Paroxysmal Nocturnal Haemoglobinuria (PNH) - Sobi

As an extremely rare autoimmune condition, PNH affects no more than a few people in every million. The symptoms of this blood disease include, but are not limited to, fatigue, brain fog, anaemia and thrombosis (blood clots).1,2

What is PNH?

PNH stands for paroxysmal nocturnal haemoglobinuria – an acquired, rare, chronic, potentially life-threatening blood disease commonly characterised by persistently low haemoglobin, thrombosis and debilitating symptoms. It occurs when the cells in the bone marrow responsible for making red blood cells (which help to carry oxygen around the body) mutate and produce defective blood cells.3 When this happens, the immune system is triggered to attack and destroy the red blood cells. The premature destruction of red blood cells is known as haemolysis. Red blood cells in a healthy individual last about 120 days before being broken down naturally in the body.4 People with PNH are subject to this premature destruction of red blood cells.5

Why is it called paroxysmal nocturnal haemoglobinuria?

The term PNH was coined in the early 20th century, based on a description of the symptoms observed in patients.

• Paroxysmal refers to symptoms occurring intermittently or suddenly.
• Nocturnal refers to the fact that it seems to occur at night (or to be observed first thing in the morning).
• Haemoglobinuria refers to haemoglobin seen in urine (discolouring it dark red or black).

The term can be misleading for some people who have PNH because, in reality, the condition is present all the time and not everyone experiences dark urine.6

How rare is PNH?

It’s difficult to derive an exact figure for how many people have PNH because the numbers are extremely small, and an unknown number of individuals may be living with the condition undiagnosed. Some estimates put the proportion of people living with PNH at between 0.5 and 2 individuals per million of the general population, although recent studies suggest that the prevalence may be somewhat higher.7,8 By any estimate, it is a very rare disease. A person can develop PNH at any age, but the median age at diagnosis is during the 30s.9 Roughly equal numbers of males and females are affected. PNH is present throughout the world and among all ethnic groups.