Amyloidosis: A Guide for Junior Doctors

Introduction

Amyloidosis is a group of disorders caused by the deposition of amyloid, an abnormal protein, in various tissues and organs. Its clinical presentation is highly variable, ranging from asymptomatic organ involvement to life-threatening multi-organ failure. This variability can make diagnosis challenging. This blog post will guide junior doctors through history-taking, examination, investigations, and management of amyloidosis.

History-Taking

Amyloidosis requires a detailed and focused history to uncover clues suggestive of the disease. Key questions include:

Presenting Complaints

·       Systemic symptoms: Ask about fatigue, weight loss, and unexplained fevers.

·       Cardiac symptoms:

o   Shortness of breath on exertion or at rest.

o   Orthopnea or paroxysmal nocturnal dyspnea (heart failure symptoms).

o   Palpitations or syncope (arrhythmias).

·       Renal symptoms:

o   Swelling in legs or face (nephrotic syndrome).

o   Decreased urine output.

·       Gastrointestinal symptoms:

o   Altered bowel habits (diarrhea or constipation).

o   Early satiety, nausea, or unintentional weight loss (gastroparesis).

·       Neurological symptoms:

o   Peripheral neuropathy: numbness, tingling, or weakness in hands/feet.

o   Carpal tunnel syndrome: pain and paresthesia in the hands.

Past Medical History

·       Chronic inflammatory or infectious conditions: Rheumatoid arthritis, tuberculosis, or inflammatory bowel disease.

·       Plasma cell dyscrasias: Ask about known multiple myeloma or monoclonal gammopathy of undetermined significance (MGUS).

Drug History

·       Medications associated with systemic diseases, e.g., immunosuppressants or chemotherapy drugs.

Family History

·       Any relatives with amyloidosis or systemic hereditary diseases like familial Mediterranean fever.

Social History

·       Occupational exposure to chronic infections or repetitive physical stressors.

·       Ethnicity, as some hereditary forms are more prevalent in certain populations.

Examination Findings

Amyloidosis can present with multi-system involvement. Conduct a thorough examination, focusing on the following:

·       General

·       Cachexia (unintentional weight loss).

·       Pallor or jaundice.

·       Periorbital purpura (characteristic raccoon eyes).

·       Cardiovascular

·       Raised jugular venous pressure (JVP).

·       Displaced apex beat or signs of restrictive cardiomyopathy.

·       Tachycardia or irregular pulse (arrhythmias).

·       Abdominal

·       Hepatomegaly or splenomegaly.

·       Ascites (due to portal hypertension or nephrotic syndrome).

·       Renal

·       Edema (periorbital, sacral, or peripheral).

·       Neurological

·       Peripheral neuropathy: diminished sensation or strength in extremities.

·       Positive Tinel’s or Phalen’s test (carpal tunnel syndrome).

·       Skin

·       Bruising with minimal trauma.

·       Waxy papules or plaques.

Investigations

Amyloidosis diagnosis hinges on detecting amyloid deposits and identifying the underlying cause.

Baseline Tests

·       Bloods:

·       Full blood count (anemia).

·       Renal function tests (elevated creatinine, reduced eGFR).

·       Liver function tests (alkaline phosphatase elevation).

·       Serum and urine electrophoresis with immunofixation (detect monoclonal proteins).

·       NT-proBNP/Troponin T (cardiac involvement).

·       Urinalysis

·       Proteinuria (indicative of nephrotic syndrome).

·       Imaging

·       Echocardiogram: Wall thickening, diastolic dysfunction, or reduced ejection fraction.

·       MRI (Cardiac): Characteristic late gadolinium enhancement in amyloid cardiomyopathy.

·       CT or ultrasound: For organomegaly or ascites.

·       Specialized Tests

·       Tissue biopsy:

o   Fat pad aspiration (abdominal).

o   Biopsy of affected organs (e.g., kidney, liver, or heart).

o   Congo red staining: Apple-green birefringence under polarized light confirms amyloid deposition.

·       Genetic testing: For hereditary forms.

·       Bone marrow biopsy: If plasma cell dyscrasia is suspected.

Management Plan

Management depends on the type of amyloidosis (AL, AA, ATTR, etc.), the organs involved, and the severity of the disease.

General Principles

·       Supportive care: Treat organ-specific complications, such as diuretics for heart failure or ACE inhibitors for proteinuria.

·       Multidisciplinary approach: Collaborate with cardiology, nephrology, hematology, and gastroenterology specialists.

Specific Management

·       AL Amyloidosis (plasma cell dyscrasia):

o   Chemotherapy (e.g., cyclophosphamide, bortezomib, dexamethasone).

o   Autologous stem cell transplantation in eligible patients.

·       AA Amyloidosis (secondary to chronic inflammation):

o   Treat the underlying inflammatory condition (e.g., rheumatoid arthritis or tuberculosis).

o   Anti-IL-1 agents or biologics for autoimmune diseases.

·       ATTR Amyloidosis (transthyretin):

o   Tafamidis or patisiran (specific therapies).

o   Consider liver transplantation in hereditary cases.

Prognosis and Monitoring

·       Regular follow-up with echocardiography, renal function tests, and serum biomarkers.

·       Monitor response to therapy using biomarkers (e.g., serum free light chains in AL amyloidosis).