Calculate the deficit for a 60 kg person,with Hb – 5 g/dl add 1000 mg for iron stores.
**Core Concept**
Total body iron is approximately 3-4 grams in adults, with 2.7 grams stored in the liver, spleen, and bone marrow. The total iron content can be calculated using the formula: total iron (in mg) = body weight (in kg) x 3.5 mg/g.
**Why the Correct Answer is Right**
To calculate the deficit, we need to determine the total body iron content and subtract the stored iron content. Assuming a normal body weight of 60 kg, the total body iron content is 60 kg x 3.5 mg/g = 210 mg/kg x 60 kg = 12,600 mg. Since 1 gram of iron is equivalent to 500 mg, the total body iron content is 12,600 mg / 500 mg/g = 25.2 g. Adding 1000 mg for iron stores, we get 25.2 g x 500 mg/g + 1000 mg = 12,600 mg + 1000 mg = 13,600 mg. The normal hemoglobin (Hb) is approximately 15 g/dl, and the deficit can be calculated as: (15 g/dl - 5 g/dl) x 3.0 ml/g x 60 kg = (10 g/dl) x 3.0 ml/g x 60 kg = 1800 ml or 1800 g. Since 1 g of Hb contains 3.4 mg of iron, the iron deficit is 1800 g x 3.4 mg/g = 6120 mg. Now, the total iron deficit is the sum of the iron deficit from Hb and the iron stores, which is 6120 mg + 1000 mg = 7120 mg. Converting this to grams, we get 7120 mg / 500 mg/g = 14.24 g. However, since the question asks for the deficit in a 60 kg person, we need to calculate the deficit per kg of body weight. The total body iron content is 12,600 mg, and the iron deficit is 7120 mg. The deficit per kg of body weight is (7120 mg / 60 kg) x 100% = 11.87%.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not take into account the total body iron content and the iron stores.
* **Option B:** This option is incorrect because it does not calculate the deficit per kg of body weight.
* **Option C:** This option is incorrect because it does not add 1000 mg for iron stores.
* **Option D:** This option is incorrect because it does not subtract the iron deficit from the total body iron content.
**Clinical Pearl / High-Yield Fact**
When calculating the iron deficit, it's essential to consider both the iron deficit from Hb and the iron stores. This can be done by calculating the total body iron content and subtracting the stored iron content.
**Correct Answer: C. 11.87%**