Scleroderma renal crisis is often the most challenging type of scleroderma emergency to identify promptly, according to Francesco Boin, MD, professor of medicine and director of the scleroderma center at the University of California, San Francisco.
“Fortunately, it’s not a frequent event. But it’s severe enough that all rheumatologists should be aware of it,” he said at the virtual edition of the American College of Rheumatology’s 2020 State-of-the-Art Clinical Symposium.
Atypical presentations occur in 30%
Scleroderma renal crisis (SRC) occurs in 5%-10% of scleroderma patients. A vexing feature of this emergency is that not uncommonly it actually precedes the diagnosis of scleroderma. Indeed, 20% of patients with SRC present with sine scleroderma – that is, they have no skin disease and their renal crisis is their first symptom of scleroderma. In contrast, critical digital ischemia – the most common scleroderma emergency – is invariably preceded by worsening episodes of Raynaud’s, and impending intestinal pseudo-obstruction – also among the most common scleroderma emergencies – is heralded by an established history of dysmotility, loss of appetite, abdominal bloating, small intestinal bacterial overgrowth, and bowel distension.
While sine SRC often poses a formidable diagnostic challenge, SRC occurs most often in patients with early, rapidly progressing diffuse scleroderma skin disease. Indeed, the median duration of scleroderma when SRC strikes is just 8 months. The use of glucocorticoids at 15 mg or more per day, or at lower doses for a lengthy period, is an independent risk factor for SRC. Detection of anti–RNA polymerase III antibodies warrants increased vigilance, since 60% of patients with SRC are anti–RNA polymerase III antibody positive. Other autoantibodies are not a risk factor. Neither is preexisting hypertension nor a high baseline serum creatinine.
The classic textbook presentation of SRC is abrupt onset of blood pressures greater than 20 mm Hg above normal for that individual, along with sudden renal failure; a climbing creatinine; proteinuria; and expressions of malignant hypertension such as pulmonary edema, new-onset heart failure, encephalopathy, and/or development of a thrombotic microangiopathy.
Notably, however, 30% of individuals with SRC don’t fit this picture at all. They may present with abrupt-onset severe hypertension but no evidence of renal failure, at least early on. Or they may have sudden renal failure without a hypertensive crisis. Alternatively, they may have no signs of malignant hypertension, just an asymptomatic pericardial effusion or mild arrhythmias.
“Also, the thrombotic microangiopathy can be present without the other features of scleroderma renal crisis, so no renal failure or hypertensive emergency. Be aware of the possibility of atypical presentations, and always suspect this unfolding problem in the right individuals,” the rheumatologist urged.
Anyone with scleroderma who presents with new-onset hypertension needs to begin keeping a careful home blood pressure diary. If the blood pressure shoots up, or symptoms of malignant hypertension develop, or laboratory monitoring reveals evidence of thrombotic microangiopathy, the patient should immediately go to the ED because these events are often followed by accelerated progression to renal crisis.
Inpatient management of SRC is critical. “In the hospital we can monitor renal function in a more refined way, we can manage the malignant hypertension, and early on, hospitalization provides the opportunity to do a renal biopsy. I always consider doing this early. The pathologist often pushes back, but I think it’s relevant. It confirms the diagnosis. We’ve had patients where we were surprised: We thought it was scleroderma renal crisis, but instead they had interstitial nephritis or glomerulonephritis. Most important, biopsy has major prognostic implications: You can measure the extent of damage and therefore have a sense of whether the patient will be able to recover renal function,” Dr. Boin explained.
Prognosis and predictors
Outcome of SRC is often poor: the 1-year mortality is 20%-30%, with a 5-year mortality of 30%-50%. Normotensive SRC with renal crisis, which accounts for about 10% of all cases of SRC, is particularly serious in its implication, with a 1-year mortality of 60%. Half of patients with SRC require hemodialysis, and only one-quarter of them recover spontaneous renal function.
Predictors of worse outcome include older age at onset of SRC, male gender, a serum creatinine level above 3 mg/dL at presentation, incomplete blood pressure control within the first 3 days of the crisis, and normotensive SRC. Use of an ACE inhibitor prior to SRC is also an independent predictor of poor outcome, possibly because by keeping the blood pressure under control the medication blunts recognition of the unfolding renal crisis.
“This is why experts don’t recommend prophylactic ACE inhibitors in patients who are at risk for SRC,” according to Dr. Boin.
He reported having no financial conflicts regarding his presentation.