ACUTE KIDNEY FAILURE

Interstitial nephritis as a cause of acute kidney failure

• Drugs

• Leptospirosis

• Hantavirus Disease
   

Hantavirus Disease

In Europe

In Europe the Puumula serotype of hantavirus produces an illness that can have many similarities to that produced by leptospirosis, although serological studies indicate that many patients must have a subclinical infection. In those that are symptomatic, high fever is typically followed within a couple of days by loin/abdominal pain and often by nausea and vomiting; photophobia and signs of meningeal irritation can also occur. Acute kidney failure follows when these symptoms have settled and is associated with conjunctival haemorrhage (20 per cent), proteinuria (almost 100 per cent of cases), microscopic haematuria (70 per cent), thrombocytopenia (50 per cent), and a transient mild rise in serum liver enzymes. There may be a small increase in serum bilirubin (maximum 40 µmol/l). Mild abnormalities of blood clotting tests are seen, but disseminated intravascular coagulation is rare.

Kidney biopsy, performed for the indication of unexplained acute kidney impairment, shows interstitial nephritis. This has no pathognomonic features, leading in this clinical context to the differential diagnosis of leptospirosis and sometimes (depending on exposure) disease induced by NSAIDs. Leptospirosis is much more likely if the serum bilirubin is markedly elevated. NSAID-induced disease does not cause conjunctival haemorrhages or thrombocytopenia. The diagnosis of Puumula hantavirus infection is made on the basis of serological evidence. Prognosis is good: no deaths have been reported and kidney function returns to normal.

In some areas of Eastern and Central Europe there is a more severe form of hantavirus infection, which is similar to that seen in Asia.

In Asia

The Hantaan and Seoul viruses cause hantavirus disease in Asia: the former causes more severe illness, but both are considerably more dangerous that the Puumula hantavirus seen in Europe. A total of five phases of disease are recognized, comprising: 

1. high fever and myalgias, followed by headache and severe abdominal/loin pain, often with an erythematous rash that may become petechial, also conjunctival haemorrhages;
2. severe hypotension;
3. gradual recovery of blood pressure, but associated with oliguria and kidney failure with proteinuria and microscopic haematuria—one-third of patients in this stage have major problems with bleeding: gastrointestinal, intracerebral or massive purpura (hence the terms epidemic or Korean haemorrhagic fever);
4. presence of polyuria;
5. convalescence.

Differential diagnosis is from severe leptospirosis and other causes of haemorrhagic fever found in Asia, including dengue and murine typhus. The diagnosis is made serologically. Treatment is supportive. Mortality is between 3 and 7 per cent; survivors recover completely.