Understanding Iron Metabolism, Hemostasis, and Blood Clotting
Iron Metabolism (Fe)
Iron is constantly lost through urine, approximately 1 mg/day. Iron consumption can be in ferrous or ferric form. Only about 10% of consumed iron is absorbed, necessitating a daily intake of 10 mg. This minimum iron intake should be doubled or tripled during pregnancy or menstruation.
Total iron reserves in the body are between 4-5 grams. 70-75% of this iron is in the form of hemoglobin, 15-20% as transferrin, 5% as myoglobin, and 1% in various other forms.
Iron is consumed in most foods, but it’s primarily absorbed in the ferrous form in the small intestine. The transformation from ferric to ferrous form occurs through:
- Hydrochloric acid (HCl)
- Bile
Iron travels through the blood via a Betaglobulina, where it’s transformed back into the ferric form for transportation. This results in Transferrin, which reaches all cells. Inside the cell, iron exists in both ferric (active) and ferrous (storage) forms.
The amount of iron in the blood is known as serum iron.
- Normal levels: Normosideremia
- Increased levels: Hipersideremia
- Decreased levels: Hypoferremia or Sideropenia
Causes of Sideropenia:
- Decreased iron intake (malnutrition): Less than 10 mg/day
- Increased iron loss (bleeding, etc.)
- Transformation problems: Bile issues
Hemostasis
Hemostasis is the body’s response to bleeding, requiring a vascular injury.
Responses to Bleeding:
1. Vascular Response:
Immediate vasoconstriction reflex. The muscular layer of blood vessels contracts involuntarily. However, blood vessels are elastic and have some resistance to injury.
2. Platelet Response:
- Tromboquinasa
- Platelet Agglutination
Tromboquinasa is a substance found in platelets that acts during bleeding. Fibrin acts on lesions.
Prothrombin + Tromboquinasa = Trobina
Fibrinogen + Thrombin = Fibrin
Platelet agglutination is the clumping of platelets at the site of injury, forming a mass that, along with fibrin, creates a clot to prevent excessive blood loss.
Requirements for Platelet Clumping:
- Blood must be in motion
- Sufficient number of platelets (minimum)
Normal platelet count: 260,000/mm3
Minimum required count: 75,000/mm3
3. Clotting Response:
The blood thickens to prevent massive blood loss. This action is triggered by clotting factors:
- Fibrinogen
- Prothrombin
- Thromboplastin
- Calcium
- Proacelerina
- Derivative of Proacelerina + Proconvertin
- Proconvertin
- Antihemophilic Factor (A)
- Antihemophilic Factor (B)
- Stuart Factor
- Antihemophilic Factor (C)
- Factor Magema
In case of bleeding, these three antihemorrhagic responses react simultaneously. For minor injuries, these responses may stop the bleeding. For serious injuries, treatment methods are required.
A fourth response, clot retraction, occurs about 2 hours after the onset of bleeding, indicating the body’s continued action against the bleeding.