Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Analytes > iron > Flashcards

iron Flashcards

1
Q

What is the Fenton reaction?

A

Ferrous iron plus hydrogen peroxide produces damaging, highly reactive hydroxyl radicals plus ferric iron

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the two storage forms of iron?

A

Ferritin and haemosiderin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Main site of absorption of iron

A

Duodenum and proximal jejunum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Main storage site of surplus iron

A

Hepatocytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Most iron in the body is found in…

A

Erythrocytes and macrophages

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Main role of hepcidin

A

Regulator of iron absorption and macrophage iron release

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Where is hepcidin synthesized?

A

Hepatocytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

In what forms does hepcidin circulate?

A

Free, and bound to alpha-2 macroglobulin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is ferroportin?

A

The main exporter of iron from within cells to the blood stream

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How does hepcidin regulate iron release/absorption?

A

By binding to ferroportin, which causes its internalisation and degradation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Where is ferroportin found?

A

On the basolateral surface of jejunal enterocytes and on macrophages

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the role of hephaestin and ceruloplasmin in iron metabolism?

A

They are multicopper oxidases that catalyse the oxidation of Fe 2+ to Fe 3+ for loading onto transferrin. Hephaestin does this from enterocytes and ceruloplasmin does this from macrophages and hepatocytes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

The erythroid progenitor cells uptakes which form of iron:
a) hepcidin bound
b) ferroportin bound
c) transferrin bound
d) hephaestin bound

A

c) transferrin bound

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Where does heme synthesis occur?

A

In the mitochondria of the erythroid progenitor cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How many subtypes of hereditary haemochromatosis are there?

A

6

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the classical hereditary haemochromatosis phenotype? How many of the subtypes have this classical phenotype?

A

Normal Hb
Increased ferritin and transferrin saturation
Tissue iron overload
5/6 of the subtypes have this classical phenotype

17
Q

What is the most common genotype for hereditary haemochromatosis?

A

Homozygous C282Y (cysteine to tyrosine at position 282) mutation of the HFE gene on chromosome 6

18
Q

Briefly describe the pathogenesis of hereditary haemochromatosis.

A

Insufficient hepcidin cause increased ferroportin causes excessive iron absorption which exceeds the needs of the body. Deposition of Fe in parenchymal organs eg liver and pancreas

19
Q

Benefits of early diagnosis and therapy for hereditary haemochromatosis

A

Prevent the development of tissue damage
Reduce morbidity and mortality
Provide long-term survival similar to the general population
Improve mental wellbeing

20
Q

Therapy for hereditary haemochromatosis

A

Phlebotomy - 1 unit (500mL) blood/week until serum ferritin 50-100 ug/L

21
Q

How is therapeutic phlebotomy for hereditary haemochromatosis monitored?

A

Measure serum ferritin every 10-12 phlebotomies (approx 3 monthly) until target of 50-100 ug/L is reached. May need to monitor more closely when approaching target to ensure iron deficiency does not develop.

22
Q

Carrier frequency of HFE gene mutation?

A

1 in 10

23
Q

Prevalence of hereditary haemochromatosis (HFE gene C282Y homozygotes) in a Caucasian population?

A

1 in 200

24
Q

Second most common mutation of HFE gene after C282Y? What kind of disease is this gene mutation associated with?

A

H63D (his63asp). H63D homozygotes and C282Y/H63D compound heterozygotes are not considered disease-associated genotypes and rarely get clinically significant iron overload

25
Q

In which proteins do mutations cause hereditary haemochromatosis?

A

Hepcidin
Ferroportin
Haemojuvelin
Transferrin receptor

26
Q

What are the 6 subtypes of hereditary haemochromatosis and what genes are affected?

A

HH type 1 - HFE
HH type 2A - HAMP
HH type 2B - HJV
HH type 4 - TfR2
HH type 4A - SLC40A1 (LOF)
HH type 4B - SLC40A1 (GOF)

27
Q

What is “ferroportin disease”

A

HH type 4A - SLC40A1 LOF results in iron overload restricted to reticuloendothelial system. Patients have high ferritin, normal transferrin saturations and, rarely, iron-restricted erythropoiesis with mild anaemia and intolerance of phlebotomy. Patients rarely develop iron-related disease symptoms. A diagnosis of exclusion (of other causes of hyperferritinaemia)

28
Q

Causes of hyperferritinaemia

A
  1. Infection/inflammation
  2. Metabolic syndrome
  3. Renal insufficiency
  4. Malignancy
  5. Familial hyperferritinaemia-congenital cataract syndrome
  6. Aceruloplasminaemia
  7. Ferroportin disease
29
Q

How is hereditary haemochromatosis diagnosed?

A

After identification of a patient with the typical biochemical pattern (increased ferritin and increased transferrin saturation), genetic testing, usually firstly of the HFE gene for the most common C282Y mutation eg by Sanger sequencing, followed by more extensive screening eg by next generation sequencing, if an HFE mutation is not found.

30
Q

Typical pattern of laboratory investigations for hereditary haemochromatosis

A

Iron - high
Ferritin - >300 ug/L (M), >200 ug/L (F)
TF sats - >45%
Hb, MCV and MCH - high-normal

31
Q

What does the HFE gene code for?

A

The HFE protein - this protein modulates the expression of hepcidin.

32
Q

How does obesity cause iron deficiency?

A

Low-grade inflammation increases hepcidin production which reduces iron absorption and release from the reticuloendothelial system.

33
Q

Causes of a high transferrin sats

A

Haemochromatosis
Recent oral iron supplement ingestion

34
Q

Causes of an absurdly high ferritin (100000+)

A

Severe, acute liver failure
Haemophagocytic lymphohistiocytosis
Malignancy
HH
Adult onset Still’s disease
Juvenile arthritis
Chronically transfused states eg sickle cell

35
Q

Your lab’s iron method

A

Iron released from transferrin under acidic conditions, which simultaneously reduces ferric iron to ferrous form. Ferrous iron complexes with ferrozine to produce a chromogen which absorbs at 57/658

36
Q

Your lab’s transferrin method

A

Immunoturbidimetric

37
Q

Transferrin sats calculation

A

Iron/TF × 1.2

38
Q

Your lab’s ferritin method

A

Two site chemiluminescent immunoassay

Analytes (15 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions