A COMPLEX CASE OF RENAL AMYLOIDOSYS: DIAGNOSTIC CHALLENGES IN A DEVELOPING COUNTRY

Introduction:

Amyloidosis, a rare disorder of misfolded protein deposition, was diagnosed by kidney biopsy in a 50-year-old male with multiorgan dysfunction after herbal medicine use. This case highlights the importance of considering amyloidosis in unexplained multiorgan dysfunction when common causes are ruled out

Methods:

A 50-year-old male was referred to the Nephrology Clinic due to elevated serum creatinine levels. A year prior, he had elevated liver enzymes and jaundice, but the diagnosis and treatment were unknown. Two months pre-admission, he took unidentified herbal medicine, leading to jaundice, dark urine, and pruritus. Initial tests revealed serum creatinine at 3.19 mg/dL, rising to 4.85 mg/dL a week later, leading to hospitalization.

On examination, hepatomegaly (3 cm below the costal margin) and low back pain were noted, with no fever, rash, chest pain, dyspnea, or edema. Laboratory tests indicated liver and renal dysfunction (Table 1). Ultrasound showed normal kidneys and an enlarged homogeneous liver. X-ray showed lumbar spondylosis. Abdominal MRI ruled out billiary obstruction, showing mild periportal edema, diffuse hepatomegaly, and no abnormal liver parenchyma signals.

Given the multiorgan involvement, systemic diseases were considered, but an autoimmune panel and immunofixation electrophoresis were negative. Bone marrow aspiration showed one plasma cell. Amyloidosis remained the only diagnosis after excluding other possibilities. While we conducted all the laboratory tests, the patient’s kidney function and cholestasis worsened (Figure 1). New lung involvement was detected. Bronchoalveolar lavage was negative. The patient was planned for kidney and liver biopsies. The kidney biopsy ultimately confirmed amyloidosis (Figure 2), leading to cancellation of the liver biopsy. Unforunately, due to the lack of specific antibodies for immunohistochemical staining in our center and country, we unable to classify the amyloidosis type. The four main types of renal amyloidosis are AL, AA, ATTR, and ALECT2, with their clinical presentations summarized in Table 2. Speckle tracking echocardiography was performed to evaluate cardiac involvement, with the results shown in Figure 3. Genetic testing of over 4500 genes excluded variant transthyretin amyloidosis, while wild-type transthyretin amyloidosis was ruled out based on the patient's age. AL amyloidosis was strongly suspected because negative results from blood tests and renal biopsy do not exclude immunoglobulin amyloidosis. Immunofluorescence and immunoperoxidase techniques have limitations in diagnosing immunoglobulin amyloidosis, with 7 – 35% of renal deposits potentially negative for both λ and κ light chains. Immunofluorescence offers 85% sensitivity and 92% specificity. Furthermore, given urgency to prevent further organ damage, we decided to initiate a Mel – Dex regimen (Melphalan 10 mg/m², dexamethasone 40 mg)

Results:

After five cycles of Mel – Dex, kidney function improved (creatinine 3.3 mg/dL, PCR 170 mg/mmol) and liver function nearly normalized (total bilirubin 1.2 mg/dL)

Conclusions:

This case emphasizes the importance of thorough investigation and medical history in diagnosing unexplained multiorgan dysfunction, suggesting systemic disease. Amyloidosis diagnosis remains challenging, especially in developing countries like Vietnam with limited lab capabilities

I have no potential conflict of interest to disclose.

I did not use generative AI and AI-assisted technologies in the writing process.