Scleroderma and kidney damage: diagnosis

Laboratory diagnosis of scleroderma and kidney damage

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.

Scleroderma nephropathy is characterized by an increase in plasma renin level, which in some cases is detected even in patients with mild arterial hypertension or normal arterial pressure. In 30% of patients with true scleroderma nephropathy, microangiopathic hemolytic anemia develops, which can be diagnosed on the basis of a sudden sharp decrease in hemoglobin and hematocrit, reticulocytosis, increased concentrations of bilirubin and lactate dehydrogenase (LDH) in the blood serum and the detection of schizocytes in the peripheral blood smear.

Instrumental diagnosis of scleroderma and kidney damage

For the diagnosis of microcirculatory vascular lesion in systemic scleroderma, the method of wide-field capillaroscopy of the nail bed is used. It allows revealing the expansion and tortuosity of the capillary loops, reduction of the capillary network (reduction of the number of capillaries, "avascular fields").

Assess the state of renal blood flow allows a modern non-invasive method of ultrasound dopplerography of the intrarenal arteries, through which it is possible to identify violations before the development of clinical manifestations of scleroderma nephropathy.

Differential diagnosis of scleroderma

In the formulation of the diagnosis of systemic scleroderma, the clinical symptomatology of the disease is crucial. The American Rheumatological Association proposed simple diagnostic criteria for systemic scleroderma, including:

• "Big" criteria:
  • proximal scleroderma - scleroderma skin lesions proximal to the metacarpophalangeal joints, extending to the thorax, neck and face;
• "Small criteria":
  • sclerodactyly;
  • digital ulcers or scars on the palmar surface of the nail phalanx of the fingers;
  • bilateral basal fibrosis of the lungs.

Diagnosis of scleroderma is based on a combination of a large and at least two small criteria. The appearance of signs of kidney damage in patients with an established diagnosis of systemic scleroderma indicates the development of scleroderma nephropathy. The diagnosis of a true scleroderma kidney is not in doubt with the development of acute renal failure, combined with severe or malignant arterial hypertension, in patients with systemic scleroderma. However, the same clinical picture that developed in the debut of the disease, even before verification of the diagnosis of systemic scleroderma, presents significant diagnostic difficulties. In this situation, a characteristic triad of early signs of systemic scleroderma can help to clarify the diagnosis: Raynaud's syndrome, articular syndrome (more often - polyarthralgia) and dense skin edema. In addition, it is important to detect specific antibodies - anti- centromeric, antitomeric, anti-RNA polymerase. The last two groups of antibodies are most often detected in the diffuse cutaneous form of systemic scleroderma and are associated with an unfavorable prognosis.

Another important diagnostic method in this case is a kidney biopsy. It will allow to differentiate the true scleroderma kidney from other diseases occurring with acute renal failure - acute interstitial nephritis, hemolytic-uremic syndrome. Chronic scleroderma nephropathy should be differentiated from the drug pathology of the kidneys, the development of which is possible with the treatment of systemic scleroderma with penicillamine. Penicillamine therapy can lead to the development of a nephrotic syndrome, in some cases with signs of impaired renal function. Morphologically, a picture of membranous nephropathy is revealed. Abolition of the drug with a subsequent increase in the dose of prednisolone leads to the elimination of nephrotic syndrome, the disappearance of proteinuria and the normalization of kidney function.

[1], [2], [3], [4], [5], [6],