There are several groups where screening for PNH should be undertaken. These include patients with unexplained thrombosis who

are young, have thrombosis in an unusual site (e.g. intra-abdominal veins, cerebral veins, dermal veins), have any evidence of hemolysis (i.e. a raised LDH), or have a low red blood cell, white blood cell, or platelet count. Those who have a diagnosis of aplastic anemia should be screened annually.

The diagnosis of hemolytic anemia can be suspected on the basis of a constellation of symptoms and is largely based on the presence of anemia, an increased proportion of immature red cells (reticulocytes) and a decrease in the level of haptoglobin, a protein that binds free hemoglobin. Examination of a peripheral blood smear and some other laboratory studies can contribute to the diagnosis. Symptoms of hemolytic anemia include those that can occur in all anemias as well as the specific consequences of hemolysis. All anemias can cause fatigue, shortness of breath, decreased ability to exercise when severe. Symptoms specifically related to hemolysis include jaundice and dark colored urine due to the presence of hemoglobin (hemaglobinuria). When restricted to the morning hemaglobinuria may suggest paroxysmal nocturnal haemoglobinuria. Direct examination of blood under a microscope in a peripheral blood smear may demonstrate red blood cell fragments called schistocytes, red blood cells that look like spheres (spherocytes), and/or red blood cells missing small pieces (bite cells). An increased number of newly made red blood cells (reticulocytes) may also be a sign of bone marrow compensation for anemia. Laboratory studies commonly used to investigate hemolytic anemia include blood tests for breakdown products of red blood cells, bilirubin and lactate dehydrogenase, a test for the free hemoglobin binding protein haptoglobin, and the direct Coombs test to evaluate antibody binding to red blood cells suggesting autoimmune hemolytic anemia.

PNH is classified by the context under which it is diagnosed:

- "Classic PNH". Evidence of PNH in the absence of another bone marrow disorder.

- "PNH in the setting of another specified bone marrow disorder" such as aplastic anemia and myelodysplastic syndrome (MDS).

- "Subclinical PNH". PNH abnormalities on flow cytometry without signs of hemolysis.

The diagnosis is often made based on the medical history, blood samples, and a urine sample. The absence of urine RBCs and RBC casts microscopically despite a positive dipstick test suggests hemoglobinuria or myoglobinuria. The medical term for RBCs in the urine is hematuria.

The following findings may be present:

- Increased red cell breakdown

- Elevated serum bilirubin (unconjugated)

- Excess urinary urobilinogen

- Reduced plasma haptoglobin

- Raised serum lactic dehydrogenase (LDH)

- Hemosiderinuria

- Methemalbuminemia

- Spherocytosis

- Increased red cell production:

- Reticulocytosis

- Erythroid hyperplasia of the bone marrow

- Specific investigations

- Positive direct Coombs test

Definitive therapy depends on the cause:

- Symptomatic treatment can be given by blood transfusion, if there is marked anemia. A positive Coombs test is a relative contraindication to transfuse the patient. In cold hemolytic anemia there is advantage in transfuse warmed blood

- In severe immune-related hemolytic anemia, steroid therapy is sometimes necessary.

- In steroid resistant cases, consideration can be given to rituximab or addition of an immunosuppressant ( azathioprine, cyclophosphamide)

- Association of methylprednisolone and intravenous immunoglobulin can control hemolysis in acute severe cases

- Sometimes splenectomy can be helpful where extravascular hemolysis, or hereditary spherocytosis, is predominant (i.e., most of the red blood cells are being removed by the spleen).

Acute renal failure occurs in 55–70% of patients with STEC-HUS, although up to 70–85% recover renal function. Patients with aHUS generally have poor outcomes, with up to 50% progressing to ESRD or irreversible brain damage; as many as 25% die during the acute phase. However, with aggressive treatment, more than 90% of patients survive the acute phase of HUS, and only about 9% may develop ESRD. Roughly one-third of persons with HUS have abnormal kidney function many years later, and a few require long-term dialysis. Another 8% of persons with HUS have other lifelong complications, such as high blood pressure, seizures, blindness, paralysis, and the effects of having part of their colon removed. The overall mortality rate from HUS is 5–15%. Children and the elderly have a worse prognosis.

The similarities between HUS, aHUS, and TTP make differential diagnosis essential. All three of these systemic TMA-causing diseases are characterized by thrombocytopenia and microangiopathic hemolysis, plus one or more of the following: neurological symptoms (e.g., confusion, cerebral convulsions, seizures); renal impairment (e.g., elevated creatinine, decreased estimated glomerular filtration rate [eGFR], abnormal urinalysis); and gastrointestinal (GI) symptoms (e.g., diarrhea, nausea/vomiting, abdominal pain, gastroenteritis).The presence of diarrhea does not exclude aHUS as the cause of TMA, as 28% of patients with aHUS present with diarrhea and/or gastroenteritis. First diagnosis of aHUS is often made in the context of an initial, complement-triggering infection, and Shiga-toxin has also been implicated as a trigger that identifies patients with aHUS. Additionally, in one study, mutations of genes encoding several complement regulatory proteins were detected in 8 of 36 (22%) patients diagnosed with STEC-HUS. However, the absence of an identified complement regulatory gene mutation does not preclude aHUS as the cause of the TMA, as approximately 50% of patients with aHUS lack an identifiable mutation in complement regulatory genes.

Diagnostic work-up supports the differential diagnosis of TMA-causing diseases. A positive Shiga-toxin/EHEC test confirms a cause for STEC-HUS, and severe ADAMTS13 deficiency (i.e., ≤5% of normal ADAMTS13 levels) confirms a diagnosis of TTP.

Diagnosis is made by a positive direct Coombs test, other lab tests, and clinical examination and history. The direct Coombs test looks for antibodies attached to the surface of red blood cells.

Diagnosis is made by first ruling out other causes of hemolytic anemia, such as G6PD, thalassemia, sickle-cell disease, etc. Clinical history is also important to elucidate any underlying illness or medications that may have led to the disease.

Following this, laboratory investigations are carried out to determine the etiology of the disease. A positive DAT test has poor specificity for AIHA (having many differential diagnoses); so supplemental serological testing is required to ascertain the cause of the positive reaction. Hemolysis must also be demonstrated in the lab. The typical tests used for this are a complete blood count (CBC) with peripheral smear, bilirubin, lactate dehydrogenase (LDH) (in particular with isoenzyme 1), haptoglobin and urine hemoglobin.

The condition needs to be differentiated from pure red cell aplasia. In aplastic anemia, the patient has pancytopenia (i.e., leukopenia and thrombocytopenia) resulting in decrease of all formed elements. In contrast, pure red cell aplasia is characterized by reduction in red cells only. The diagnosis can only be confirmed on bone marrow examination. Before this procedure is undertaken, a patient will generally have had other blood tests to find diagnostic clues, including a complete blood count, renal function and electrolytes, liver enzymes, thyroid function tests, vitamin B and folic acid levels.

The following tests aid in determining differential diagnosis for aplastic anemia:

1. Bone marrow aspirate and biospy: to rule out other causes of pancytopenia (i.e. neoplastic infiltration or significant myelofibrosis).

2. History of iatrogenic exposure to cytotoxic chemotherapy: can cause transient bone marrow suppression

3. X-rays, computed tomography (CT) scans, or ultrasound imaging tests: enlarged lymph nodes (sign of lymphoma), kidneys and bones in arms and hands (abnormal in Fanconi anemia)

4. Chest X-ray: infections

5. Liver tests: liver diseases

6. Viral studies: viral infections

7. Vitamin B and folate levels: vitamin deficiency

8. Blood tests for paroxysmal nocturnal hemoglobinuria

9. Test for antibodies: immune competency

A hematologist-oncologist working in collaboration with a blood banker is helpful in complicated cases of cold agglutinin disease.

Careful planning and coordination with multiple personnel are needed if patients are to undergo a procedure during which their body temperature could fall.

Laboratory findings include severe anemia, increased mean corpuscular volume (MCV, due to the presence of a large number of reticulocytes), and hyperbilirubinemia (from increased red cell destruction) that can be of the conjugated or unconjugated type.

Cold agglutinin disease may be managed successfully using protective measures (clothing) alone in most cases. Special protective clothing is sometimes necessary in extreme cases. Therapy is directed at serious symptoms and the underlying disorder, if any is found.

Keep in mind that the idiopathic variety of cold agglutinin disease is generally a benign disorder with prolonged survival and spontaneous exacerbations and remissions in the course of the disease. Acute post infectious syndromes usually resolve spontaneously.

Anemia is generally mild. Only patients who have serious symptoms related to anemia or have a Raynaud type syndrome that constitutes a threat to life or quality of life require active therapy. The presence of an associated malignancy requires specific therapy.

Cold agglutinin disease is so uncommon in children that no specific recommendations for therapy are available. Intravenous immunoglobulin (IVIG) was used successfully in an infant with IgA-associated autoimmune hemolytic anemia.

Laboratory tests for thrombocytopenia might include full blood count, liver enzymes, kidney function, vitamin B levels, folic acid levels, erythrocyte sedimentation rate, and peripheral blood smear. If the cause for the low platelet count remains unclear, a bone marrow biopsy is usually recommended to differentiate cases of decreased platelet production from cases of peripheral platelet destruction.

Thrombocytopenia in hospitalized alcoholics may be caused by spleen enlargement, folate deficiency, and, most frequently, the direct toxic effect of alcohol on production, survival time, and function of platelets. Platelet count begins to rise after 2 to 5 days' abstinence from alcohol. The condition is generally benign, and clinically significant hemorrhage is rare.

In severe thrombocytopenia, a bone marrow study can determine the number, size and maturity of the megakaryocytes. This information may identify ineffective platelet production as the cause of thrombocytopenia and rule out a malignant disease process at the same time.

Pancytopenia usually requires a bone marrow biopsy in order to distinguish among different causes.

- anemia: hemoglobin < 13.5 g/dL (male) or 12 g/dL (female).

- leukopenia: total white cell count < 4.0 x 10/L. Decrease in all types of white blood cells (revealed by doing a differential count).

- thrombocytopenia: platelet count < 150×10/L.

Regular full blood counts are required on a regular basis to determine whether the patient is still in a state of remission.

Many patients with aplastic anemia also have clones of cells characteristic of the rare disease paroxysmal nocturnal hemoglobinuria (PNH, anemia with thrombopenia and/or thrombosis), sometimes referred to as AA/PNH. Occasionally PNH dominates over time, with the major manifestation intravascular hemolysis. The overlap of AA and PNH has been speculated to be an escape mechanism by the bone marrow against destruction by the immune system. Flow cytometry testing is performed regularly in people with previous aplastic anemia to monitor for the development of PNH.

People with PCH are sometimes advised to avoid exposure to cold temperatures. If anemia is severe, blood transfusion may be needed. Careful compatibility testing by the blood bank is necessary because autoantibodies may interfere with blood typing. Prednisone may be used in individuals with PCH and severe anemia.

There are several methods available for diagnosing and monitoring hemosiderosis including:

- Serum ferritin

- Liver biopsy

- MRI

Serum ferritin is a low cost, readily available, and minimally invasive method for assessing body iron stores. However, the major problem with using it as an indicator of hemosiderosis is that it can be elevated in a range of other medical conditions unrelated to iron levels including infection, inflammation, fever, liver disease, renal disease and cancer.

While liver biopsies provide a direct measure of liver iron concentration, the small sample size relative to the size of the liver can lead to sampling errors given the heterogeneity of iron concentration within the liver. Furthermore, the invasive nature of liver biopsy and the associated risks of complications (which can range from pain, haemorrhage, gallbladder perforation and other morbidities through to death in approx 1 in 10,000 cases) prevent it being used as a regular monitoring tool.

MRI is emerging as an alternative method for measuring liver iron loading because it is non-invasive, safer and generally cheaper to perform than liver biopsy; does not suffer from problems with sampling variability; and can be used more frequently than performing liver biopsies.

Treat the underlying cause

Blood transfusion (PRBC) according to need

In medicine, hemoglobinuria or haemoglobinuria is a condition in which the oxygen transport protein hemoglobin is found in abnormally high concentrations in the urine. The condition is often associated with any hemolytic anemia with primarily intravascular hemolysis, in which red blood cells (RBCs) are destroyed, thereby releasing free hemoglobin into the plasma. Excess hemoglobin is filtered by the kidneys, which excrete it into the urine, giving urine a purple color. Hemoglobinuria can lead to acute tubular necrosis which is an uncommon cause of a death of uni-traumatic patients recovering in the ICU .

Acute PCH tends to be transient and self-limited, particularly in children. Chronic PCH associated with syphilis resolves after the syphilis is treated with appropriate antibiotics. Chronic idiopathic PCH is usually mild.

Treatment of thrombotic thrombocytopenic purpura (TTP) is a medical emergency, since the associated hemolytic anemia and platelet activation can lead to renal failure and changes in the level of consciousness. Treatment of TTP was revolutionized in the 1980s with the application of plasmapheresis. According to the Furlan-Tsai hypothesis, this treatment works by removing antibodies against the von Willebrand factor-cleaving protease ADAMTS-13. The plasmapheresis procedure also adds active ADAMTS-13 protease proteins to the patient, restoring a normal level of von Willebrand factor multimers. Patients with persistent antibodies against ADAMTS-13 do not always manifest TTP, and these antibodies alone are not sufficient to explain how plasmapheresis treats TTP.

Treatment for hemosiderin focuses on limiting the effects of the underlying disease leading to continued deposition. In hemochromatosis, this entails frequent phlebotomy granulomatosis, immune suppression is required. Limiting blood transfusions and institution of iron chelation therapy when iron overload is detected are important when managing sickle-cell anemia and other chronic hemolytic anemias.

The treatment is antimalarial chemotherapy, intravenous fluid and sometimes supportive care such as intensive care and dialysis.