PNH has about the same frequency in men and women, and it is encountered in all populations throughout the world, but it is a rare disease: its prevalence is 1–5 per million (it may be somewhat less rare in Southeast Asia and in the Far East). There is no evidence of inherited susceptibility. PNH has never been reported as a congenital disease, but it can present in small children or in people in their seventies, although most patients are young adults. Clinical Features The patient may seek medical attention because one morning she or he has passed "blood instead of urine.". | Chapter 101. Hemolytic Anemias and Anemia Due to Acute Blood Loss Part 16 PNH has about the same frequency in men and women and it is encountered in all populations throughout the world but it is a rare disease its prevalence is 1-5 per million it may be somewhat less rare in Southeast Asia and in the Far East . There is no evidence of inherited susceptibility. PNH has never been reported as a congenital disease but it can present in small children or in people in their seventies although most patients are young adults. Clinical Features The patient may seek medical attention because one morning she or he has passed blood instead of urine. This distressing event may be regarded as the classical presentation however more frequently this symptom is not noticed or is suppressed. Indeed the patient often presents simply as a problem in the differential diagnosis of anemia whether symptomatic or discovered incidentally. Sometimes the anemia is associated from the outset with neutropenia or thrombocytopenia or both. Some patients may present with recurrent attacks of severe abdominal pain defying a specific diagnosis and eventually found to be caused by thrombosis. When thrombosis affects the hepatic veins it may produce acute hepatomegaly and ascites . a full-fledged Budd-Chiari syndrome which in the absence of liver disease ought to raise the suspicion of PNH. The natural history of PNH can extend over decades. Without treatment the median survival is 8-10 years in the past the commonest cause of death has been venous thrombosis followed by infection secondary to severe neutropenia and hemorrhage secondary to severe thrombocytopenia. PNH may evolve into aplastic anemia AA and PNH may manifest itself in patients who previously had AA. Rarely estimated 1-2 of all cases PNH may terminate in acute myeloid leukemia. On the other hand full spontaneous recovery from PNH has been well documented albeit rarely. Laboratory Investigations and Diagnosis The most consistent .
