Renal Amyloidosis


Renal amyloidosis

Description, Causes and Risk Factors:

In renal amyloidosis, malformed proteins are deposited in the kidneys, causing progressive kidney disease and kidney failure. There are more than 20 known proteins that can cause renal amyloidosis. All proteins have a three-dimensional structure that is dictated by chemical interactions between different amino acids in the protein chain. Abnormally structured protein will not perform its function in a normal way. Renal amyloidosis may occur when any factor causes one or several proteins fold incorrectly.

The most important predisposing factor for the development of lupus nephritis is the presence of systemic amyloidosis. This may occur as a hereditary amyloid disorder or more frequently secondary to another medical condition such as certain infections, certain forms of cancer and long-term dialysis therapy for renal failure. A family history of amyloid disease is therefore an important risk factor of disease.

The presence of conditions causing secondary amyloidosis is also a predisposing factor for amyloid nephritis. These include:

    Multiple myeloma and other malignancies.

  • Long-term infections such as tuberculosis, osteomyelitis and leprosy.

  • Chronic inflammatory disorders such as rheumatoid arthritis.

Renal amyloidosis is encountered not infrequently in the practice of nephrology, although its incidence has varied from 3 to 12 % in different published renal biopsy series, there being a tendency for its incidence to fall as the size of the series reported increases. Considerable variations are also found in published accounts concerning the relative incidence of the various diseases associated with secondary amyloidosis. These variations probably result chiefly from differences in referral patterns and the special interests of the centres concerned. In the United Kingdom, tuberculosis remains an important cause of secondary amyloidosis, accounting for 24% of 80 consecutive patients with renal amyloidosis, and for 50% of 40 cases reported from Scotland. In two series published from England, "primary" amyloidosis was responsible for approximately 20% of 98 cases in which the diagnosis of amyloidosis was made by renal biopsy." It is noteworthy that amyloid is often unsuspected when the renal biopsy is performed, usually in the nephrotic syndrome or because of unexplained renal failure. Routine examination for amyloid in renal biopsies is therefore mandatory.

The clinical and bioch

Symptoms:

    Proteinuria is early manifestation of renal amyloidosis and may last for years.

  • Nephrotic Syndrome.

  • Renal insufficiency.

  • Renal interstitial-tubular nephritis, which causes symptoms including excessive urine output, increasing urine phosphate excretion, renal tubular acidosis, electrolyte disorders, etc.

Diagnosis:

Your doctor may discover that you have an enlarged liver or spleen.If organ damage is suspected, your doctor may order tests to confirm amyloidosis of that organ. For example:

    Abdominal ultrasound may reveal a swollen liver or spleen.

  • An abdominal fat pad aspiration, rectal mucosa biopsy, or bone marrow biopsy can help confirm the diagnosis.

  • A heart evaluation, including an ECG, may reveal arrhythmias, abnormal heart sounds, or signs of congestive heart failure. An echocardiogram shows poor motion of the heart wall, due to a stiff heart muscle.

Tests:

    Test of M-protein. It is used to diagnose and confirm the type of M-proteinemia.

  • Tests of kidney damage. It works to confirm the kidney damage part and offer basis for the following treatment plan. It includes UTP, U-malb, U-TRF, U-IGG, ? 2-microglobulin, ?1-microglobulin, ?2-macroglobulin, ? light chain, ? light chain, U-NAG, U-GGT, and Uosm.

  • Toxins in Blood Tests. The tests include the items of BUN, creatinine, UA, ? 2-microglobulin, Cyc C, RBP, HCY, and PTH, which are ordered to make the buildup of toxins in the body clear.

  • Abnormally elevated serum apoE level is the most featured index of lab test for lipoprotein glomerulopathy. Serum free fatty acids can reflect the human body fat metabolism and blood fat level.

  • Blood lipid tests, which includes triglyceride, total cholesterol, HDL, LDL, Apo A1, Apo BT, lipoprotein a.

  • Series of sugar metabolism test. Aim: index to judge the dysfunction of human body metabolism; produce index for clinical treatment and treatment effect, including blood sugar, HbA1c, insulin, and C-peptide.

Early diagnosis and classification of amyloid deposition and differentiation from other glomerular fibrillar deposits relies on routine Congo red (CR) histochemistry. Congo red fluorescence (CRF) is an alternative method based on examination of the CR-stained section by ultraviolet (UV) light. The aim of this study is to investigate the usefulness of CRF, especially when applied to frozen kidney sections. Congo red fluorescence was applied to sections of frozen kidney biopsies prospectively and to paraffin sections retrospectively. The findings of CRF were compared to CR staining in bright light. Prospectively, 15 cases of amyloidosis were diagnosed on frozen sections and identical CR staining was found in all of the paraffin-stained sections. There were no false positives or negatives. Retrospectively, 146 renal biopsies previously stained with CR were re-evaluated with CRF. Eighty-seven CR positive cases were confirmed by CRF, and one new case was identified. Congo red fluorescence is simple to perform and more pronounced, therefore easier to evaluate than CR in bright light. Congo red, when combined with immunohistochemistry, is still visible under UV whereas CR is masked in bright light. Although not widely used, the CRF method for detecting amyloid is simple to use with a high specificity and sensitivity, and may be applied successfully to frozen sections.

Treatment:

Some patients with primary amyloidosis respond to chemotherapy focused on the abnormal plasma cells. A stem cell transplant may be done, as in multiple myeloma. In secondary amyloidosis, aggressively treating the disease that is causing the excess amyloid protein can improve symptoms and/or slow the disease from getting worse. Complications such as heart failure, kidney failure, and other problems can sometimes be treated, when needed.

Tremendous advances have been made during the past several years in elucidating the structure and the chemistry of amyloid proteins, the mechanisms of fibril formation and tissue deposition, and the processes involved in tissue injury. This increased understanding has been accompanied by progress in developing novel treatment approaches that are directed not only at the source of the precursor protein but also at each of the steps in the pathway from precursor protein production to amyloid degradation. Small molecules that stabilize precursor proteins in their native conformation and thereby prevent generation of the misfolded variants have been identified. Enhancing amyloid mobilization from tissue by targeting components of amyloid deposits that protect fibrils from proteolysis is yet another strategy under development. Ultimately, one can envision multipronged approaches composed of treatments that are directed at several different targets.

NOTE: The above information is for processing purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.

DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.

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