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Why does my blood come out so slowly?

Dr Shirish Kumar
Haematologist,
WHO,
Geneva

Q: I am 30 years old. Recently, I donated blood and while donating it, I noticed that the blood was coming out very slowly. The doctors too noticed this. Why is this so? My haemoglobin count is 14. A few days back I was diagnosed with Meralgia Paraesthetica. Are these two related? My cholesterol level is normal and I am not diabetic. Kindly tell me why this has happened, and what do I do to solve this problem?

A:Meralgia paraesthetica is a disorder causing pain in the front and outer part of the thigh due to the entrapment of the lateral femoral cutaneous nerve as it passes through the inguinal ligament. This may result from obesity, tight clothing or injury to the nerve or growths in that region. This will in no way affect the flow of blood as that depends on the viscosity of blood.Viscosity is a property of fluids that is related to the internal friction within the layers of a flowing fluid and also the friction between the fluid and the wall of the vessel in which it is flowing. The viscosity of plasma (the fluid part of the blood) is due to the presence of proteins in it and blood is nearly 4 times more viscous than water at 37°C (the normal body temperature). This depends on the haematocrit (proportion of cells in blood), temperature, and flow rate. An increase in haematocrit (due to an increase in red blood cells or decrease in the fluid part of the blood), a decrease in temperature or a decrease in the rate of flow of blood in a vessel can all markedly increase the viscosity of blood. You need to discuss this with your doctor who can examine you and then explain this to you.