Malnutrition

Question 0

What are two examples of protein malnutrition disorders?

Answer 0

Marasmus

Kwashiorkor

Question 1

What is the definition of malnutrition?

Answer 1

Condition resulting from diet with a lack or excess of one or more nutrients, or nutrients present in the wrong proportion

Question 2

What are the signs and symptoms of marasmus? What is the mechanism behind the disease?

Answer 2

Inadequate calorie intake (starvation) -> negative energy balance
Inadequate protein intake

Muscle wasting = lack of protein for growth/repair of muscle
therefore increased rate of muscle breakdown for gluconeogenesis/essential amino acid supply

Decrease in subcutaneous fat = lipid stores used up for energy and not replenished

• anorexia (weight loss)
• emaciated
• lethargy
• failure to thrive
• • susceptibility to infection

Question 3

What are the signs and symptoms of kwashiorkor? What is the mechanism behind the disease?

Answer 3

Poor/normal calorie intake
Inadequate protein intake -> body cannot synthesise essential amino acids

Fatty liver = few lipoproteins metabolised, therefore fat remains in liver, liver enlarges and cannot repair itself or make enzymes

Oedema = low [albumin] in blood serum due to lack of protein, fall in oncotic pressure, therefore fluid accumulates in the interstitial spaces

Lethargy = hepatic dysfunction & reduced glycolysis

Ascites = serous fluid accumulates in peritoneal cavity

• +susceptibility to infections
• anorexia (weight loss)
• failure to thrive
• hepatomegaly
• protuberant belly

Question 4

What is re-feeding syndrome? How should protein malnourished people be treated?

Answer 4

Excess protein combined with the fact that the enzymes of the urea cycle have been down-regulated leads to a build-up of ammonia (hyperammonaemia) which causes death by causing irreversible damage to the CNS.

Protein should be re-introduced slowly to allow up-regulation of the urea cycle enzymes, allowing ammonia to be detoxified by the liver. Vitamin/mineral/essential amino acid supplements should be supplied.

Question 5

What is Starling’s law of capillaries?

Answer 5

Fluid movement due to filtration between the blood vessels and surrounding interstitial fluid is dependent on the balance between the hydrostatic and oncotic pressure gradients across the capillary walls.

Arterial end = BP > OP
Venous end = BP < OP

Question 6

What is the mechanism of oedema? What are some other clinical consequences of oedema?

Answer 6

Low serum albumin ——> reduced oncotic pressure in capillaries
——-> leaking of fluid from capillaries to interstitial spaces

Causes hepatomegaly & ascites