Paroxysmal nocturnal haemoglobinuria - PNH for short - is an uncommon blood disorder. It is not primarily a malignant condition [but is often diagnosed in laboratories which specialise in haematological malignancies]. In PNH the red blood cells are weak and are thus destroyed more rapidly than normal. This causes the urine to turn red or dark during an episode (or paroxysm) of red cell destruction (or haemolysis). Usually the urine is darker first thing in the morning (nocturnal) and clears through the day. Each episode of dark urine usually lasts for a few days and attacks may occur very occasionally or very often. During an attack of dark urine many patients have mild abdominal discomfort. If the pain is severe then patients should contact their Haematologist. Many patients are unable to swallow food or even liquid when an attack is at it's most severe. This usually passes off quite quickly. Some patients with PNH never have attacks of dark urine.
The increased destruction of red cells usually causes some degree of anaemia (low haemoglobin). In most patients the body is able to adjust quite well to the anaemia because it's onset is usually gradual. Patients with PNH should take the vitamin folic acid each day because the body needs folic acid to help replace the destroyed red cells. Some patients also need to take iron tablets. Occasionally, if the anaemia becomes severe, blood transfusion may be necessary.
PNH occurs because one of the cells in the bone marrow (where blood is made) has undergone a change (or mutation). The blood cells that are made by this bone marrow cell are abnormal (or PNH). This change only affects a proportion of blood cells and therefore the patient almost always has a proportion of normal cells. By using sophisticated machines we can accurately measure the proportion of PNH cells in the blood and this is how PNH is diagnosed [flow cytometry]. Analysis of the proportion of PNH cells gives some indication of how an individual patient will be affected by their PNH.
PNH can occur in men or women or, very rarely, in children. It can occur at any age. PNH is not an inherited condition (there is no increased risk in family members) and PNH cannot be passed from one person to another.
One of the major complications in PNH is the development of blood clots (thrombosis) in the veins. This occurs in just under half of patients with PNH. Some patients are treated with tablets to thin the blood (warfarin) to prevent blood clots occurring. Whether warfarin is recommended for a patient depends on his or her individual risk of developing clots and the risk of warfarin therapy in the individual.
In some patients PNH develops after a previous diagnosis of aplastic anaemia (a weak bone marrow). In a small proportion of patients the marrow may become weaker after PNH is diagnosed. This can result in a low white cell count which renders the patient prone to infections that must be treated promptly with appropriate antibiotics. In addition the platelet count may fall to low levels resulting in an increased risk of excessive bruising/bleeding which may require treatment with platelet transfusions. Patients developing a weak bone marrow may require specific treatment to improve their blood counts.
The course of PNH is very variable. In most cases PNH goes on for many years and the patient gets used to living with the disease. Many patients with PNH lead an active life with as little disruption as possible caused by their PNH. However complications can arise and regular follow-up in a Haematology clinic is necessary. Some patients are more severely affected by their PNH and may need more intensive treatment.
At the moment the only treatment which can cure PNH is bone marrow transplantation (BMT). BMT can only be performed in a minority of patients who have suitable family members (usually brothers or sisters) who may have the same tissue type. There is only a one in four chance that a full brother or sister will be a match. In addition there is a significant risk associated with BMT and this risk increases with age. Therefore BMT cannot be recommended for the majority of patients with PNH and even in those patients with potential donors a BMT may not be advised unless the patient has experienced certain complications or is very severely affected by their PNH. It is likely that recent advances in the way BMT is performed may make transplantation much safer and therefore increase the number of patients who can be treated in this way.
Patients (male and female) with PNH are usually fertile. There is however an increased risk of complications during pregnancy so that it is important that the decision to get pregnant is only made after detailed discussion with the patient's doctor. The risks of pregnancy can be reduced (but probably not to normal levels) by careful monitoring and treatment during the pregnancy. It is not advisable for women with PNH to use the oral contraceptive pill as these all appear to increase the risk of thrombosis. Chronic diseases such as PNH can have an affect on a patient's sex drive (libido). Occasionally young men with PNH have problems with maintaining erections and there are now effective therapies which can help such problems.
A significant proportion of patients with PNH will eventually get better by themselves with all their PNH cells disappearing from the blood leaving an essentially normal blood count. This spontaneous cure can occur even in the most severely affected patients and usually occurs several years after the diagnosis of PNH is made. Repeating the tests for PNH (flow cytometry) may help to identify patients who are likely to have a spontaneous cure and currently we advise that these are repeated at least every year.
Since PNH is an uncommon disease most patients with the disease may never have heard of it before they are diagnosed and would never meet another patient with PNH. Several patients have suggested that it would be helpful to make contact with or even meet other patients with PNH. If you wish to make contact with other patients there is a PNH Message Board here at the HMDS website. To protect the confidentiality of contributors, this area is currently password-protected (under review) and access requires registration.
Alternatively if you do not have regular access to the internet then you can write to, or e-mail, the following address and we will attempt to put you in touch with other patients:
Comments & feedback to: admin@hmds.org.uk