Diagnosis of amyloidosis requires tissue biopsy. The biopsy is assessed for evidence of characteristic amyloid deposits. The tissue is treated with various stains. The most useful stain in the diagnosis of amyloid is Congo red, which, combined with polarized light, makes the amyloid proteins appear apple-green on microscopy. Also, thioflavin T stain may be used.

Tissue can come from any involved organ, but in systemic disease the first-line site of the biopsy is subcutaneous abdominal fat, known as a "fat pad biopsy," due to its ease of acquisition versus biopsy of the rectum, salivary gland or internal organs. An abdominal fat biopsy is not completely sensitive, and sometimes, biopsy of an involved organ (such as the kidney) is required to achieve a diagnosis. For example, in AL amyloidosis only 85% of people will have a positive fatpad biopsy using Congo red stain. By comparison, rectal biopsy has sensitivity of 74–94%.

The type of the amyloid protein can be determined in various ways: the detection of abnormal proteins in the bloodstream (on protein electrophoresis or light chain determination); binding of particular antibodies to the amyloid found in the tissue (immunohistochemistry); or extraction of the protein and identification of its individual amino acids. Immunohistochemistry can identify AA amyloidosis the majority of the time, but can miss many cases of AL amyloidosis. Laser microdissection with mass spectrometry is the most reliable method of identifying the different forms of amyloidosis.

AL is the most common form of amyloidosis, and a diagnosis often begins with a search for plasma cell dyscrasia, memory B cells producing aberrant immunoglobulins or portions of immunoglobulins. Immunofixation electrophoresis of urine or serum is positive in 90% of people with AL amyloidosis. Immunofixation electrophoresis is more sensitive than regular electrophoresis but may not be available in all centers. Alternatively immunohistochemical staining of a bone marrow biopsy looking for dominant plasma cells can be sought in people with a high clinical suspicion for AL amyloidosis but negative electrophoresis.

ATTR, or familial transthyretin-associated amyloidosis, is suspected in people with family history of idiopathic neuropathies or heart failure who lack evidence of plasma cell dyscrasias. ATTR can be identified using isoelectric focusing which separates mutated forms of transthyretin. Findings can be corroborated by genetic testing to look for specific known mutations in transthyretin that predispose to amyloidosis.

AA is suspected on clinical grounds in individuals with longstanding infections or inflammatory diseases. AA can be identified by immunohistochemistry staining.

Prognosis varies with the type of amyloidosis. Prognosis for untreated AL amyloidosis is poor with median survival of one to two years. More specifically, AL amyloidosis can be classified as stage I, II or III based on cardiac biomarkers like troponin and BNP. Survival diminishes with increasing stage, with estimated survival of 26, 11 and 3.5 months at stages I, II and III, respectively.

Outcomes in a person with AA amyloidosis depend on the underlying disease and correlate with the concentration of serum amyloid A protein.

People with ATTR have better prognosis and may survive for over a decade.

Senile systemic amyloidosis was determined to be the primary cause of death for 70% of people over 110 who have been autopsied.

Median survival for patients diagnosed with AL amyloidosis was 13 months in the early 1990s, but had improved to c. 40 months a decade later.

Both blood and the urine can be tested for the light chains, which may form amyloid deposits, causing disease. However, the diagnosis requires a sample of an affected organ.

LECT2 amyloidosis is diagnosed by a kidney biopsy which reveals two key findings: a) histological evidence of Congo red staining material deposited in the interstitial, mesangial, glomerular, and/or vascular areas of the kidney and b) the identification of these deposits as containing mainly ALECT2 as identified by proteomics methodologies. Kidney biopsy shows the presence of LECT2-based amyloid predominantly in the renal cortex interstitium, glomeruli, and arterioles. LECT2 amyloidosis can be distinguished from AL amyloidosis, the most common form of amyloidosis (~85% of total cases), by testing their blood for the presence of high levels of a clonal immunoglobulin light chain. If the patient tests negative for this light chain, positive Congo Red staining of the kidney biopsy strongly suggests LECT2 amyloidosis.

Based on studies conducted in the United States, the prognosis for individuals with ALECT2 amyloidosis is guarded, particularly because they are elderly and their kidney disease is usually well-advanced at the time of presentation. End-stage renal disease develops in 1 out of 3 patients and has a median renal survival of 62 months. A suggested prognostic tool is to track creatinine levels in ALect2 patients. The attached Figure gives survival plotss for individuals with LECT2 renal amyloidosis and serum creatinine levels less than 2 mg/100 ml versus 2 mg/100 ml or greater than 2 mg/100 ml. The results show that afflicted individuals with lower creatinine levels have a ~four-fold higher survival rate.

The condition is suspected in an elderly person, especially male, presenting with symptoms of heart failure such as shortness of breath or swollen legs, and or disease of the electrical system of the heart with ensuing slow heart rate, dizziness or fainting spells. The diagnosis is confirmed on the basis of a biopsy, which can be treated with a special stain called Congo Red that will be positive in this condition, and immunohistochemistry.

In a healthy individual, the median plasma concentration of SAA is 3 mg per liter. This can increase to over 2000 mg per liter during an acute phase response and a sustained overproduction of SAA is required for the creation of the AA deposits that define AA amyloidosis. High levels of SAA, however, is not a sufficient condition for the development of systemic AA amyloidosis and it remains unclear what triggers the accumulation of AA.

The AA protein is mainly deposited in the liver, spleen and kidney, and AA amyloidosis can lead to nephrotic syndrome and ESRD. Natural history studies show, however, that it is the renal involvement that drives the progression of the disease. In general, old age, reduced serum albumin concentration, end stage renal failure, and sustained elevated SAA concentration are all associated with poor prognosis.

There are currently no approved treatments for systemic AA amyloidosis. The current standard of care includes treatments for the underlying inflammatory disease with anti-inflammatory drugs, immunosuppressive agents or biologics. AA amyloidosis patients are also receiving treatments to slow down the decline of their renal function, such as angiotensin II receptor blockers or angiotensin converting enzyme inhibitors.

Kiacta - (eprodisate disodium) is in 2015 being evaluated as a protector of renal function in AA amyloidosis. Kiacta, inhibits the formation and deposition of the amyloid A fibrils into the tissues.

No drug has been shown to be able to arrest or slow down the process of this condition. There is promise that two drugs, tafamidis and diflunisal, may improve the outlook, since they were demonstrated in randomized clinical trials to benefit patient affected by the related condition FAP-1 otherwise known as transthyretin-related hereditary amyloidosis. Permanent pacing can be employed in cases of symptomatic slow heart rate (bradycardia). Heart failure medications can be used to treat symptoms of difficulty breathing and congestion.

The median time to progression to end stage renal disease is 2.7 years. After 5 years, about 37% of patients with LCDD are alive and do not have end stage renal disease.

Although not based on a human clinical trial, the only currently accepted disease-modifying therapeutic strategy available for familial amyloid cardiomyopathy is a combined liver and heart transplant. Treatments aimed at symptom relief are available, and include diuretics, pacemakers, and arrhythmia management. Thus, Senile systemic amyloidosis and familial amyloid polyneuropathy are often treatable diseases that are misdiagnosed.

In 2013, the European Medicines Agency approved the drug tafamidis (Vyndaqel) to slow the progression of familial amyloid polyneuropathy, a related disease caused by TTR aggregation that first presents as an autonomic and/or peripheral neuropathy (later progressing to a cardiomyopathy).

Organ-limited amyloidosis is a category of amyloidosis where the distribution can be associated primarily with a single organ. It is contrasted to systemic amyloidosis, and it can be caused by several different types of amyloid.

In almost all of the organ-specific pathologies, there is significant debate as to whether the amyloid plaques are the causal agent of the disease or instead a downstream consequence of a common idiopathic agent. The associated proteins are indicated in parentheses.

There is no standard treatment for LCDD. High-dose melphalan in conjunction with autologous stem cell transplantation has been used in some patients. A regimen of bortezomib and dexamethasone has also been examined.

Liver transplantation has proven to be effective for ATTR familial amyloidosis due to Val30Met mutation.

Alternatively, a European Medicines Agency approved drug Tafamidis or Vyndaqel now exists which stabilizes transthyretin tetramers comprising wild type and different mutant subunits against amyloidogenesis halting the progression of peripheral neuropathy and autonomic nervous system dysfunction.

Currently there are two ongoing clinical trials undergoing recruitment in the United States and worldwide to evaluate investigational medicines that could possibly treat TTR.

Although there are no definitive criteria to diagnose the existence of reactive arthritis, the American College of Rheumatology has published sensitivity and specificity guidelines.

Familial renal amyloidosis (or familial visceral amyloidosis, or hereditary amyloid nephropathy) is a form of amyloidosis primarily presenting in the kidney.

It is associated most commonly with congenital mutations in the fibrinogen alpha chain and classified as a dysfibrinogenemia (see Hereditary Fibrinogen Aα-Chain Amyloidosis). and, less commonly, with congenital mutations in apolipoprotein A1 and lysozyme.

It is also known as "Ostertag" type, after B. Ostertag, who characterized it in 1932 and 1950.

There are few clinical symptoms, but the clinical picture is dominated by arthritis in one or more joints, resulting in pain, swelling, redness, and heat sensation in the affected areas.

The urethra, cervix and the throat may be swabbed in an attempt to culture the causative organisms. Cultures may also be carried out on urine and stool samples or on fluid obtained by arthrocentesis.

Tests for C-reactive protein and erythrocyte sedimentation rate are non-specific tests that can be done to corroborate the diagnosis of the syndrome.

A blood test for the genetic marker HLA-B27 may also be performed. About 75 percent of all the patients with Reiter's arthritis have this gene.

Secondary systemic amyloidosis is a condition that involves the adrenal gland, liver, spleen, and kidney as a result of amyloid deposition due to a chronic disease such as Behçet's disease, ulcerative colitis, etc.

The onset of FAC caused by aggregation of the V122I mutation and wild-type TTR, and senile systemic amyloidosis caused by the exclusive aggregation of wild-type TTR, typically occur after age 60. Greater than 40% of these patients present with carpal tunnel syndrome before developing ATTR-CM. Cardiac involvement is often identified with the presence of conduction system disease (sinus node or atrioventricular node dysfunction) and/or congestive heart failure, including shortness of breath, peripheral edema, syncope, exertional dyspnea, generalized fatigue, or heart block. Unfortunately, echocardiographic findings are indistinguishable from those seen in AL amyloidosis, and include thickened ventricular walls (concentric hypertrophy, both right and left) with a normal-to-small left ventricular cavity, increased myocardial echogenicity, normal or mildly reduced ejection fraction (often with evidence of diastolic dysfunction and severe impairment of contraction along the longitudinal axis), and bi-atrial dilation with impaired atrial contraction. Unlike the situation in AL amyloidosis, the ECG voltage is often normal, although low voltage may be seen (despite increased wall thickness on echocardiography). Marked axis deviation, bundle branch block, and AV block are common, as is atrial fibrillation.

Elevated creatine kinase (CK) levels in the blood (at most ~10 times normal) are typical in sIBM but affected individuals can also present with normal CK levels. Electromyography (EMG) studies usually display abnormalities. Muscle biopsy may display several common findings including; inflammatory cells invading muscle cells, vacuolar degeneration, inclusions or plaques of abnormal proteins. sIBM is a challenge to the pathologist and even with a biopsy, diagnosis can be ambiguous.

A diagnosis of inclusion body myositis was historically dependent on muscle biopsy results. Antibodies to cytoplasmic 5'-nucleotidase (cN1A; NT5C1A) have been strongly associated with the condition. In the clinical context of a classic history and positive antibodies, a muscle biopsy might be unnecessary.

IBM is often initially misdiagnosed as polymyositis. A course of prednisone is typically completed with no improvement and eventually sIBM is confirmed. sIBM weakness comes on over months or years and progresses steadily, whereas polymyositis has an onset of weeks or months. Other forms of muscular dystrophy (e.g. limb girdle) must be considered as well.

Amyloid cardiomyopathy (stiff heart syndrome) is associated with the systemic production and release of many amyloidogenic proteins, especially immunoglobulin light chain or transthyretin (TTR). It can be characterized by the extracellular deposition of amyloid in the heart. Amyloids are foldable proteins that all stick together to build fibrils.

The aggregation of one precursor protein leads to peripheral neuropathy and/or autonomic nervous system dysfunction. These proteins include: transthyretin (ATTR, the most commonly implicated protein), apolipoprotein A1, and gelsolin.

Due to the rareness of the other types of familial neuropathies, transthyretin amyloidogenesis-associated polyneuropathy should probably be considered first.

"FAP-I" and "FAP-II" are associated with transthyretin. (Senile systemic amyloidosis [abbreviated "SSA"] is also associated with transthyretin aggregation.)

"FAP-III" is also known as "Iowa-type", and involves apolipoprotein A1.

"FAP-IV" is also known as "Finnish-type", and involves gelsolin.

Fibrinogen, apolipoprotein A1, and lysozyme are associated with a closely related condition, familial visceral amyloidosis.

The diagnosis is clinically made on the basis of the history of typical attacks, especially in patients from the ethnic groups in which FMF is more highly prevalent. An acute phase response is present during attacks, with high C-reactive protein levels, an elevated white blood cell count and other markers of inflammation. In patients with a long history of attacks, monitoring the kidney function is of importance in predicting chronic kidney failure.

A genetic test is also available to detect mutations in the "MEFV" gene. Sequencing of exons 2, 3, 5, and 10 of this gene detects an estimated 97% of all known mutations.

A specific and highly sensitive test for FMF is the "Metaraminol Provocative Test (MPT)," whereby a single 10 mg infusion of Metaraminol is administered to the patient. A positive diagnosis is made if the patient presents with a typical, albeit milder, FMF attack within 48 hours. As MPT is more specific than sensitive, it does not identify all cases of FMF. Although a positive MPT can be very useful.