A 33-year-old man consulted the nephrology department at the end of 2006 due to an increase in serum creatinine (Crs) to 1.4 mg/dl. He had no history or clinical manifestations of urological or renal disease. Five years earlier, his Crs was 0.9 mg/dl.
At the age of 18 he was diagnosed with iron deficiency anaemia and gastro-oesophageal reflux. In the last 4 years he reported dysphagia and postprandial heaviness, without other gastrointestinal manifestations; also lumbar pain with mechanical characteristics. Absence of febrile episodes, joint inflammation, skin lesions, serositis, or other organs or systems.
Family history of ankylopoietic spondylitis in several males of his paternal branch; a paternal uncle was also diagnosed with stage 5 chronic kidney disease secondary to nephropathy due to analgesic abuse.
Physical examination normal, blood pressure: 130/79 mmHg, body mass index: 21 kg/m2.
Complementary examinations
Blood tests: Crs: 1.47 mg/dl; estimated glomerular filtration rate (eGFR) by MDRD-4: 59 ml/min/1.73 m2; urea: 33 mg/dl; ions, liver enzymes and lipids: normal. Total proteins, proteinogram, immunoglobulins and complement: normal. Rheumatoid factor negative. C-reactive protein (CRP): 13 mg/l (normal value [NRV] < 10 mg/l). Antinuclear antibodies, anti-DNA antibodies, anti-neutrophil cytoplasmic antibodies and histocompatibility antigen-B27 were negative. Iron parameters: sideremia: 25 µg/dl (VN: 40-60); ferritin: 38 ng/ml (VN: 20-300), transferrin saturation index: 12%. Vitamin B12: 181 pg/ml (VN: 208-930) and folic acid: 3.3 ng/ml (VN: 7.2-15).
Urinalysis: proteinuria: 200 mg/24 h; albuminuria: 47 mg/24 h, without monoclonal free light chains. Urine sediment normal.
Chest and spine X-rays without significant alterations. Abdominal, renal and urinary tract ultrasound: normal. The rheumatology department ruled out ankylopoietic spondylitis.
Laboratory tests at 2 months showed: Crs: 1.64 mg/dl; eGFR (MDRD-4): 52 ml/min/1.73 m2; proteinuria: 316 mg/24 h; albuminuria: 163 mg/24 h. And 4 months later: Crs: 1.77 mg/dl; eGFR (MDRD-4): 47 ml/min/1.73 m2; proteinuria: 640 mg/24 h. Deficiencies of iron and vitamins B12 and folic acid were partially corrected with oral supplements.
Given the persistence of gastrointestinal symptoms (dysphagia, dyspepsia) and suspicion of intestinal malabsorption (iron and vitamin deficiencies), we considered an endoscopic study of the gastrointestinal tract with biopsies. The main alterations were found in the mucosa of the terminal ileum: ulcerated villous architecture, lymphoplasmacytic inflammatory reaction in the lamina propria, with neutrophil infiltration (abscesses in crypts) and epithelioid histiocyte granulomas; compatible with CD. In the mucosa of the rectum, in the walls of the blood vessels of the lamina propria, a deposit of material with staining characteristics (congo red and immunohistochemistry) typical of AA amyloidosis was found, without inflammatory signs.
A percutaneous renal biopsy was also performed in view of the unfavourable progression of renal parameters (renal function and proteinuria), which showed: 7 glomeruli, 3 with practically global sclerosis, and the remaining with scant deposits of eosinophilic material in the hilum of the glomerular ring; occasional areas of interstitial fibrosis, and deposit of eosinophilic material in the walls of the blood vessels more extensive and intense than the glomerular ones. The deposits were cone red positive with green birefringence to polarised light and immunohistochemistry determined the presence of amyloid A protein.
This patient did not have, nor has he had in the subsequent evolution, any symptoms or clinical signs suggestive of any other type of inflammatory, infectious or tumour disease, nor familial Mediterranean fever.
With the diagnosis of CD and secondary AA amyloidosis, etiological treatment of CD was decided based on infliximab 5 mg/kg intravenously every 2 months, azathioprine 1-1.5 mg/kg/day (only the first year, suspended due to leukopenia) and a renin-angiotensin-aldosterone system blocker. Renal parameters improved, as well as inflammatory markers (CRP: 5 mg/l, and serum amyloid A protein < 5 mg/l), and are maintained after 4 years of follow-up. There have been no major CD complications or medication side effects.