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GI > Pyruvate Kinase Deficiency > Flashcards

Pyruvate Kinase Deficiency Flashcards

1
Q

A subtype of anemia which results in increased destruction of erythrocytes

A

Hemolytic Anemia

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2
Q

Hemolytic anemia is coupled with an increase in RBC production because there is a decreased oxygen carrying capacity with loss of functional red blood cells which triggers

A

Erythropoetin (EPO) Production

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3
Q

Refers defects in the erythrocytes themselves

A

Intrinsic hemolysis

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4
Q

These are often hereditary and include the hemoglobinopathies, membrane deficiencies such as hereditary spherocytosis and elliptocytosis, enzyme deficiencies, and paroxysmal nocturnal hemoglobinuria.

A

Intrinsic hemolysis

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5
Q

Refers to factors outside of the red blood cell that cause hemolysis

A

Extrinsic hemolysis

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6
Q

These are almost always acquired and include causes such as infections, toxins, hypersplenism, microangiopathic hemolysis, liver disease and autoimmune hemolytic anemia

A

Extrinsic hemolysis

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7
Q

The features of extravascular hemolysis are

A

Anemia, splenomegaly, and jaundice

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8
Q

In hemolytic anemia, erythrocytes are most often

A

Normochromic and normocytic (MCV 80-100)

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9
Q

In G6PD deficiency, the shape of RBCs is described as

A

Heinz bodies

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10
Q

Helmet cells signifying destruction

A

Schisocytes

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11
Q

An enzyme that catalyzes the last reaction of the glycolytic pathway

A

PYruvate Kinase

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12
Q

Catalyzes the transfer of the high-­energy phosphate bond from phosphoenolpyruvate (PEP) to ADP in an irreversible step producing ATP and pyruvate

A

PYruvate kinase (PK)

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13
Q

In mammals, there are four

A

PK isoforms

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14
Q

Encodes PKL, expressed in the liver and some cells of the pancreas, intestine, and kidney

A

PKLR gene

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15
Q

Also encodes PKR expressed in erythrocytes

A

PKLR gene

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16
Q

Encodes PKM1 and PKM2 through alternative splicing

A

PKM gene

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17
Q

Clinical PK deficiency with hemolytic anemia is limited to mutations of the

A

LR gene

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18
Q

In affected individuals, activity of erythrocytic PK is

-Whereas PK activity in white cells, platelets, and
other tissues is normal

A

Markedly reduced

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19
Q

Devoid of a nucleus, mitochondria, ribosomes, and other organelles and thus has no capacity for cell replication, protein synthesis, or oxidative phosphorylation

A

Mature eryhtrocytes

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20
Q

The glycolytic production of ATP is the only source of energy production for the

A

Mature RBC

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21
Q

A deficiency in the functionality of pyruvate kinase causes decreased production of

A

ATP

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22
Q

Low ATP levels are responsible for erythrocyte concentration disruption, due to failure of the energy driven

A

Na+/K+ ATPase

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23
Q

A consequence of this is cellular distortion, rigidity, and dehydration which leads to premature erythrocyte destruction driven mostly by the

A

Spleen and liver

24
Q

Additionally, the conversion of glucose to glucose-­6-

phosphate requires

A

ATP

25
Q

An intermediate of the hexose monophosphate pathway and the de-­novo glutathione synthesis from glycine, glutamate, and cysteine

A

G-6-P

26
Q

Made from HMP and glutathione are essential in protecting the erythrocyte against free radical production

A

NADPH

27
Q

Therefore pyruvate kinase deficiency leaves RBCs susceptible to intracellular

A

Oxidative stress

28
Q

An autosomal recessive disorder with an estimated prevalence of 1 In 300,000 live births

A

Pyruvate Kinase Deficiency

29
Q

Affects both genders equally and occurs in all races with highest incidences occuring in the Amish population and internationally in Northern Europe and Japan

A

PKD

30
Q

Which mutations are common in European patients with PK deficiency?

A

G1529 → A and the C1456 → T

31
Q

Which mutation is common in Japanese patients with PK deficiency?

A

C1151 → T

32
Q

Individuals affected by PKD are either homozygous for a single mutation

A

Compound heterozygous (2 different mutations)

33
Q

Have intermediate enzyme levels that usually do not produce clinical disease

A

PKD heterozygotes

34
Q

Can be acquired as a result of blood disorders such as leukemia, preleukemia, and refractory sideroblastic anemia

A

PKD

35
Q

Since RBCs lack mitochondria, the conversion of pyruvate to lactate regenerates

A

NAD+ from NADH

36
Q

The only method of ATP generation in RBCs

A

Glycolysis

37
Q

Physiologically, the hemoglobin of affected individuals has an increased capacity to release oxygen into the tissues due to a stalling at the level of pyruvate kinase causing

A

PEP accumulation

38
Q

PEP is converted back to 3-phosphoglycerate, leading to increased

A

2,3-BPG

39
Q

Interestingly, for a comparative hemoglobin and hematocrit level individuals with PKD have more efficient

A

Oxygen delivery

40
Q

Individuals with PKD are more resistant to

A

P. Falciparum

41
Q

The clinical severity of this disorder varies and can range from

A

Mile compensated anemia to severe anemia

42
Q

Variable clinical severity is explained, at least in part, by the existence of numerous mutant forms of the enzyme whose differing properties result in variable degrees of

A

Hemolysis

43
Q

Symptoms include jaundice, icteric sclera, and hepatosplenomegaly due to hemolysis

A

Severe PK Deficiency

44
Q

Can also result due to increased levels of bilirubin (byproduct of erythrocyte destruction) in the biliary ducts

A

Pigmented Gallstones

45
Q

Fatigue and lethargy are common in PKDs due to impaired oxygen delivery given decreased amounts of

A

RBCs

46
Q

In very severe cases of PKDs, heart failure can result from extensive anemia in newborns-­-­ this is called

A

Hydrops Fatalis

47
Q

One thing to workout when you suspect PKD is

A

LDH (Lactate Dehydrogenase)

48
Q

Decreased haptoglobin levels are a marker for

A

Intravascular Hemolysis

49
Q

Bilirubin is the byproduct of the breakdown of red blood cells. Increased bilirubin levels signify

A

Hemolysis

50
Q

Young erythrocytes that are produced by the bone marrow in times of increased red blood cell destruction

A

Reticulocytes

51
Q

High levels of reticulocytes signify

A

Hemolytic Anemia

52
Q

NADH fluorescence under ultraviolet light is a commonly used screening test for

A

PK Deficiency

53
Q

Loss of fluorescence of NADH under ultraviolet light in this test is observed as evidence of the presence of

A

PKD

54
Q

Show echinocytes (RBC with thorny projections) which have deformed shapes due to the disrupted cell membrane that occurs because of lack of energy requirements to run the Na/K ATPase pump

A

Peripheral Blood Smear

55
Q

What is the treatment for PKD?

A

Transfusions and Vitamin supplementation (folic acid and B Vitamins)

56
Q

Only indicated in severe cases due to increased risk of serious bacterial infections

A

Splenectomy

GI (59 decks)

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