Renal Involvement in Systemic Sclerosis

*Tomas Soukup, Jan Toms, Sabina Oreska, Eva Honsova and Roman Safranek*

### **Abstract**

Scleroderma renal crisis (SRC) is classical renal disease in systemic sclerosis (SSc). SRC is a relatively rare manifestation, approximately in 5% of patients. In terms of severity, manifestation in the form of SRC is the most common cause of acute organ failure. In SSc patients, SRC is defined as a new onset of accelerated arterial hypertension and rapidly progressive anuric or oliguric renal failure. SRC is primarily vascular injury with increased activity of the renin-angiotensin activity. These events lead to release or activation of cytokines and growth factors that result in the typical proliferative vascular lesions. Successful approach is routine use of angiotensin-converting enzyme inhibitors in the treatment of SRC (except prevention) and other advances in renal replacement therapy in SSc management. It is crucial to detect manifestations of SRC early and to manage appropriately in collaboration with intensive care medicine, cardiologists, and nephrologists. In contrast to SRC, clinical presentation of interstitial renal disease is poor, often without evidence of renal abnormality. Interestingly, other renal manifestations are glomerulonephritis and vasculitis. These manifestations are associated with overlapping mechanisms. The objective of this chapter is to focus on actual knowledge about the renal involvement in SSc and current treatment principles and possibilities.

**Keywords:** kidney, systemic sclerosis, scleroderma renal crisis, glomerulonephritis, diagnosis, management

### **1. Introduction**

Systemic sclerosis (SSc) leads to morbidity and mortality through a combination of inflammation, fibrosis, and vascular damage leading to internal organ complications affecting the heart, lung, bowel, and kidneys. In SSc, we observe kidney involvement as three main clinical situations described below.

Most often, SSc causes a range of renal manifestations, which occur in both subsets of the disease: limited cutaneous (lcSSc) and diffuse cutaneous (dcSSc) subsets.

As overlaps are often seen in connective tissue diseases, SSc should be associated with other immunological features of renal disease findings typical for systemic lupus erythematosus (as lupus glomerulonephritis) and ANCA-associated vasculitis/glomerulonephritis.

Scleroderma renal crisis (SRC) is a dramatic and classical scleroderma manifestation, historically known as dominant cause of scleroderma-related death. Currently, the leading causes of death in scleroderma are pulmonary fibrosis and pulmonary arterial hypertension [1]. Regardless, one-year SRC outcomes remain poor, with over 30% mortality and 25% of patients remaining dialysis-dependent.

To make the summary complete, possible drug-related adverse events including from toxic renal involvement to renal acute renal failure must be mentioned.
