A 22-year-old man comes to the clinic due to worsening bilateral lower extremity swelling over the past 3 weeks. He reports that his urine has become very frothy. He has no other chronic medical conditions but has experienced recurrent, self-limited episodes of fever and severe, diffuse abdominal pain since childhood. During these episodes, which occur 2 to 3 times a year and last 48 to 72 hours, he also occasionally develops right ankle swelling and pain. He recently moved to the United States from Turkey and has not had a primary care provider in several years. His parents are first cousins. Vital signs are within normal limits. Physical examination reveals moderate ascites and 3+ pitting edema up to the knees.
Laboratory results are as follows:
| Test | Result |
|---|---|
| Hemoglobin | 11.2 g/dL |
| Leukocyte count | 8,400/mm³ |
| Serum creatinine | 1.5 mg/dL |
| Serum albumin | 2.2 g/dL |
| Urinalysis | 4+ protein, no red blood cells |
| 24-hour urine protein | 7.2 g |
A renal biopsy demonstrates amorphous deposits in the mesangium and capillary walls. When stained with Congo red and viewed under polarized light, the deposits exhibit apple-green birefringence. Long-term adherence to which of the following medications would have most effectively prevented this patient's current renal complication?
- ColchicineAnswer
- BIndomethacin
- CMethotrexate
- DPrednisone
- ECyclophosphamide
Answer
The most severe complication of FMF is secondary (AA) amyloidosis, resulting from the chronic hepatic overproduction of the acute-phase reactant serum amyloid A (SAA). Amyloid deposits in the kidney typically manifest as nephrotic syndrome (massive proteinuria, hypoalbuminemia, and severe edema), as seen in this patient. The diagnosis is confirmed by renal biopsy demonstrating amorphous deposits that show characteristic apple-green birefringence under polarized light after Congo red staining.
Continuous, lifelong therapy with colchicine is the standard of care for FMF. Colchicine binds to tubulin, inhibiting microtubule polymerization and thereby disrupting neutrophil chemotaxis and degranulation. It is highly effective not only in decreasing the frequency and severity of acute FMF attacks but also in completely preventing the development of AA amyloidosis.