Heme/Iron Metabolism Test Questions

Question 1

What happens when you give Isoniazid – what vitamin do you need to supplement?

Answer 1

Isonazid (TB treatment) can cause B6 deficiency resulting in peripheral neurophaty, CNS effects and anemia
B6

Question 2

What happens in bilirubin in hemolysis – what component is elevated?

Answer 2

Patient with hemolysis – high indirect fraction. liberation of unconjugated bilirubin (Indirect) into serum, will be high. Direct/conjugated should be normal.

Question 3

What happens with bilirubin in obstruction-cholestasis?

Answer 3

Patient with obstruction – high direction fraction. Conjugated bilirubin high, meaning that it has been to liver where conjugation occurs. Then a block in the bile duct or a tumor in the pancreatic head.

Question 4

Characteristics of porphyria cutanea tarda?

Answer 4

Deficiency of hepatic uroporphyrinogen decarboxylase

Hepatitis/HFE Hemochromatosis, estrogens

Bullous dermatosis, scarring, hyperpigmentation, hypertrichosis

Elevated urine total porphyrins

Question 5

5060 yo w iron deficiency anemia, what tests to order

Answer 5

endoscopy and colonoscopy (right sided colon cancers)

swallow a camera

Question 6

What happens in anemia chronic disease?

Answer 6

Hypoproliferative anemia secondary to inflammation, iron stores increased but decrease in utilization (Iron is there, just cannot get out of cells)
Increase in Hepcidin (which destroys more ferroportin → iron cannot leave cells)
Associated with chronic nonhematologic conditions (TB, endocarditis, AIDS, malignancy, RA, SLE, trauma)
EPO – hormone by kidney, needed to make heme. Deficient.
low serum iron (not bioavailable)
low serum transferrin concentration/TIBC
normal to elevated serum ferritin concentration

Question 7

How to treat hematochromatosis

Answer 7

• Phlebotomy

* May want to biopsy liver to see how much damage done, if catch before damage and treat – > normal life expectancy.

Question 8

Labs for iron deficient anemia

Answer 8

Low serum iron, low serum ferritin (less than 20, often less than 10 → if so, IDA for sure), increase in TIBC
Reduced MCV – usually sits at 80-100, less than 80 in these cases (microcytic anemia)

Question 9

Labs for chronic disease anemia

Answer 9

Low serum iron (no ferroportin), normal/high serum ferritin (body senses iron in the cell), Transferrin sat reduced – iron not there in serum so TIBC low

Question 10

Labs for hemochromatosis

Answer 10

serum iron high, serum ferritin high, serum transferrin high, TBC low (decreasing transferrin because the iron is high)
In a ddx: see that transferrin and ferritin are both high, then C282Y/C282Y study

Question 11

Explain C282Y

Answer 11

Situations with high iron – induction of hepcidin. Destroys ferropotin so iron stays sequestered in cells and cannot enter serum. Sloughed off eventually
HFE is a transmembrane protein (MHC I class) expressed in liver.
Regulates hepcidin expression
• Mutation results in lack of expression, no generation of hepcidin in context of high iron.
• Therefore all Iron is bioavailable and in serum.

Question 12

Why heme iron is absorbed better than no-heme iron?

Answer 12

Heme > non
Proximal bowel (duodenum), enhanced by gastric acid
• Stomach acid converts Fe 3+ (ferric) to Fe 2+ (ferrous) → better absorbed, also conversion in brush boarder. Important because DMT1 only recognizes Fe 2+
• Promotors: ascorbic acid, citric acid, spices, b-carotene, alcohol → OJ with iron supp.
• Inhibitors: phytic acid, polyphenols, tannins, calcium