitine deficiency?

Muscular weakness Signup and view all the answers

What type of treatment is recommended for carnitine deficiency?

Oral carnitine supplementation Signup and view all the answers

Which of the following statements about prostaglandins is true?

They are metabolized to inactive products locally. Signup and view all the answers

In carnitine deficiency, what happens to plasma free fatty acids?

They accumulate as a result of impaired fatty acid oxidation. Signup and view all the answers

What is the role of eicosanoids in the body?

They elicit specific physiologic responses. Signup and view all the answers

Why is carnitine not stored to any appreciable extent in the body?

It is metabolized quickly and not retained. Signup and view all the answers

What condition is characterized by the abnormal build-up of phytanic acid leading to vision loss and a loss of smell?

Zellweger’s Syndrome Signup and view all the answers

Which of the following fatty acids are typically accumulated in the brain due to peroxisomal dysfunction in Zollweger’s Syndrome?

C26-C38 polyenoic acids Signup and view all the answers

Which pharmacological category does NOT affect the synthesis of leukotrienes?

NSAIDs Signup and view all the answers

What kind of inhibitor is Aspirin classified as regarding prostaglandin synthesis?

Irreversible inhibitor Signup and view all the answers

Which of the following is NOT a consequence of defective peroxisomal function?

Synthesis of leukotrienes Signup and view all the answers

What role does phospholipase A2 play in the context of cell signaling?

Synthesizes arachidonic acid from membrane phospholipids Signup and view all the answers

Which of the following statements about NSAIDs is accurate?

They prevent the synthesis of parent prostaglandins. Signup and view all the answers

Which of the following represents a potential outcome of Zellweger's Syndrome?

Developmental delays Signup and view all the answers

What is the main reason for the accumulation of phytanic acid in Zellweger's Syndrome?

Inhibition of peroxisomal enzymes Signup and view all the answers

Which of the following accurately describes the consequences of a lack of peroxisomes?

Impaired lipid metabolism and accumulation of fatty acids Signup and view all the answers

Study Notes

Diagnosis and Treatment of Carnitine Deficiency

Signs of muscle weakness and lipid deposition observed in skeletal muscles.
Diagnosis confirmed by below normal levels of carnitine in muscle biopsy and plasma.
Genetic defects include:
- Congenital absence of carnitine acyltransferase.
- Defective carnitine synthesis leading to low carnitine concentration.
Consequence of deficiency:
- Inability to utilize long-chain fatty acids as a metabolic fuel.
- Accumulation of toxic free fatty acids and branched-chain acyl groups in cells.
Treatment initiated with daily administration of 174 mg/kg L-carnitine.
Improvement seen within a month: increased activity and decreased irritability.

Vitamin B12 Deficiency

Methylmalonic acidemia and aciduria can arise from:
- Inability to synthesize vitamin B12 coenzyme or mutations in mutase.
Symptoms may include metabolic acidosis and developmental retardation.
Propionate and methylmalonate detected in urine as byproducts.

Fatty Acid Oxidation

Unsaturated fatty acids make up 50% of body fatty acids; they yield less energy due to lower reduction state.
Oxidation primarily occurs through the β-oxidation pathway, aided by specific enzymes.
Natural fatty acids predominantly contain cis double bonds; β-oxidation addresses trans configurations via isomerization.

Alternative Pathways for Fatty Acid Oxidation

ω-oxidation involves oxidation of terminal methyl groups forming ω-hydroxy fatty acids; a minor pathway.
Carnitine deficiency more prevalent in newborns, notable in preterm cases due to insufficient synthesis or renal leakage.

Eicosanoids such as thromboxanes and leukotrienes are potent compounds with diverse physiological impacts, produced in trace amounts across tissues.
Prostaglandins are not stored and have short half-lives; they play critical roles in local signaling.

Synthesis and Regulation of Prostaglandins

Cortisol inhibits phospholipase A2, reducing availability of arachidonic acid for prostaglandin synthesis.
NSAIDs, including aspirin and phenylbutazone:
- Aspirin is an irreversible inhibitor of prostaglandin synthesis.
- Other drugs provide reversible inhibition of synthesis.

Zellweger Syndrome

Rare inherited condition characterized by absence of peroxisomes, leading to accumulation of polyenoic acids in brain tissue.
Results in severe defects due to impaired oxidation of long-chain fatty acids.

Ketonemia and Ketonuria

Acetone is a nonmetabolizable byproduct of ketone body metabolism; can be detected in breath of untreated diabetic patients.
High levels of ketone bodies lead to diabetic ketoacidosis; characterized by fruity breath odor and high production of ketones.
Ketonuria (presence of ketones in urine) aligns with ketonemia during ketosis.

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Description

This quiz covers the diagnosis and treatment of carnitine and vitamin B12 deficiencies. It includes symptoms, genetic defects, and the metabolic consequences associated with these deficiencies. Test your understanding of the clinical approaches to managing these conditions.