Scleroderma and kidney damage

Systemic scleroderma is a polysyndrome autoimmune disease characterized by progressive fibrosis and widespread vascular pathology by the type of obliterating microangiopathy underlying the generalized Raynaud's syndrome, skin and internal organs (lung, heart, digestive tract, kidney).

[1], [2], [3], [4], [5]

Epidemiology

The incidence of systemic scleroderma averages 1 case per 100 000 population. Recently, there has been an increase in the incidence of systemic scleroderma, which is associated with both a true increase in the incidence and with improved diagnosis. Scleroderma rarely develops in childhood, with age its frequency increases. The most common disease is diagnosed at the age of 30-50 years. Women suffer on average 4 times more often than men, and in childbearing age - 15 times.

[6], [7], [8], [9], [10], [11], [12]

Pathogenesis

Scleroderma nephropathy is a vascular pathology of the kidneys caused by the occlusive lesion of the intrarenal vessels, resulting in organ ischemia and manifested arterial hypertension and impaired renal function of varying severity.

There are two forms of kidney damage in systemic scleroderma - acute and chronic.

• Acute scleroderma nephropathy (syn. - true scleroderma kidney, scleroderma kidney crisis) -  acute renal failure, developed in patients with systemic scleroderma in the absence of other causes of nephropathy and occurring in most cases with severe, sometimes malignant arterial hypertension.
• Chronic scleroderma nephropathy is a low-symptom pathology, which is based on a reduction in renal blood flow with a subsequent decrease in GFR. In the early stages of the disease, this is established by the clearance of endogenous creatinine (Reberg's test) or isotope methods. As a rule, the reduction in GFR is combined with minimal or moderate proteinuria, often with hypertension and initial signs of chronic renal failure.

[13], [14], [15], [16], [17], [18], [19], [20]

Symptoms of the systemic scleroderma

The defeat of the kidneys in systemic scleroderma most often develops in patients with diffuse cutaneous form of the disease, with acute progressive course of the disease, at a period of 2 to 5 years from the beginning, although nephropathy can develop and with a chronic slowly progressing course of scleroderma. The main symptoms of scleroderma nephropathy are  proteinuria, arterial hypertension and impaired renal function.

• Proteinuria is typical for most patients with systemic scleroderma with kidney damage. As a rule, it does not exceed 1 g / day, is not accompanied by changes in urinary sediment, and in 50% of patients it is combined with arterial hypertension and / or renal dysfunction. Nephrotic syndrome develops extremely rarely.

True scleroderma kidney

The true scleroderma kidney is the most severe manifestation of scleroderma nephropathy. It develops in 10-15% of patients with systemic scleroderma, usually in the first 5 years from the onset of the disease, more often in the cold season. The main risk factor for its development is a diffuse cutaneous form of scleroderma with progressive course (rapid progression of skin lesions within several months). Additional risk factors - elderly and senile age, male gender, belonging to the Negroid race. They are also unfavorable for the prognosis of acute scleroderma nephropathy.

Diagnostics of the systemic scleroderma

In a laboratory study, patients with systemic scleroderma can detect anemia, moderate increase in ESR, leukocytosis or leukopenia, hyperproteinemia with hypergammaglobulinemia, elevated levels of C-reactive protein and fibrinogen.

Immunological studies show an antinuclear factor (in 80% of patients), a rheumatoid factor (mainly in patients with Sjogren's syndrome) and specific antinuclear "scleroderma" antibodies.

These include:

• antitopizomeraznye (formerly called aHTH-Scl-70), detected primarily in diffuse cutaneous form of systemic scleroderma;
• anticenteric - in 70-80% of patients with a limited form of systemic scleroderma;
• anti-RNA polymerase - associated with high incidence of kidney damage.

[21], [22], [23], [24], [25]

Treatment of the systemic scleroderma

With malosimptomnom lesion of the kidney, noted in the majority of patients with systemic scleroderma, in the case of normal arterial pressure, special treatment can be avoided. The development of moderate arterial hypertension serves as an indication for the onset of antihypertensive therapy. The drugs of choice are ACE inhibitors that suppress the plasma renin activity increased in scleroderma nephropathy.

It is possible to prescribe any drugs of this group in doses that ensure normalization of blood pressure. In case of side effects (cough, cytopenia) with the use of ACE inhibitors, beta-blockers, slow calcium channel blockers, mainly in retard forms, alpha-adrenoblockers, diuretics in various combinations should be prescribed.

Forecast

The prognosis for systemic scleroderma depends mainly on the severity of vascular changes in the organs. The defeat of the kidneys, after the defeat of the heart and lungs, is an unfavorable prognostic factor. The most serious prognosis is with the development of acute scleroderma nephropathy, which remains the leading cause of death in systemic scleroderma. About 60% of patients with this form of scleroderma nephropathy need a temporary hemodialysis (defined as dialysis performed less than 3 months) at the time of the greatest severity of the process.

Most patients recover kidney function, but approximately 20% of them have moderate renal failure, which is associated with an unfavorable prognosis (early death or treatment with program hemodialysis). Other prognostically unfavorable factors are male sex, senior age, scleroderma, a failure to control blood pressure within 72 hours from the onset of an acute situation, a blood creatinine level above 3 mg / dL, preceding the development of a true scleroderma kidney. Chronic scleroderma nephropathy has a more favorable prognosis, but even with this variant of kidney damage the life expectancy of patients is less than in patients without nephropathy.