Scleroderma and kidney damage

Systemic scleroderma is a polysyndromic autoimmune disease characterized by progressive fibrosis and widespread vascular pathology such as obliterating microangiopathy, which underlie generalized Raynaud's syndrome, skin lesions, and internal organs (lungs, heart, gastrointestinal tract, kidneys).

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Epidemiology

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

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Pathogenesis

Scleroderma nephropathy is a vascular pathology of the kidneys caused by occlusive damage to the intrarenal vessels, leading to organ ischemia and manifested by arterial hypertension and renal dysfunction of varying severity.

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

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

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Symptoms systemic scleroderma

Kidney damage in systemic scleroderma most often develops in patients with diffuse cutaneous form of the disease, with its acute progressive course, within 2 to 5 years from the onset, although nephropathy may also develop with chronic slowly progressive 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 is combined with arterial hypertension and/or renal dysfunction. Nephrotic syndrome develops extremely rarely.

True scleroderma kidney

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 the diffuse cutaneous form of scleroderma with a progressive course (rapid progression of skin lesions over several months). Additional risk factors are old and senile age, male gender, and belonging to the Negroid race. They are also unfavorable in terms of the prognosis of acute scleroderma nephropathy.

Diagnostics systemic scleroderma

Laboratory examination of patients with systemic scleroderma may reveal anemia, moderate increase in ESR, leukocytosis or leukopenia, hyperproteinemia with hypergammaglobulinemia, elevated levels of C-reactive protein and fibrinogen.

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

These include:

• antitopoisomerase (previous name - aHTH-Scl-70), detected mainly in the diffuse cutaneous form of systemic scleroderma;
• anticentromere - in 70-80% of patients with a limited form of systemic scleroderma;
• anti-RNA polymerase - associated with a high incidence of kidney damage.

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Treatment systemic scleroderma

In the case of low-symptom kidney damage, which is observed in most patients with systemic scleroderma, special treatment may not be required in the case of normal blood pressure. The development of moderate arterial hypertension is an indication for the initiation of antihypertensive therapy. The drugs of choice are ACE inhibitors, which suppress the increased plasma renin activity in scleroderma nephropathy.

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

Forecast

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

Most patients recover renal function, but about 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 include male gender, older age, scleroderma heart disease, inability to control blood pressure for 72 hours from the onset of the acute situation, and a blood creatinine level greater than 3 mg / dL preceding the development of 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 shorter than that of patients without nephropathy.