The questions below were raised by visitors to the STOMP (Straits Times Online Mobile Print) website in the AskST section of the website. eMenders doctors provided the answers to the questions raised as a public health education project. The information provided below is of a general nature and should not be treated as a replacement for medical advice. You should seek consultation from a medical or healthcare professional about your specific medical condition.


In a normal healthy person, there are an estimated 5 000 000 000 000 red cells in one liter of blood. This would read 5 Trillion/L in America, and 5 Billion/L in Britain. About 7% of the body weight is blood. Thus, a 65 kg individual would have 4.55 liters of blood.

Therefore an average person weighing 65 kg would have 4.55 x 5 000 000 000 000 red blood cells, or 22.75 Trillion(American units).

It is a little more complicated with normal white blood cells. Assuming an average white blood cell count of 7000/L of blood, we should have as many as 7 000 000 000 white cells per liter of blood, or 7 billion/L. (American Billion)

However, as many as 50% of white blood cells are not circulating in the blood stream, and are marginated at the walls of blood vessels. Using the formulae above, we conclude that there are 6 360 000 000, (6.36 American Billion) circulating white cells, about twice the 3,185,000,000 estimate referred to in this question.

Contributed by Dr Ronald Ng, Haematologist.

Before answering the above question, the following factors have to be considered:

  1. How good is the lab that does the test? Does the lab regularly participate in quality control programs to verify that its results are accurate?
  2. Is there any problem with blood taking?
  3. Is the patient on any drugs, particularly anti-coagulants?
  4. Does the patient have any liver disease?

The question only reported a prolonged prothombin time that did not respond to vitamin K, with absolutely no other input regarding the cause of the prolonged prothrombin time in the first place. Without sufficient clinical data, it is rather difficult to answer this question.

However, assuming the following:

  1. That the laboratory result is accurate.
  2. That the patient is an adult with no previous history of bleeding and no previous history of prolonged prothrombin time.
  3. That the aPTT (Activated Partial Thromboplastin Time) is normal.
  4. That he or she is not on anti-coagulant.

Then, the only possible answer is that the patient has an underlying liver disease and is not responding to the Vitamin K. In such a situation, there are two options:

  1. Give Fresh Frozen Plasma to supply the missing Vitamin K dependent factor.
  2. If there is severe bleeding, the patient has to consider the use of the very expensive drug called Novo Seven.

If the person having a prolonged Prothrombin Time is a baby, there could be a possibility that the person has a congenital deficiency of one of the Vitamin K dependent factors, especially Factor X.

If the aPTT is abnormal, then one has to consider a diagnosis such as Disseminated Intravascular Coagulation where the consumption factors are consumed.

If the patient is on anti-coagulant, then one must check the dosage he/she was on. Was there an accidental overdose? If the overdose was really very high, then the amount of vitamin K that has to be given also has to be high. No dosage of vitamin K was mentioned in the question.

As the question above is a complex one, it is recommended that a haematologist be consulted for more specific medical advice.

Contributed by Dr Ronald Ng, Haematologist.