Different renal pathologies can have the same clinical presentation, and different clinical presentations can have the same renal pathology. The severity of clinical proteinuria and hematuria in no way reflects the severity of renal pathology. For example, a small amount of proteinuria or hematuria can be sclerosing glomerulonephritis, when the majority of glomeruli are abandoned so that proteinuria and red blood cells cannot leak out, so proteinuria or hematuria can be mild, and once diagnosed, the prognosis is poor; whereas a large amount of proteinuria or hematuria can be microscopic lesion type or mild thylakoid glomerulonephritis, which has a good prognosis. The prognosis is good with timely intervention. Therefore, renal biopsy is the only gold standard to confirm the diagnosis of kidney disease and determine the prognosis, and it is also the most important objective basis to guide the clinical use of drugs.
Since 2002, the Department of Nephrology of Lu’an Hospital of Traditional Chinese Medicine has been independently carrying out renal biopsy, and in 2008, it started to carry out renal pathology independently, and now this technology has been perfected and can meet the need of confirming the diagnosis in most cases. Now we have completed more than 400 cases of kidney biopsy pathology examination, which has greatly improved the level of kidney disease diagnosis and treatment in Lu’an area, and won the third prize of municipal science and technology progress in 2009.
Indications for kidney biopsy pathology examination
With the increasing maturity and safety of renal biopsy technology, the indications for renal biopsy have been significantly relaxed. Any person with diffuse renal parenchymal damage, whose etiology, nature and extent of pathological changes, treatment and prognosis have not been resolved or are not clear, is an indication for renal biopsy. The main purpose of renal biopsy is to clarify the diagnosis and guide treatment; therefore, the clinical significance of renal biopsy is not the same in different patients. The clinical significance of renal biopsy is greatest when it is helpful for both diagnosis and treatment, such as adult nephrotic syndrome; in some patients, the clinical diagnosis is basically clear, but renal biopsy can provide great help for disease typing and individualized treatment, and its clinical significance is also great, such as lupus nephritis and systemic vasculitis. The vast majority of patients can have a definite or corrected diagnosis after renal biopsy, and less than 2% of patients still cannot have a definite diagnosis. The indications for renal biopsy pathology are as follows.
(a) Nephrotic syndrome: Nephrotic syndrome has multiple etiologies and pathological changes, especially in adults, and it is often difficult to make a clear diagnosis based on clinical features alone. More than half of the patients with adult nephrotic syndrome have had their diagnosis revised and their treatment regimen adjusted after renal biopsy. Therefore, all adult nephrotic syndrome should be treated after renal biopsy to clarify the type of pathology and to determine the prognosis. In children with nephrotic syndrome who are insensitive to hormone therapy or hormone dependent, renal biopsy should also be performed early to clarify the diagnosis.
(b) Acute and acute nephritis syndrome: a variety of primary or secondary glomerulonephritis, vasculitis and other diseases can cause hematuria, proteinuria, swelling, hypertension (acute nephritis syndrome) or rapid deterioration of renal function (acute nephritis syndrome) should be renal biopsy to clarify the cause and pathological type. Although the diagnosis of post-infectious glomerulonephritis, lupus nephritis, hyperneutrophil cytoplasmic antibody-associated vasculitis or Goodpasture’s syndrome can be basically made on the basis of clinical manifestations and serological examination, renal biopsy can reveal specific pathological changes, assess the degree of reversibility of the lesions and determine the treatment plan. For example, if lupus nephritis is clinically manifested as an acute nephritis syndrome, the pathological changes on renal biopsy may be accompanied by a large number of crescent bodies, lupus vasculopathy, membranous nephropathy, or severe tubulointerstitial lesions in addition to proliferation and inflammation within the diffuse glomerular capillary collaterals, and the pathogenesis, treatment options, and prognosis of these pathological types vary greatly. Although ANCA is a marker for the diagnosis of systemic vasculitis, there are still some vasculitis such as ANCA-negative vasculitis, or vasculitis confined to the kidney that is clinically difficult to identify and requires a renal biopsy for definitive diagnosis.
(iii) Acute renal failure: Acute renal failure due to pre-renal oliguria and urinary tract obstruction does not require renal biopsy, and in most cases acute tubular necrosis can be correctly diagnosed based on clinical findings. Renal biopsy is indicated in cases of non-acute tubular necrosis, where the diagnosis is doubtful or where the disease has not recovered for more than 4 weeks.
(iv) Microscopic hematuria: IgA nephropathy is the most common, but it can also be hereditary nephropathy such as thin basement membrane nephropathy and Alport syndrome. Due to different etiologies, there are great differences in treatment and prognosis. If accompanied by hypertension and swelling, it is mostly focal segmental sclerosing glomerulonephritis, which is an absolute indication for performing renal biopsy.
(E) Proteinuria: nephrotic proteinuria (24-hour protein quantification ≥3.5g) is an absolute indication for renal biopsy. Non-nephrotic proteinuria (24-hour protein quantification <2g), if clinically indicated as diffuse renal damage, should also be diagnosed by renal biopsy, which can exclude some early systemic diseases that only show renal involvement, such as nodular disease, amyloidosis, lupus nephritis, etc.; some patients may have idiopathic focal segmental glomerulosclerosis or idiopathic membranous nephropathy, which can be selected after the diagnosis is confirmed by renal biopsy. Different treatment plans can be chosen after the diagnosis is confirmed by renal biopsy.
(vi) Autoimmune diseases: Almost all autoimmune diseases can involve the kidney, especially systemic lupus erythematosus, scleroderma, mixed connective tissue disease and overlap syndrome. In addition, laboratory tests for lupus nephritis are often not parallel to renal histology; therefore, the treatment plan for lupus nephritis currently depends mainly on the pathological staging of renal biopsy and the renal activity and chronicity index. Renal biopsy pathology is also the most reliable indicator of the prognosis of lupus nephritis.
(vii) Diabetic nephropathy: The diagnosis of diabetic nephropathy may not depend on renal biopsy if the typical diabetic nephropathy, such as long duration of diabetes, predominantly proteinuria in urinalysis, is accompanied by diabetic microangiopathy or neuropathy, and the relative risk of renal biopsy is also greater. About 1/3 of diabetic patients with renal damage may have non-diabetic nephropathy, such as type 2 diabetes combined with membranous nephropathy, IgA nephropathy or crescentic nephritis. Therefore, renal biopsy is required in type 2 diabetes with massive proteinuria, rapidly developing nephropathy, with massive hematuria or manifesting as acute nephritis syndrome.
(H) chronic renal failure: chronic renal failure is a relative contraindication to renal biopsy, but renal biopsy should be considered for mild renal insufficiency, no significant reduction in kidney volume, accompanied by large amounts of proteinuria or hematuria, or clinical suspicion of secondary renal disease with unknown etiology such as amyloidosis, light chain deposition disease, or when the degree of reversibility of the lesion needs to be clarified. 60%-80% of patients with a clear diagnosis by renal biopsy The long-term prognosis is greatly improved with timely intervention. Chronic renal insufficiency should be strictly controlled before kidney biopsy, correct the abnormal bleeding and clotting time, the risk of bleeding is very low.
(ix) Kidney transplantation: renal insufficiency occurs in the early stage of kidney transplantation, after excluding vascular disease and surgical complications, biopsy of the transplanted kidney can clarify whether it is acute tubular necrosis, acute rejection reaction, nephrotoxicity of neurocalciferin inhibitors and other causes of renal insufficiency. In late renal transplantation renal insufficiency, transplant kidney biopsy may identify chronic rejection reaction, neurocalcine inhibitor nephrotoxicity, recurrent nephropathy, or new-onset glomerular disease. Both early and late transplantation kidney damage and kidney biopsy play a key role in guiding the adjustment of treatment. Regular renal biopsies after kidney transplantation are now advocated for early detection of subclinical rejection and thus timely adjustment of therapy.
Kidney biopsy pathology cases
(a) Four 48-year-old male patients with urine protein 2+, the pathological type can be microscopic lesion type.
It can also be IgA nephropathy.
or membranous nephropathy.
It can even be focal segmental sclerosing nephritis
(b) The same urine changes and degree of renal impairment, the same crescentic nephritis, but with different degrees of cellular and fibrous crescentic activity, with very different treatment and prognosis.
(iii) Four female patients with the same lupus nephritis and the same urinary changes, but can be of four different pathological types with very different treatment and prognosis.
Renal biopsy pathology procedure
(A) Renal biopsy operation
(B) Renal pathology examination