Scleroderma renal crisis (SRC) is a life-threatening complication that occurs in 5 to 15 percent of systemic scleroderma patients. It is characterized by an abrupt onset of high blood pressure and acute kidney failure.

Who develops SRC?

SRC mainly occurs in patients with diffuse systemic scleroderma; it is rare in those with limited systemic scleroderma. It usually affects patients with early and rapidly progressive disease, often within four years of symptom onset. But SRC can also be a first indication of scleroderma. About 20 percent of SRC cases are reported in people not yet diagnosed and with no evidence of skin sclerosis.

Another risk factor for SRC is the presence of anti-RNA polymerase 3 antibodies in the blood. RNA polymerase 3 is an enzyme that produces RNA, a molecule chemically similar to DNA that stores genetic information. A study reviewing more than 1,000  systemic scleroderma patients reported that findings of anti-RNA polymerase 3 antibodies in the blood was associated with an increased risk of developing SRC. However, the exact link between the presence of the antibody and the development of SRC is not fully understood.

Further risk factors are palpable tendon friction rubs and synovitis (inflammation of joint-lining membranes). Another study showed that diffuse systemic scleroderma patients with palpable tendon friction rubs had more than a two-fold risk of developing SRC compared to others.

High-dose corticosteroid treatment (more than 7.5 mg daily), which is used to treat inflammation in systemic scleroderma, can also increase the risk of SRC.

SRC symptoms and diagnosis

Symptoms of SRC include acute kidney failure, a sudden onset of high blood pressure, high fever, headaches, malaise, pulmonary edema, encephalopathy, and retinopathy linked to high blood pressure. A condition known as microangiopathic hemolytic anemia (MAHA), where the red blood cells are ripped apart, can also be common, occurring in some 50 percent of SRC patients.

SRC is typically diagnosed based on findings of sudden high blood pressure and an acute increase of creatinine in the blood. Creatinine is a waste product normally removed by the kidneys. Its presence is a reliable indicator of kidney failure.

Around 10 percent of SRC patients do not have high blood pressure, makes diagnosis more difficult. In such cases and when the cause of kidney failure is not clear, a kidney biopsy may be needed to confirm an SRC diagnosis.

How is SRC treated?

SRC is considered a medical emergency and patients who are at high risk of developing the condition are recommended to closely monitor their blood pressure.

Angiotensin-converting enzyme (ACE) inhibitors are a first-line treatment for SRC. When administered at disease onset, they can be lifesaving. If they are not sufficient to control blood pressure, a calcium channel blocker and a diuretic might also be added to the treatment regimen.

Around 25 percent of SRC patients require dialysis, and kidney function is frequently restored about two years after dialysis starts. A kidney transplant is considered for patients whose kidney function does not return, and can improve quality of life.

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